A99 - not a 1/2 wave!!!
Ian.Sp...@ncl.ac.uk
The A99 is not a 1/2 wave antenna, contrary to the views which people
spout on this newgroup.
It is effectively a 3/4 wave antenna, although it is loaded. Anyone who
has seen the inside of the mid section will have seen that it is a widely
spaced coil. Hence the overall length of the radiating element is more
than 1/2 wavelength long.
People have been trying to claim that a MACO V5/8 must be better simply
because it is a 5/8 wave and the A99 is 'a 1/2 wave' antenna. Has anyone
directly compared the two? The radiation pattern of the A99 is superior
to the 5/8 anyway.
Thats all.
Ian
Michael Volz
That's really interesting. I always wondered what was up with the
rattling inside! :)
73,
Mike
Bill Eitner
Ian.Sp...@ncl.ac.uk wrote:
>
> The A99 is not a 1/2 wave antenna, contrary to the views which people
> spout on this newgroup.
> It is effectively a 3/4 wave antenna, although it is loaded. Anyone who
> has seen the inside of the mid section will have seen that it is a widely
> spaced coil. Hence the overall length of the radiating element is more
> than 1/2 wavelength long.
That makes no sense. The radiating element has to be a
certain fraction of a wavelength long to make the antenna
function properly. Besides, a 3/4 wavelength antenna has
no advantage over a 5/8 wave antenna. If it trully is
a tuned 3/4 wave, they wasted materials winding a coil
long enough to make a 1/2 wave antenna act like a 3/4
wave antenna. They, as well as you, wasted their time
and materials... Get over it!!
> People have been trying to claim that a MACO V5/8 must be better simply
> because it is a 5/8 wave and the A99 is 'a 1/2 wave' antenna. Has anyone
> directly compared the two? The radiation pattern of the A99 is superior
> to the 5/8 anyway.
> Thats all.
>
> Ian
You have to have an active amount of capture area to claim
wavelength superiority.
The A-99 is only 18 feet long. To claim superiority you need
to recognize an antenna that has a larger capture area. The
Maco V-58 does claim a larger capture area. A true 5/8 wave
antenna will be 21 to 22 feet long. The Maco V-58 is 21 feet
long.
I agree fully. To achieve a broader bandwidth, all the manufac-
turers will tune their antennas to the NEXT HIGHER 1/4 wave
increment. That means the coil size necessary to make a 1/2
wave antenna resonant will be bigger and wider spaced than that
necessary to resonate a true 5/8 wave antenna. Maybe that's
where your judgement failed.
The bottom line here is: any properly tuned 21 foot antenna will
outperform a properly tuned 18 foot antenna on the CB band. That's
because the 21 foot antenna has the characteristics of a 5/8 wave
antenna, while an 18 foot antennna has the characteristics of a
1/2 wave antenna.
Later.
--
-=[Bill Eitner]=-
Dogwodwind
I read the advertisment as a 3/4 over a 1/2 wave.
Ed Arnold
I have one. It's a quarter wave OVER half-wave... therefore is not truly
either a 3/4 wave nor a half-wave. Let Solorcon explain.
- Ed Arnold
Bill Eitner
Dogwodwind wrote:
>
> I read the advertisment as a 3/4 over a 1/2 wave.
If that were true, it would have to be at least 45 feet
long. A 3/4 wave section is roughly 27 feet long. Then
there would be a phasing section, and finally the 1/2
wave section at 18 feet long. If the phasing section took
up any space, the antenna would have to be even more than
45 feet long.
I think that, along with the original 9.9 db gain figure,
is nothing but marketing BS.
--
----------------------------------------
\ /
___ | ___
A
/ | \
-=[Bill Eitner]=- III
III
III
_________III_________
Ian.Sp...@ncl.ac.uk
Well then, can anyone explain why my A-99 (radiates like a 1/2 wave
supposedly) outperforms my 5/8 wave antenna (admittedly not a Maco v5/8)
quite easily. Both antennas at the same height, and the A-99 has
seriously better signal strength.
More gain, perhaps?
Ian
AL7KB
It is very possible there is a problem with your 5/8.
The difference between the performance of these two antennas should be
slight.
AL7KB
Also, there seems to be a lot of misunderstanding about antenna length.
I have even heard CB'ers say that to find out what "wave" your antenna
is you unwind the wire in the coil and add it to the length of the
antenna! Only the physical length of the antenna will determine its
configuration. The 5/8 wave vertical has the lowest angle of radiation
of them all (omnis). That is what the commercial broadcast stations try
to achieve.
Bruce Bennett
In article <5k1s00$a...@whitbeck.ncl.ac.uk> Ian.Sp...@ncl.ac.uk writes:
>From: Ian.Sp...@ncl.ac.uk
>Subject: Re: A99 - not a 1/2 wave!!!
>Date: 28 Apr 1997 09:52:00 GMT
>Well then, can anyone explain why my A-99 (radiates like a 1/2 wave
>supposedly) outperforms my 5/8 wave antenna (admittedly not a Maco v5/8)
>quite easily. Both antennas at the same height, and the A-99 has
>seriously better signal strength.
>More gain, perhaps?
>Ian
Well I had them both up side by side. The Maco was a bear to get thw SWR set
on. The A-99 came flat out of the box.
The A-99 outprreformed the V5/8 in both receive and transmit. The same station
approxamatly 10 miles away posted a 2 S unit difference on my transmitted
signal and I recognized a 1 to 2 S unit increase in recieved signal.
Not I didn't use a FSM or any other fancy form of measurement! I wanted the
people I talk to and my own ears to have been the judge. And they were.
I still don't understand the 1/2 wave over 1/4 wave myself, but I do understand
getting out better and better ears!
73's
Bill Eitner
AL7KB wrote:
>
> Ian.Sp...@ncl.ac.uk wrote:
> >
> > Well then, can anyone explain why my A-99 (radiates like a 1/2 wave
> > supposedly) outperforms my 5/8 wave antenna (admittedly not a Maco v5/8)
> > quite easily. Both antennas at the same height, and the A-99 has
> > seriously better signal strength.
> > More gain, perhaps?
> >
> > Ian
>
> The difference between the performance of these two antennas should be
> slight.
I agree. If anything, they should be about the same.
Either the 5/8 wave is bad, or it's in a dead spot.
You could try reversing their positions; or even playing
with the height a little each way can sometimes make
a noticable difference. Probably the best way to get a
conclusive answer would be to get a field strength meter
and actually measure the field strength. if the 5/8 wave
is working right, it will produce a slightly higher reading
at the lower angles of radiation and in all directions.
Let us know what you find.
philip de cadenet
In article <3361A3...@earthlink.net>, Bill Eitner
<kd6...@earthlink.net> writes
Or to put it another way, the 5/8 wave has a lower take off angle of
radiation than the 1/2 wave, same difference, nuff said !
Phil in the UK.
--
philip de cadenet
Steve Eklund
Ed Arnold <edar...@printplusdesign.com> writes: > I have one. It's a quarter wave OVER half-wave... therefore is not truly
> either a 3/4 wave nor a half-wave. Let Solorcon explain.
> - Ed Arnold
>
Sorry Ed. I took one apart and it is only a 1/2 wave antenna.
How could it be anything different if it is only 18 feet long?
I would love to hear them explain their way out of this one. It
must be a whopper of a story. Maybe they are caling their matching
section a 1/4 wave. Their matching section is certainly a little
different than those used by most 1/2 wave antennas, but it does
not change the fact that the A-99 is only an end-fed 1/2 wave.
73 from Steve
Steve Eklund
Bruce....@tek.com (Bruce Bennett) writes: > In article <5k1s00$a...@whitbeck.ncl.ac.uk> Ian.Sp...@ncl.ac.uk writes:
> >From: Ian.Sp...@ncl.ac.uk
> >Subject: Re: A99 - not a 1/2 wave!!!
> >Date: 28 Apr 1997 09:52:00 GMT
>
> >supposedly) outperforms my 5/8 wave antenna (admittedly not a Maco v5/8)
> >quite easily. Both antennas at the same height, and the A-99 has
> >seriously better signal strength.
> >More gain, perhaps?
>
> >Ian
>
> on. The A-99 came flat out of the box.
> The A-99 outprreformed the V5/8 in both receive and transmit. The same station
> approxamatly 10 miles away posted a 2 S unit difference on my transmitted
> signal and I recognized a 1 to 2 S unit increase in recieved signal.
>
> Not I didn't use a FSM or any other fancy form of measurement! I wanted the
> people I talk to and my own ears to have been the judge. And they were.
>
> I still don't understand the 1/2 wave over 1/4 wave myself, but I do understand
> getting out better and better ears!
>
> 73's
>
Funny! I noticed the opposite when I tested them, but the Maco antenna was generally only
a little bit better, maybe an average of 1/2 S-unit better.
You raise a couple of questions.
1. How were the antennas mounted and how close were they together?
2. What direction was the test station in relation to how the
antennas were mounted when you tested them?
Antennas can interact together and distort each other's unless
they are mounted far apart from each other. One antenna can
reenforce another antenna and cause more signal to be radiated
in a certain direction. The Maco may have acted as a reflector
for the A-99, which is why you saw such a difference. To be
fair, you must take the other antenna down and test them
using the same mast and coax, using many stations for reference points.
I guarantee that you will see varying amounts of difference between
the two. You mst take the average difference of many samplings
before you can draw any conclusions.
73 from Steve
Steve Eklund
Bruce....@tek.com (Bruce Bennett) writes: > In article <5k1s00$a...@whitbeck.ncl.ac.uk> Ian.Sp...@ncl.ac.uk writes:
> >From: Ian.Sp...@ncl.ac.uk
> >Subject: Re: A99 - not a 1/2 wave!!!
> >Date: 28 Apr 1997 09:52:00 GMT
>
> >Well then, can anyone explain why my A-99 (radiates like a 1/2 wave
> >supposedly) outperforms my 5/8 wave antenna (admittedly not a Maco v5/8)
> >quite easily. Both antennas at the same height, and the A-99 has
> >seriously better signal strength.
> >More gain, perhaps?
>
> >Ian
>
> Well I had them both up side by side. The Maco was a bear to get thw SWR set
> on. The A-99 came flat out of the box.
> The A-99 outprreformed the V5/8 in both receive and transmit. The same station
> approxamatly 10 miles away posted a 2 S unit difference on my transmitted
> signal and I recognized a 1 to 2 S unit increase in recieved signal.
>
> Not I didn't use a FSM or any other fancy form of measurement! I wanted the
> people I talk to and my own ears to have been the judge. And they were.
>
> I still don't understand the 1/2 wave over 1/4 wave myself, but I do understand
> getting out better and better ears!
>
> 73's
>
Funny! I notice the opposite, but the Maco Antenna was just a little
bit better, maybe 1/2 of an S-unit!
Steve
Steve Eklund
dogwo...@aol.com (Dogwodwind) writes: > I read the advertisment as a 3/4 over a 1/2 wave.
>
We all know how it is advertised, but it is not true.
They also claim 9.9 db gain in their ad, but what does that mean?
Their advertising claims are misleading and false. The A-99
is only a 1/2 wave antenna, which in theory only has 2.14 db gain
over an isotropic source!!! Take one apart and see for yourself!
There is nothing special about this antenna!
Steve
Steve Eklund
> >Ian.Sp...@ncl.ac.uk wrote:
> >>
> >> The A99 is not a 1/2 wave antenna, contrary to the views which people
> >> spout on this newgroup.
> >> It is effectively a 3/4 wave antenna, although it is loaded. Anyone who
> >> has seen the inside of the mid section will have seen that it is a widely
> >> spaced coil. Hence the overall length of the radiating element is more
> >> than 1/2 wavelength long.
> >
You obviously have never been one of those who HAS seen the
insides of an A-99 because if you had you will see that what you
are saying is wrong. The bottom two sections have nothing more
than number 12 bare copper wire inside. Believe me because I have
the insides of the bottom two sections of the A-99 sitting right
here in front of me as I type this. Come to think of it, now
that I look closer, the guage of the wire they use may only be
number 14. The top section is an 8 foot whip similar to a
mobile whip.
I don't know where you got your information, but it is hype,
it IS wrong, and you are one of the many victims of the CB hype
that is spread around about the A-99 and other CB antennas.
I said it before and I'll say it again, the A-99 is nothing
more than an end-fed 1/2 wave antenna that has two coils,
and a brass sleeve in its base, and two 'tuning rings' on
the outside. This makes up the matching circuit.
If anybody wants to view what is inside the base, you can see it at:
http://ourworld.compuserve.com/homepages/wa3rvt/a99.jpg
73 from Steve
Dino
In article <Bruce.Bennett...@tek.com>, Bruce....@tek.com
says...
>
>In article <5k1s00$a...@whitbeck.ncl.ac.uk> Ian.Sp...@ncl.ac.uk writes:
>>From: Ian.Sp...@ncl.ac.uk
>>Subject: Re: A99 - not a 1/2 wave!!!
>>Date: 28 Apr 1997 09:52:00 GMT
>
>>Well then, can anyone explain why my A-99 (radiates like a 1/2 wave
>>supposedly) outperforms my 5/8 wave antenna (admittedly not a Maco v5/8)
>>quite easily. Both antennas at the same height, and the A-99 has
>>seriously better signal strength.
>>More gain, perhaps?
>
>>Ian
>
>Well I had them both up side by side.
Is it possible that the A-99 INTERFERRED with the Maco? It could have
acted like a reflector. Many commercial antennas will use a mounted
reflector to create a null or to enhance the patter in a desired
direction. To eleiminate this, you need to mount one antenna at a
time on the SAME mount.
>The Maco was a bear to get the SWR set on.
Again, it is possible the antennas were interferring with eachother.
>The A-99 came flat out of the box. The A-99 outperformed the V5/8
>in both receive and transmit. The same station approximatly
>10 miles away posted a 2 S unit difference on my transmitted signal
>and I recognized a 1 to 2 S unit increase in recieved signal.
>
>No, I didn't use a FSM or any other fancy form of measurement!
>I wanted the people I talk to and my own ears to have been the
>judge. And they were.
>
>I still don't understand the 1/2 wave over 1/4 wave myself, but
>I do understand getting out better and better ears!
Actually, it is quite simple. Try to think of it in this way...
What you have is TWO antennas...a 1/2 wave antenna and a 1/4 wave
antenna. By mounting these antennas TOGETHER, you will have an
increased gain pattern. To physically mount these two antennas
together, you will need a PHASING HARNESS. Dual antennas on a
big-rig truck uses a PHASING HARNESS to connect BOTH antennas
on each mirror to the radio. The A-99 uses one to connect the
upper 1/2 wave radiator to the lower 1/4 wave radiator.
BUT, DON'T BE FOOLED!!!...The A-99 works but is by NO means an
efficient antenna. The gain is closer to 3.3DB. A 1/4 wave
antenna has ZERO gain and a 1/2 wave has approx 2.4 DBI. By
combining these antennas together, you effectively raise the gain
(but NOT to 9.9!)
One last question?....Are you using the same coax for the tests?
Dino...dinod@deltanet.com
>73's
WA8ULX
Bull a Quarter Wave is about 9Ft long a Half is about 18Ft for a Total of
about 27Ft I dont belive a A-99 is 27Feet, and as far as Gain what Gain it
Doesnt have any Gain
Mike Volz
AL7KB wrote:
>
> Bill Eitner wrote:
> >
> > Dogwodwind wrote:
> Only the physical length of the antenna will determine its
> configuration. The 5/8 wave vertical has the lowest angle of radiation
> of them all (omnis). That is what the commercial broadcast stations try
> to achieve.
No, the 3/4 wavelength and 7/8 wavelength antennas have lower angles of
radiation. If this were not so why does a 7/8 wavelength 'colinear'
antenna work so much better than a 5/8 wavelength? After using a 7/8
wave, I hated using a 5/8 wave! :)
73,
Mike
Dino
In article <3367EC...@avci.net>, mv...@avci.net says...
>No, the 3/4 wavelength and 7/8 wavelength antennas have lower angles of
>radiation. If this were not so why does a 7/8 wavelength 'colinear'
>antenna work so much better than a 5/8 wavelength? After using a 7/8
>wave, I hated using a 5/8 wave! :)
>
>73,
>Mike
There is a mis-conception here. A true 7/8 wave antenna would have a very
distorted radiation pattern. The MAXIMUM wave length that still maintains an
efficient pattern is the 5/8 wave antenna.
A 1/4 over a 1/2 is NOT a 3/4 wave antenna. A 5/8 over a 5/8 over a 1/4 is
not a 1.5 wave antenna. They ARE colinear antennas. Colinear antennas are
magic which when combine correctly (phased) offer an improved gain via
radiation pattern.
In theory the above statements are correct...a 3/4 and 7/8 wave antenna would
have a lower angle of radiation...they just don't work (very well).
Look at it this way, if they DID, don't you think the manufactures would make
and sell them?!
AL7KB
Dino is right-ask any broadcast engineer, they will tell you. The
antenna with the lowest angle of radiation and best ground wave signal
is a 5/8 wave. Anything shorter or longer will be worse.
AL7KB
Mike Volz wrote:
>
> AL7KB wrote:
> >
> > Bill Eitner wrote:
> > >
> > > Dogwodwind wrote:
> <snip>
> > Only the physical length of the antenna will determine its
> > configuration. The 5/8 wave vertical has the lowest angle of radiation
> > of them all (omnis). That is what the commercial broadcast stations try
> > to achieve.
>
> No, the 3/4 wavelength and 7/8 wavelength antennas have lower angles of
> radiation. If this were not so why does a 7/8 wavelength 'colinear'
> antenna work so much better than a 5/8 wavelength? After using a 7/8
> wave, I hated using a 5/8 wave! :)
>
> 73,
> Mike
What have you been smoking? A colinear is actually 2 or more antennas
with one feedline and matching harness. They are usually made of 1/2
wave antennas. A 7/8 would have a lousy, horrible pattern.
Bruce Bennett
In article <336851...@radio.com> AL7KB <h...@radio.com> writes:
>From: AL7KB <h...@radio.com>
>Subject: Re: A99 - not a 1/2 wave!!!
Sure you don't mean co-phased?
George Warner
> Dino wrote:
> >
> > In article <3367EC...@avci.net>, mv...@avci.net says...
> >
> > >No, the 3/4 wavelength and 7/8 wavelength antennas have lower angles of
> > >radiation. If this were not so why does a 7/8 wavelength 'colinear'
> > >antenna work so much better than a 5/8 wavelength? After using a 7/8
> > >wave, I hated using a 5/8 wave! :)
> > >
> > >73,
> > >Mike
> >
> > There is a mis-conception here. A true 7/8 wave antenna would have a very
> > distorted radiation pattern. The MAXIMUM wave length that still
maintains an
> > efficient pattern is the 5/8 wave antenna.
> >
> > A 1/4 over a 1/2 is NOT a 3/4 wave antenna. A 5/8 over a 5/8 over a 1/4 is
> > not a 1.5 wave antenna. They ARE colinear antennas. Colinear antennas are
> > magic which when combine correctly (phased) offer an improved gain via
> > radiation pattern.
> >
> > In theory the above statements are correct...a 3/4 and 7/8 wave
antenna would
> > have a lower angle of radiation...they just don't work (very well).
> >
> > Look at it this way, if they DID, don't you think the manufactures
would make
> > and sell them?!
> >
> > Dino...dinod@deltanet.com
>
>
> Dino is right-ask any broadcast engineer, they will tell you. The
> antenna with the lowest angle of radiation and best ground wave signal
> is a 5/8 wave. Anything shorter or longer will be worse.
This statement requires some qualifiers. 5/8 wave is the optimum
length for a grounded vertical antenna (6.03 dBd). (dBd is dB gain
relative to a dipole in free space). However, a 1/2 wave radiator
elevated 1/4 wavelength above the ground plane surpasses the 5/8 wave
antenna. For the elevated half-wave radiator, both the mutual
impedance between the radiator and its image, and the phases
between the direct and ground reflected waves are optimum, so that
they combine and provide a maximum gain (6.27 dBd).
George Warner
warn...@loveboat.com
Mike Volz
Bruce Bennett wrote:
>
> In article <336851...@radio.com> AL7KB <h...@radio.com> writes:
> >From: AL7KB <h...@radio.com>
> >Subject: Re: A99 - not a 1/2 wave!!!
> >Date: Thu, 01 May 1997 00:18:17 -0800
>
> >Mike Volz wrote:
> >>
> >> AL7KB wrote:
> >> >
> >> > Bill Eitner wrote:
> >> > >
> >> > > Dogwodwind wrote:
> >> <snip>
> >> > Only the physical length of the antenna will determine its
> >> > configuration. The 5/8 wave vertical has the lowest angle of radiation
> >> > of them all (omnis). That is what the commercial broadcast stations try
> >> > to achieve.
> >>
> >> radiation. If this were not so why does a 7/8 wavelength 'colinear'
> >> antenna work so much better than a 5/8 wavelength? After using a 7/8
> >> wave, I hated using a 5/8 wave! :)
> >>
> >> 73,
> >> Mike
> >with one feedline and matching harness. They are usually made of 1/2
> >wave antennas. A 7/8 would have a lousy, horrible pattern.
>
> Sure you don't mean co-phased?
No, the colinear simply has a coil in the middle to give correct phasing
and it sure gives a whallop over a 5/8 wave (on 2 meters). There are a
couple of different manufacturers of them (not for the CB band).
73,
Mike
Bill Eitner
George Warner wrote:
>
> In article <336851...@radio.com>, AL7KB <h...@radio.com> wrote:
>
> > Dino wrote:
> > >
> > > In article <3367EC...@avci.net>, mv...@avci.net says...
> > >
> > > >No, the 3/4 wavelength and 7/8 wavelength antennas have lower angles of
> > > >radiation. If this were not so why does a 7/8 wavelength 'colinear'
> > > >antenna work so much better than a 5/8 wavelength? After using a 7/8
> > > >wave, I hated using a 5/8 wave! :)
> > > >
> > > >73,
> > > >Mike
> > >
Some of that doesn't make sense to me. Can you site any
refereces so that I could study this further? What you
posted raises alot of questions.
George Warner
See "The handbook of Antenna Design" by A.W. Rudge, K. Milne,
A.D. Olver and P. Knight.
George Warner
warn...@loveboat.com
Ian.Sp...@ncl.ac.uk
Yes, I know how long a 1/4 wave and a 1/2 wave are. And I know the A-99
is only 18'. However if you'd bothered to look inside the A-99, you'd
discover that there is more than 18' of wire in there. I still say the
A-99 is a 3/4 wave antenna, albeit a loaded one. Never did I claim the
A-99 to be 27' long!
No gain? Yes, over another A-99 perhaps. However it most definitely has
gain (quite a lot) over a dipole, as I've tested it against various
antennas.
All I want to know is whether the Maco v5/8 is better for transmit than
the A-99 in terms of pure gain. Have Solarcon been telling us porkies
about the 9.9 dBi gain of the A-99? The Maco is stated as having 5 dBi.
People with A-99s say that their antenna is the best and the Maco is
inferior, and vice-versa.
Is someone going to give me an unbiased opinion?
Ian
HYPE
about antenas that it dosent matter how much wire is raped inside the
thing the size is what counts. The taller the antena the bigger
rateating area thair for a better antena. I have a cousen who has a A99
and has had good results with it but he still beleves that the bigger
the antena the better it will get out and receve. I may be rong but I
don't think so. Also dose anybody now ware I could get a 7/8 wav or even
a full wave linth antena?
LATER,
HYPE
Bruce Bennett
In article <5kccbk$a...@whitbeck.ncl.ac.uk> Ian.Sp...@ncl.ac.uk writes:
>From: Ian.Sp...@ncl.ac.uk
>Subject: Re: A99 - not a 1/2 wave!!!
>wa8...@aol.com (WA8ULX) wrote:
>>
>>Bull a Quarter Wave is about 9Ft long a Half is about 18Ft for a Total of
>>about 27Ft I dont belive a A-99 is 27Feet, and as far as Gain what Gain it
>>Doesnt have any Gain
>Yes, I know how long a 1/4 wave and a 1/2 wave are. And I know the A-99
>is only 18'. However if you'd bothered to look inside the A-99, you'd
>discover that there is more than 18' of wire in there. I still say the
>A-99 is a 3/4 wave antenna, albeit a loaded one. Never did I claim the
>A-99 to be 27' long!
>No gain? Yes, over another A-99 perhaps. However it most definitely has
>gain (quite a lot) over a dipole, as I've tested it against various
>antennas.
>All I want to know is whether the Maco v5/8 is better for transmit than
>the A-99 in terms of pure gain. Have Solarcon been telling us porkies
>about the 9.9 dBi gain of the A-99? The Maco is stated as having 5 dBi.
>People with A-99s say that their antenna is the best and the Maco is
>inferior, and vice-versa.
>Is someone going to give me an unbiased opinion?
>Ian
I thought I did several days ago with my A/B comparision.
Bruce
AL7KB
The length of wire inside an antenna has NOTHING TO DO WITH THE
WAVELENGTH. It is the overall length. This is about the same as
unwinding a coil and measuring the lengthof it, and adding it to the
length of the antenna. I have actually heard some CB'ers say that thats
the way to measure the wavelength of antennas, by unwinding coils and
measuring. NOT!
Robert B. Zimmerman
AL7KB wrote:
>
> The length of wire inside an antenna has NOTHING TO DO WITH THE
> WAVELENGTH. It is the overall length. This is about the same as
> unwinding a coil and measuring the lengthof it, and adding it to the
> length of the antenna. I have actually heard some CB'ers say that thats
> the way to measure the wavelength of antennas, by unwinding coils and
> measuring. NOT!
Then why are the coils there? It is not Physical length of the antenna
then counts. It the length including coils etc. There for you can put a
1/4 wave in an antenna only 36" long. This does not mean it will perform
as well as the full length 1/4.
--
Bob Zimmerman - KC8CLB Diversity: The longer you verk here,
E-Mail: bo...@umich.edu deverse it gets.
unit77
WA8ULX
Again another person that has no Idea what an Antenna is.
AL7KB
Right--the coil adds inductive reactance to the antenna, allowing you to
use a shorter antenna than without the coil. The length of wire in the
coil is irrelevant,(in regards to the wavelength of the antenna) and the
reactance (inductive) of the coil depends on several things-diameter of
the coil, spacing between coils, size of the wire.
Ed Arnold
> Sorry Ed. I took one apart and it is only a 1/2 wave antenna.
> How could it be anything different if it is only 18 feet long?
> I would love to hear them explain their way out of this one. It
> must be a whopper of a story. Maybe they are caling their matching
> section a 1/4 wave. Their matching section is certainly a little
> different than those used by most 1/2 wave antennas, but it does
> not change the fact that the A-99 is only an end-fed 1/2 wave.
>
Guess you'll have to ask Solorcon why they call it 1/4 wave over 1/2
wave. However, from my experience, it is not so uncommon to devise an
antenna that is a certain measurement in height but is electrically
longer.
Ed
Ian.Sp...@ncl.ac.uk
unit77 <n...@yadamned.business> wrote:
>Robert B. Zimmerman wrote:
>>
>> AL7KB wrote:
>>
>> >
>> > The length of wire inside an antenna has NOTHING TO DO WITH THE
>> > WAVELENGTH. It is the overall length. This is about the same as
>> > unwinding a coil and measuring the lengthof it, and adding it to the
>> > length of the antenna. I have actually heard some CB'ers say that thats
>> > the way to measure the wavelength of antennas, by unwinding coils and
>> > measuring. NOT!
>>
>> Then why are the coils there? It is not Physical length of the antenna
>> then counts. It the length including coils etc. There for you can put a
>> 1/4 wave in an antenna only 36" long. This does not mean it will perform
>> as well as the full length 1/4.
>>
>> --
>>
>> Bob Zimmerman - KC8CLB Diversity: The longer you verk here,
>> E-Mail: bo...@umich.edu deverse it gets.
> Coils are used to provide inductive reactance.
What I am talking about is a LOADED antenna, not just a bit of straight
wire with a tuning coil at the bottom. Yes, there is a tuning coil at the
bottom of the A-99 but what I am saying is the majority of the antenna is
loaded, ie it is in a kind of loose coil, like a lot of mobile antennas.
The top section is a 6' piece of wire, not 8' as someone wrote who
claimed to have tried the A99 and found it to be inferior.
Enough of this 'is the A99 a 1/2 wave?', 'does the A99 have 9.9dBi?'
stuff, what I really want to know is whether or not the A99 is better
than the Maco v5/8 or not for transmit. There has been a lot of talk
about antennas only radiating in accordance with their overall length, ie
the A99 radiating like a 1/2 wave. If this is true, then is not the Maco
v5/8 actually a 1/2 wave antenna? It is quoted by Copper Electronics as
being of length 16.5 - 20'. How can this be a 5/8 wave then? it sounds
like the Maco is just a 1/2 wave antenna with a tuning coil at the
bottom, probably 1/8 wavelength long. So if this is the case, will the
gain of the Maco not be the same as the A99? If so, I definitely won't
change to a Maco because aluminum aerials don't seem to last too long.
Steve Eklund
Enough of this 'is the A99 a 1/2 wave?', 'does the A99 have 9.9dBi?'
> stuff, what I really want to know is whether or not the A99 is better
> than the Maco v5/8 or not for transmit. There has been a lot of talk
> about antennas only radiating in accordance with their overall length, ie
> the A99 radiating like a 1/2 wave. If this is true, then is not the Maco
> v5/8 actually a 1/2 wave antenna? It is quoted by Copper Electronics as
> being of length 16.5 - 20'. How can this be a 5/8 wave then? it sounds
> like the Maco is just a 1/2 wave antenna with a tuning coil at the
> bottom, probably 1/8 wavelength long. So if this is the case, will the
> gain of the Maco not be the same as the A99? If so, I definitely won't
> change to a Maco because aluminum aerials don't seem to last too long.
>
>
>
Aluminum antennas don't last as long? Tell that to the owners of
Super Penetrators, Stardusters, Ringos, Astroplanes, Super Mags,
Sigmas and others. Many of them are still going strong after
20 plus years.
Fiberglass antennas, on the other hand, tend to flake off their paint
after only a few years. Some will even begin to absorb water.
Some start to splinter and some just snap in two after the joints
weaken. Anybody out there still using a fiberglass CB antenna that
is over 20 years old? Even most commercial fiberglass repeater
antennas have to be replaced before then!
73 from Steve
MR.Bob
Steve Eklund <wa3...@compuserve.com> wrote in article
<567cd$d1325.65@NEWS>...
> Enough of this 'is the A99 a 1/2 wave?', 'does the A99 have 9.9dBi?'
> > stuff, what I really want to know is whether or not the A99 is better
> > than the Maco v5/8 or not for transmit.
.....Neither antenna is better than the other in terms of gain.
.....The theoretical difference is slight.
.....If you want a A99 to perform like a Maco 5/8 then put a radial kit
under it.Voila, you have a Maco 5/8.
.....The gain of each antenna is the same but at what elevation is the main
lobe of power being sent?
.....The real reason regarding the difference in performance between the
two is that one has radials and the other doesn't.
..... By adding radials you will lower the angle of radiation and present
the locals with more radio energy than before.
.....I cant recall what the actual length of the Maco is. I think it is
about 17 or 18 feet roughly.If this were a true 5/8 wave antenna it would
be about 4 feet longer.
....Even if it were 4 feet longer the gain would still be about the same.
.....The 5/8 wave antenna came along as an easier way to match the antenna
to the coax. It uses the extra 4 feet as a sort of impedance transformer to
bring the high impedance of the 1/2 wave antenna down so the coil doesn't
have to do all the work of transforming the impedances.This enables them to
use a coil of less turns and larger diameter wire to handle power and keep
coil losses lower.
.....As far as longevity is concerned. If you treat the fiberglass with a
coating of anything that will keep the ultraviolet rays from eating it up
the antenna will last easily as long as any metal one.Even a coat of
car/boat wax will suffice. It's just fiberglass.
.....The same holds true for metal antennas. You need to coat them with
something even if it's just where the sections meet. This is where the
metal antennas loose connection due to corrossion. This will cause a slight
rise in SWR but at the same time will cause harmonics by rectification. You
think you bother some stuff now? Wait till you see who you bother with an
antenna that is generating harmonics and noise well up into the uhf
spectrum. And it doesn't take long for this to happen. About 6mo. to a year
in a humid climate without protection.
..... I hope this has helped. Any questions or comments will be read with
interest and answered as soon as possible.
Andy Moss
MR.Bob wrote:
> ..... By adding radials you will lower the angle of radiation and present
> the locals with more radio energy than before.
I would agree (generally) with this remark.
> .....I cant recall what the actual length of the Maco is. I think it is
> about 17 or 18 feet roughly.If this were a true 5/8 wave antenna it would
> be about 4 feet longer.
> ....Even if it were 4 feet longer the gain would still be about the same.
> .....The 5/8 wave antenna came along as an easier way to match the antenna
> to the coax. It uses the extra 4 feet as a sort of impedance transformer to
> bring the high impedance of the 1/2 wave antenna down so the coil doesn't
> have to do all the work of transforming the impedances.This enables them to
> use a coil of less turns and larger diameter wire to handle power and keep
> coil losses lower.
I'm no antenna expert but I don't think this is quite correct. The 5/8
antenna has the advantage over a 1/2 wave in that it has a lower
radiation angle. It's actually half of a Zep antenna. The feedpoint
impedance of a 1/2 wave is very high and a coil (or capacitor) must be
used to match the impedance. You'll find that most 5/8 antennas (but
not all) are "shunt" fed. There are two reasons for this. One is to
provide a near perfect 50 Ohm feedpoint (to match your coax) and the
other is to provide a DC ground to the radiating element to suppress
static.
> .....As far as longevity is concerned. If you treat the fiberglass with a
> coating of anything that will keep the ultraviolet rays from eating it up
> the antenna will last easily as long as any metal one.Even a coat of
> car/boat wax will suffice. It's just fiberglass.
There are different grades of fiberglass and many are porous. It is my
suspcion that the fiberglass used to make a 50$ antenna CB is somewhat
less than excellent. Aluminum is aluminum. My 5/8ths is 20+ years old
and it's made of metal. All the "Big Sticks" of that vintage are
splintered garbage now.
> .....The same holds true for metal antennas. You need to coat them with
> something even if it's just where the sections meet. This is where the
> metal antennas loose connection due to corrossion. This will cause a slight
> rise in SWR but at the same time will cause harmonics by rectification.
Agreed. Compression fittings on metal antennas are about 100 times
better than the bolt-through-hole type. These eliminate the problems of
electrolysis and flex.
You
> think you bother some stuff now? Wait till you see who you bother with an
> antenna that is generating harmonics and noise well up into the uhf
> spectrum. And it doesn't take long for this to happen. About 6mo. to a year
> in a humid climate without protection.
In my experience, you get more problems with RFI saturation than
harmonic generation. I guess if your next door neighbor is not on cable
and watches channel 2 or 3 in the fringe are you might get a problem.
> ..... I hope this has helped. Any questions or comments will be read with
> interest and answered as soon as possible.
Always!
Cheers!
--
Andy Moss
"In God we trust - the rest can pay cash......."
Bruce Bennett
In article <567cd$d1325.65@NEWS> Steve Eklund <wa3...@compuserve.com> writes:
>From: Steve Eklund <wa3...@compuserve.com>
>Subject: Re: A99 - not a 1/2 wave!!!
>Enough of this 'is the A99 a 1/2 wave?', 'does the A99 have 9.9dBi?'
>> stuff, what I really want to know is whether or not the A99 is better
>> than the Maco v5/8 or not for transmit. There has been a lot of talk
>> about antennas only radiating in accordance with their overall length, ie
>> the A99 radiating like a 1/2 wave. If this is true, then is not the Maco
>> v5/8 actually a 1/2 wave antenna? It is quoted by Copper Electronics as
>> being of length 16.5 - 20'. How can this be a 5/8 wave then? it sounds
>> like the Maco is just a 1/2 wave antenna with a tuning coil at the
>> bottom, probably 1/8 wavelength long. So if this is the case, will the
>> gain of the Maco not be the same as the A99? If so, I definitely won't
>> change to a Maco because aluminum aerials don't seem to last too long.
>>
>>
>>
Snip
See my review of A/B comparison of Maco and Solarcon.
Check Deja-News for the start of this thread.
73's,
Bruce
AL7KB
MR.Bob wrote:
>
> MR.Bob <cas...@gte.net> wrote in article
> <01bc5a83$5d568c60$a8e973cf@radio-bob>...
> >
> >
> > MR.Bob <cas...@gte.net> wrote in article
> > <01bc5a6b$7461d3a0$16e973cf@radio-bob>...
> > > > > stuff, what I really want to know is whether or not the A99 is
> better
> >
> > > > > than the Maco v5/8 or not for transmit.
> > > ......The theoretical difference is slight.
> > > ......If you want a A99 to perform like a Maco 5/8 then put a radial
> kit
> > > under it.Voila, you have a Maco 5/8.
> > main
> > > lobe of power being sent?
> > the
> > > two is that one has radials and the other doesn't.
> > present
> > > the locals with more radio energy than before.
> is
> > > about 17 or 18 feet roughly.If this were a true 5/8 wave antenna it
> would
> > > be about 4 feet longer.
> > same.
> > > ......The 5/8 wave antenna came along as an easier way to match the
> > antenna
> > > to the coax. It uses the extra 4 feet as a sort of impedance
> transformer
> > to
> > > bring the high impedance of the 1/2 wave antenna down so the coil
> doesn't
> > > have to do all the work of transforming the impedances.This enables
> them
> > to
> > > use a coil of less turns and larger diameter wire to handle power and
> > keep
> > > coil losses lower.
> with
> > a
> > > coating of anything that will keep the ultraviolet rays from eating it
> up
> > > the antenna will last easily as long as any metal one.Even a coat of
> > > car/boat wax will suffice. It's just fiberglass.
> with
> > > something even if it's just where the sections meet. This is where the
> > > metal antennas loose connection due to corrossion. This will cause a
> > slight
> > > rise in SWR but at the same time will cause harmonics by rectification.
> > > think you bother some stuff now? Wait till you see who you bother with
> an
> > > antenna that is generating harmonics and noise well up into the uhf
> > > spectrum. And it doesn't take long for this to happen. About 6mo. to a
> > year
> > > in a humid climate without protection.
> > with
> > > interest and answered as soon as possible.
> > >
> > >
> > >
> > > > Super Penetrators, Stardusters, Ringos, Astroplanes, Super Mags,
> > > > Sigmas and others. Many of them are still going strong after
> > > > 20 plus years.
> > > >
> > > > Fiberglass antennas, on the other hand, tend to flake off their paint
> > > > after only a few years. Some will even begin to absorb water.
> > > > Some start to splinter and some just snap in two after the joints
> > > > weaken. Anybody out there still using a fiberglass CB antenna that
> > > > is over 20 years old? Even most commercial fiberglass repeater
> > > > antennas have to be replaced before then!
> > > >
> > > > 73 from Steve
> > > >
> > > >
> > > >
Jeez already. Will the thread ever end? There is a major difference
between an end fed 1/2 wave antenna and a 5/8 groundplane. Much more
than one having radials and one not having them. The 5/8 vertical must
have a groundplane under it to perform properly. The coil used at the
base is for impedance transformation to around 50 ohms. It will achieve
the lowest angle of radiation of all verticals, properly installed. The
A99 is a 1/2 wave end fed dipole, pure and simple. It requires no
groundplane, since the antenna itself is a 1/2 wave, which does not need
a groundplane. All other things being equal, a 5/8 groundplane will
have a lower angle of radiation than a 1/2 wave, (A99 or any other
similar). I have not seen a Maco 58, but there are several reasons I
can think of that could cause the overall length at resonance in the CB
band to be less than the theoretical length derived from the classic
formula. Does the Maco utilize a tophat? I don't know. Capacity hats
will reduce the length required of an antenna by an amount roughly equal
to twice the diameter of the hat. For example, a 1 foot hat would
reduce the length of the antenna by about 2 feet. Also, a vertical does
not have to be a full 5/8 wavelength long to outperform a 1/2 wave
dipole for low angle radiation. It can be somewhat shorter than this,
and the feedpoint impedance can be matched with a coil at the base.
MR.Bob
MR.Bob
MR.Bob
Joe Bennett GJ0NYG
This does look fun....
Right, a vertical antenna is as efficient as it's RADIATING length with
respect to the
current flowing along it. A 17 foot long CB antenna is a half-wave,
impedance at the base
several Kohms, requiring a matching xformer to connect to 50 ohm co-ax.
A 21 foot CB
antenna is a 5/8 wave with an impedance xformer at the base. Due to the
length of the 5/8
it does have a slightly higher theoretical gain BUT........
it needs a perfect ground extending for many wavelenths underneath it.
This gives it the
extendeded zepp effect by using the earth mirror image. This raises the
angle of takeoff,
which is not good for local working. A halfwave however does not need a
ground plane. In fact
adding one raises the takeoff angle.... NOT good for local working.
So....
A 5/8 needs a perfect ground, so really should be mounted at ground
level
A half wave monopole( end fed vert) needs no ground plane so can be
raised higher, so giving
a greater line of site range.
A 5/8 has a small gain of approx 2dB over a dipole but at a HIGHER angle
A halfwave dipole has a gain of 0dB over a dipole and 2.1 dBi. Adding a
ground plane screws
things up.
Can I say this enough times? YOU DON'T WANT A GROUND PLANE.
Buy a nice halfwave (fibre or alum, I don't care) and stick it up AS
HIGH AS POSSIBLE.
Steve Eklund
"MR.Bob" <cas...@gte.net> writes: >
>
>
> .....Neither antenna is better than the other in terms of gain.
This is wrong. A 5/8 wave antenna has a 1 db gain advantage over a 1/2 wave antenna.
> .....The theoretical difference is slight.
1 db is 1 db, although I would agree that the difference is small.
> .....If you want a A99 to perform like a Maco 5/8 then put a radial kit
> under it.Voila, you have a Maco 5/8.
Wrong. Radials are used to decouple RF from the coax, mast and
mounting brackets. They are only needed if there is a significant
amount of RF there. There will be high amounts of antenna
current present at the base only if the base impedance of the
antenna is low. If the base impedance is high, the antenna current
will be low. A 1/2 wave antenna has about a 1000 ohm feedpoint.
A 5/8 wave antenna's feedpoint is much, much lower. I think
it is about 20 ohms, but I don't remember for sure. Radials are
necessary on a 5/8 wave but not necessary on a 1/2 wave.
> .....The gain of each antenna is the same but at what elevation is the main
> lobe of power being sent?
I don't remember the exact number of degrees above the horizon
that the main lobe of each antenna is best, but I do know for sure
that the main lobe of the 5/8 wave is more 'pancaked' and closer
to the horizon than the 1/2 wave. The 1/2 wave's pattern looks
like a figure 8 turned on its side, with the lobes tilted upward
a bit. The 5/8 wave is similar, but the circles are more elliptical,
and closer to the horizon.
> .....The real reason regarding the difference in performance between the
> two is that one has radials and the other doesn't.
Again, as explained above, this is not true.
> ..... By adding radials you will lower the angle of radiation and present
> the locals with more radio energy than before.
Even with the main lobe having a higher angle of radiation,
this lobe is very fat and rounded. More energy is wasted going
up and down than a 5/8 wave. The lobes of the 5/8 wave are
more 'squashed' at the top and bottom, resulting in more
energy saved for the highest radiation point, and less going into
your neighbor's houses.
> .....I cant recall what the actual length of the Maco is. I think it is
> about 17 or 18 feet roughly.If this were a true 5/8 wave antenna it would
> be about 4 feet longer.
They reccommend 240 inches for 27 Mhz. That is 20 feet. Most users
have found that the antenna needs to be shortened to between 229 and
235 inches to achieve a perfect match. Even the shortest figure
is 19.08 feet. While that is a little short to be a true 5/8
wave, it is too long to be a 1/2 wave antenna. The Maco antenna
behaves like a 5/8 wave, even if it is a little short physically.
> ....Even if it were 4 feet longer the gain would still be about the same.
> .....The 5/8 wave antenna came along as an easier way to match the antenna
> to the coax. It uses the extra 4 feet as a sort of impedance transformer to
> bring the high impedance of the 1/2 wave antenna down so the coil doesn't
> have to do all the work of transforming the impedances.This enables them to
> use a coil of less turns and larger diameter wire to handle power and keep
> coil losses lower.
The figure is between 2 1/2 and 3 feet longer for the Maco, but
the extra length is not used as an impedance transformer. A 5/8 wave
antenna behaves different from a 1/2 wave even though its impedance
is lower. I will agree, however, that it is easier to match a
5/8 wave antenna to a 52 ohm impedance than it is to match
a 1/2 wave, but the antennas exhibit different radiation patterns.
> .....As far as longevity is concerned. If you treat the fiberglass with a
> coating of anything that will keep the ultraviolet rays from eating it up
> the antenna will last easily as long as any metal one.Even a coat of
> car/boat wax will suffice. It's just fiberglass.
I reccommend treating a fiberglass antenna every 2 to 3 years to keep the paint
from flaking off. Re-painting it is best, but more trouble.
> .....The same holds true for metal antennas. You need to coat them with
> something even if it's just where the sections meet. This is where the
> metal antennas loose connection due to corrossion. This will cause a slight
> rise in SWR but at the same time will cause harmonics by rectification. You
> think you bother some stuff now? Wait till you see who you bother with an
> antenna that is generating harmonics and noise well up into the uhf
> spectrum. And it doesn't take long for this to happen. About 6mo. to a year
> in a humid climate without protection.
> ..... I hope this has helped. Any questions or comments will be read with
> interest and answered as soon as possible.
>
What you say is true about the joints, but the Maco Alpha v 5/8
uses specially designed clamps instead of screws to keep the
sections tightly bound together. Some other aluminum antennas use
screws which weaken and distort the holes over a period of time
due to the back and forth motion of the antenna. You could use
some sort of 'no-ox' compound where the sections telescope
together, but I don't think you will have much trouble with this
antenna. A good idea would be to treat the antenna with vinegar
before you assemble it. This will cut down on the 'white'powder'
oxidization that is common with aluminum antennas, but will discolor
the antenna a bit. It will look dull and not shiney, but over a period
of time all aluminum antennas loose their shine anyway. Besides,
who cares as long as it works right?
73 from Steve
RadioNut
If it is in fact a 3/4 wave, that really sucks, because a 3/4 wave antenna
has less signal strength at the horizon than a 1/4 wave!
The 21' long antenna is a wise knowledgeable choice!
AL7KB
Andy Moss wrote:
>
> MR.Bob wrote:
>
> > ..... By adding radials you will lower the angle of radiation and present
> > the locals with more radio energy than before.
>
>
> > about 17 or 18 feet roughly.If this were a true 5/8 wave antenna it would
> > be about 4 feet longer.
would indicate solely because it utilizes a capacity hat. This shortens
the length of the vertical element of the antenna by an amount roughly
equal to twice the diameter of the capacity hat. The hat adds
capacitive reactance to the antenna, reducing the length needed for the
antenna. It is a true 5/8 wave antenna.
> > ....Even if it were 4 feet longer the gain would still be about the same.
> > .....The 5/8 wave antenna came along as an easier way to match the antenna
> > to the coax. It uses the extra 4 feet as a sort of impedance transformer to
> > bring the high impedance of the 1/2 wave antenna down so the coil doesn't
> > have to do all the work of transforming the impedances.
impedance of the antenna enough to measure. All 5/8 wave antennas
require a matching network to transform the feedpoint impedance to close
to 50 ohms. The "missing 4 feet" does not matter.
This enables them to
> > use a coil of less turns and larger diameter wire to handle power and keep
> > coil losses lower.
dissipates very little power in the circuit, it is not an active element
of the antenna, like a loading coil is. It is strictly for matching
impedances of feedline and antenna.
>
> I'm no antenna expert but I don't think this is quite correct. The 5/8
> antenna has the advantage over a 1/2 wave in that it has a lower
> radiation angle. It's actually half of a Zep antenna. The feedpoint
> impedance of a 1/2 wave is very high and a coil (or capacitor) must be
> used to match the impedance. You'll find that most 5/8 antennas (but
> not all) are "shunt" fed. There are two reasons for this. One is to
> provide a near perfect 50 Ohm feedpoint (to match your coax) and the
> other is to provide a DC ground to the radiating element to suppress
> static.
>
> > coating of anything that will keep the ultraviolet rays from eating it up
> > the antenna will last easily as long as any metal one.Even a coat of
> > car/boat wax will suffice. It's just fiberglass.
>
> suspcion that the fiberglass used to make a 50$ antenna CB is somewhat
> less than excellent. Aluminum is aluminum. My 5/8ths is 20+ years old
> and it's made of metal. All the "Big Sticks" of that vintage are
> splintered garbage now.
>
> > something even if it's just where the sections meet. This is where the
> > metal antennas loose connection due to corrossion. This will cause a slight
> > rise in SWR but at the same time will cause harmonics by rectification.
>
> better than the bolt-through-hole type. These eliminate the problems of
> electrolysis and flex.
>
> > think you bother some stuff now? Wait till you see who you bother with an
> > antenna that is generating harmonics and noise well up into the uhf
> > spectrum. And it doesn't take long for this to happen. About 6mo. to a year
> > in a humid climate without protection.
>
> harmonic generation. I guess if your next door neighbor is not on cable
> and watches channel 2 or 3 in the fringe are you might get a problem.
>
> > interest and answered as soon as possible.
>
Mike Volz
> I am looking into one of theis Maco V 5/8 myself. From what I understand
> about antenas that it dosent matter how much wire is raped inside the
> thing the size is what counts. The taller the antena the bigger
> rateating area thair for a better antena. I have a cousen who has a A99
> and has had good results with it but he still beleves that the bigger
> the antena the better it will get out and receve. I may be rong but I
> don't think so. Also dose anybody now ware I could get a 7/8 wav or even
> a full wave linth antena?
> LATER,
> HYPE
You have it right. Length is what counts. There used to be a
company(s) making 3/4 wavelength verticals. However, they were very
long and tended to break off in high winds and ice. The last one I knew
of in use broke off this winter.
73,
Mike
Mike Volz
Joe Bennett GJ0NYG wrote:
>
>
<snip>
> A 5/8 needs a perfect ground, so really should be mounted at ground
> level
> A half wave monopole( end fed vert) needs no ground plane so can be
> raised higher, so giving
> a greater line of site range.
> A 5/8 has a small gain of approx 2dB over a dipole but at a HIGHER angle
> A halfwave dipole has a gain of 0dB over a dipole and 2.1 dBi. Adding a
> ground plane screws
> things up.
> Can I say this enough times? YOU DON'T WANT A GROUND PLANE.
> Buy a nice halfwave (fibre or alum, I don't care) and stick it up AS
> HIGH AS POSSIBLE.
If you don't want a groundplane, why do you want the antenna at the
ground?
A groundplane lowers the radiation angle, giving the antenna gain over
one without a groundplane. The better the groundplane, the more gain
you get. However, there is a practical limit, but the more you have the
better. Why do commerical broadcast staions on the 180 meter band put
down hundreds of ground wires spread out??
73,
Mike
AL7KB
Mike Volz wrote:
>
> Joe Bennett GJ0NYG wrote:
> >
> >
> <snip>
> > A 5/8 needs a perfect ground, so really should be mounted at ground
> > level
A 5/8 vertical as sold commonly for the CB band has a groundplane on it,
you would be crazy to mount on the ground. It can be mounted at any
height.
> > A half wave monopole( end fed vert) needs no ground plane so can be
> > raised higher, so giving
> > a greater line of site range.
> > A 5/8 has a small gain of approx 2dB over a dipole but at a HIGHER angle
This is completely false. The 5/8 vertical has the lowest angle of
radiation of all vertical antennas, including any 1/2 wave, when
comparing at the same height above ground.
> > A halfwave dipole has a gain of 0dB over a dipole and 2.1 dBi. Adding a
> > ground plane screws
> > things up.
> > Can I say this enough times? YOU DON'T WANT A GROUND PLANE.
> > Buy a nice halfwave (fibre or alum, I don't care) and stick it up AS
> > HIGH AS POSSIBLE.
>
> If you don't want a groundplane, why do you want the antenna at the
> ground?
>
> A groundplane lowers the radiation angle, giving the antenna gain over
> one without a groundplane. The better the groundplane, the more gain
> you get.
Not exactly. The groundplane provided with a 5/8 CB antenna is more
than adequate, you do not need hundreds of radials for peak
performance. The reason commercial broadcast stations use all those
radials is because they are ground mounted. If they could elevate a
broadcast vertical high enough above ground (which is not possible) you
would only need about 4 radials to do the same job as 120 radials when
mounted on the ground.
However, there is a practical limit, but the more you have the
> better. Why do commerical broadcast staions on the 180 meter band put
> down hundreds of ground wires spread out??
Anything over 120 ground radials 1/2 wavelength long is a waste on a
broadcast antenna. That is the standard-120 1/2 wavelength radials.
>
> 73,
> Mike
sa...@techline.com
AL7KB <H...@radio.com> wrote:
>Mike Volz wrote:
Bought an A99 with the GPK-1 and it has always worked GREAT!!! No
problems, in fact, it took care of the problems that I started having
with bleeding on my parents' TV. and the neighbor's telephones.
Josh
George Warner
> Andy Moss wrote:
> >
> > MR.Bob wrote:
> >
> > > ..... By adding radials you will lower the angle of radiation and present
> > > the locals with more radio energy than before.
> >
> > I would agree (generally) with this remark.
> >
> > > .....I cant recall what the actual length of the Maco is. I think it is
> > > about 17 or 18 feet roughly.If this were a true 5/8 wave antenna it would
> > > be about 4 feet longer.
> Not true, the Maco 5/8 is shorter than the classic formula for a 5/8
> would indicate solely because it utilizes a capacity hat. This shortens
> the length of the vertical element of the antenna by an amount roughly
> equal to twice the diameter of the capacity hat. The hat adds
> capacitive reactance to the antenna, reducing the length needed for the
> antenna. It is a true 5/8 wave antenna.
What are you talking about when you say "capacity hat?" The Maco 5/8
has no "capacity hat." It has nothing at the top; it does have a matching
ring at the base.
My Maco 5/8 is 19.08' feet (229") long and I'm still trying to figure
out how they call it 5/8 wave antenna. This calculates to 0.53 wavelengths.
Coincidentally, I was just looking in the 1989 ARRL handbook. They
had a 5/8 wave 220 MHz antenna. That antenna is 28.5" long. My
calculations show this to be 0.53 wavelengths.
Why are all these "5/8 wave" antennas 0.53 wavelengths long?
> > I'm no antenna expert but I don't think this is quite correct. The 5/8
> > antenna has the advantage over a 1/2 wave in that it has a lower
> > radiation angle. It's actually half of a Zep antenna. The feedpoint
> > impedance of a 1/2 wave is very high and a coil (or capacitor) must be
> > used to match the impedance. You'll find that most 5/8 antennas (but
> > not all) are "shunt" fed. There are two reasons for this. One is to
> > provide a near perfect 50 Ohm feedpoint (to match your coax) and the
> > other is to provide a DC ground to the radiating element to suppress
> > static.
I wouldn't call it a Zepp antenna. I'd call it a vertical ground plane.
It is still debatable whether it is a 5/8 wave or 1/2 wave vertical
ground plane.
George Warner
warn...@loveboat.com
AL7KB
Andy Moss wrote:
>
> AL7KB wrote:
>
> > A half wave monopole( end fed vert) needs no ground plane so can be
> > raised higher, so giving
> > a greater line of site range.
> > A 5/8 has a small gain of approx 2dB over a dipole but at a HIGHER angle
>
> > This is completely false. The 5/8 vertical has the lowest angle of
> > radiation of all vertical antennas, including any 1/2 wave, when
> > comparing at the same height above ground.
>
> radiation angle. That's why "Super Scanners" *tend* to do better with
> long hop type skip.
>
> > > A groundplane lowers the radiation angle, giving the antenna gain over
> > > one without a groundplane. The better the groundplane, the more gain
> > > you get.
>
> > Not exactly. The groundplane provided with a 5/8 CB antenna is more
> > than adequate, you do not need hundreds of radials for peak
> > performance. The reason commercial broadcast stations use all those
> > radials is because they are ground mounted. If they could elevate a
> > broadcast vertical high enough above ground (which is not possible) you
> > would only need about 4 radials to do the same job as 120 radials when
> > mounted on the ground.
>
> really would like to know.
>
> > However, there is a practical limit, but the more you have the
> > > better. Why do commerical broadcast staions on the 180 meter band put
> > > down hundreds of ground wires spread out??
>
> > Anything over 120 ground radials 1/2 wavelength long is a waste on a
> > broadcast antenna. That is the standard-120 1/2 wavelength radials.
>
> I do know that VLF Beacons use lots of ground radials but I'm not
> convinced they are necessary.
>
> Cheers
> --
> Andy Moss
> "In God we trust - the rest can pay cash......."
For lower frequencys (broadcast band) a 1/4 wave vertical is very long.
At 1000 KHZ, it would be 234 feet. This necessitates mounting the
antenna on the ground. The only place they can put the radials is in
the dirt, this creates a lot of ground losses to the RF. Remember that
in a groundplane antenna, the groundplane is the other half of the
antenna. You then have RF flowing through the radials, and if they are
in or on the ground, the earth losses will be high. The losses depend
on the conductivity of the soil. Salt water has the lowest losses of
any material, salty marshes would be next, various soils have varying
conductivity. The more you eleveate an antenna above ground, the lower
the losses will be, and the fewer radials will be needed to do the same
job of the standard for ground mounted verticals, which is 120 1/2 wave
radials. I assure you a VLF antenna will need all these radials to work
properly. The more you reduce below 120 radials, the less signal you
will get from the system, and the more earth losses.
Also, the above information about a ground mounted dipole having a 0
degree radiation angle is not accurate. A ground mounted dipole has
essentially the same pattern as a 1/4 wave groundplane. The lower half
of the dipole functions just as the groundplane would, and the angle of
radiation is the same as a 1/4 wave groundplane antenna, which has a
higher takeoff angle than a 5/8 wave groundplane.
Codys PC
In article <warnergt-150...@cs2-06.eph.ptd.net>,
warn...@loveboat.com (George Warner) writes:
>Coincidentally, I was just looking in the 1989 ARRL handbook. They
>had a 5/8 wave 220 MHz antenna. That antenna is 28.5" long. My
>calculations show this to be 0.53 wavelengths.
>Why are all these "5/8 wave" antennas 0.53 wavelengths long?
What formula are you using?
Just curious...
:+> Andy <+:
~~~ A note from the Litter box : ~~~~~~~
|\w^w/| *73* to you and yours |\^v^/|
( -- -- ) from all of us..... ( O -- )
` =^=' :+> Andy and Alpha<+: `=^='
Squeaky =======&========Screamy
The Feline controlling interests...;-)
AL7KB
Joe Bennett GJ0NYG wrote:
>
> This does look fun....
> Right, a vertical antenna is as efficient as it's RADIATING length with
> respect to the
> current flowing along it. A 17 foot long CB antenna is a half-wave,
> impedance at the base
> several Kohms, requiring a matching xformer to connect to 50 ohm co-ax.
> A 21 foot CB
> antenna is a 5/8 wave with an impedance xformer at the base. Due to the
> length of the 5/8
> it does have a slightly higher theoretical gain BUT........
> it needs a perfect ground extending for many wavelenths underneath it.
true, the conductivity around an antenna has a lot to do with an
antennas performance, but a groundplane does not need a perfect ground
for many wavelengths underneath it.
> This gives it the
> extendeded zepp effect by using the earth mirror image. This raises the
> angle of takeoff,
> which is not good for local working. A halfwave however does not need a
> ground plane. In fact
> adding one raises the takeoff angle.... NOT good for local working.
> So....
> A 5/8 needs a perfect ground, so really should be mounted at ground
> level
I think he is used to using lower frequencies since he is using a HAM
callsign, ground mounted verticals are expected on lower frequencies
(1.8MHZ, 3.5MHZ, 7MHZ) because you simply can't raise these verticals
off the ground, especially on 160 and 75 meters. They are too big.
Therefore you must ground mount it and use lots and lots of radials to
reduce the earth losses in the near field of the antenna. You have no
control over the earth losses beyond the near field, and losses are at
the mercy of the ground conductivity in the area. A 5/8 wave CB antenna
does not have this problem, since it's groundplane is attached to the
antenna. 4 radials (tuned) 1/4 wavelength long at 1/2 wavelength above
the ground are as efficient of a groundplane as 120 1/2 wavelength
radials when ground mounted.
> A half wave monopole( end fed vert) needs no ground plane so can be
> raised higher, so giving
> a greater line of site range.
> A 5/8 has a small gain of approx 2dB over a dipole but at a HIGHER angle