Quad Vs Yagi for HF
Ron Stordahl
Lew McCoy in the February 1997 issue CQ write on the issue of antenna
efficiency comparing Quads to Yagis. I recall similar articles on this
subject which reach the same conclusion. That conclusion is that it is
much easier to achieve high efficiency with the Quad. While I have not
compared the two in practice I do concur with him that it is difficult to
maintain low resistance connections with my particular Yagi. Actually I am
rather critical of the manufacturer of my beam, who shall remain nameless.
The feed connection to the antenna has failed me many times.
I would be interested in a Quad for use from 40 m through 10 m (7 bands) if
such a Quad is available, sturdy and not too great a compromise. I may be
asking for the impossible.
Any thoughts on this subject, particularly from existing Quad users (or
former Quad users)?
Ron N5IN
macino
Well Ron,
You asked for it! I don't believe anybody commercially builds
a seven band 40-10 quad. From my personal preference, at my
QTH, antenna height, HAAT, and power,the Quad wins hands down.
On the other hand though, be prepared for the 'mechanics' of
a quad. I found separate feeds work best for each loop. Two
problems are generated. Cost and weight. If you ran 7 feedlines, one of
those two problems might be prohibitive. A
40 meter quad is a pretty big mass to be turning. So be prepared to look
at cost, weight, and size again. That Wal-Mart
Aluminum tower 'ain't gonna get it' with the hulk you are
comtemplating. Don't know where you are in 5 land, and ice might not be
a problem. We get a bunch of it (like yesterday)
in northern Indiana. I cringe every time we get nailed with a
storm. The Moseley has always survived, the Gem Quad has not.
What to do, what to do. Put up a good quality yagi for your
'regular communications' and put up a Quad for 'experimental
communications. You then have two platforms to compare. If the
quad stays up, you'll appreciate the performance of the quad.
If it doesn't, you still have a working antenna.
After all, antennas are about the only things (radio) that most
amateurs still experiment with. Have fun
73 Jim W9LZ
w8j...@aol.com
In article <01bc0c93$a4cc27a0$7920...@stordahl.bus.dkc.com>, "Ron
Stordahl" <r...@digikey.com> writes:
>
>Lew McCoy in the February 1997 issue CQ write on the issue of antenna
>efficiency comparing Quads to Yagis. I recall similar articles on this
>subject which reach the same conclusion. That conclusion is that it is
>much easier to achieve high efficiency with the Quad.
Watch your step, hat sounds like fresh droppings from the bull pasture!
This has been going on for years and years, but real world measurements
and now computer models have never supported those claims.
>While I have not
>compared the two in practice I do concur with him that it is difficult to
>maintain low resistance connections with my particular Yagi. Actually I
am
>rather critical of the manufacturer of my beam, who shall remain
nameless.
>The feed connection to the antenna has failed me many times.
Why not correct the mechanical problem? What keeps breaking?
>I would be interested in a Quad for use from 40 m through 10 m (7 bands)
if
>such a Quad is available, sturdy and not too great a compromise. I may
be
>asking for the impossible.
I think so. If you are unhappy with the construction of the yagi, why not
get another one from another source?
A yagi is traditionally more rugged. It has larger conductors with less
ohmic loss.
There are common misconceptions about radiation resistance (the true
radiation resistance, not the feedpoint impedance). A yagi and quad have
almost identical radiation resistances. Don't swallow the off the wall
claims Lew made about efficiency, they are completely untrue.
73 Tom
Neil Armann
Ron Stordahl wrote:
>
> Lew McCoy in the February 1997 issue CQ write on the issue of antenna
> efficiency comparing Quads to Yagis. I recall similar articles on this
> subject which reach the same conclusion. That conclusion is that it is
> compared the two in practice I do concur with him that it is difficult to
> maintain low resistance connections with my particular Yagi. Actually I am
> rather critical of the manufacturer of my beam, who shall remain nameless.
> The feed connection to the antenna has failed me many times.
>
> such a Quad is available, sturdy and not too great a compromise. I may be
> asking for the impossible.
>
> former Quad users)?
>
once in a while. Both Antenna Mart and Lightning Bolt make a 40 meter
quad and it should be simple to add whatever bands you want. However,
Cebik has in an in depth article coming up in Communications Quarterly
on the interaction of single feed to quads. He is really a guy that is
on the ball and his program showed up some of the pattern degradations
that I have experienced--many time--over many years. It is an easy
problem to solve. I have, over the years, been involved with many gain
measurements of quads and Yagis on really decent antenna ranges--one
thing I have to chuckly about what with advertisements on gain, etc. are
the--forgive the expression "true" facts about Yagi gain, etc.
You may not know this--but NO trap beam has ever exceeded 6.2 decibles
of gain. Even stacking two trap beams does not add gain simply because
the total losses bring the gain back do to 6.2 dB. I know this will
sahke up a lot of readers but these are facts--in working so many years
at ARRL and then at CQ I was always faced with the problem of antenna
advertisers and telling th truth. We all live in a real world but
finally, I got to be 80 years plus--got enough money--so the truth comes
very easy.
Let me know by E mail if you get this. Lew McCoy, W1ICP
w8j...@aol.com
>You may not know this--but NO trap beam has ever exceeded 6.2 decibles
>of gain.
That big NO sounds pretty firm. Where is that data published, or where
were the meaurements made?
A quad is two 1/8 wl long end-loaded "dipoles" stacked 1/8 wl, nothing
more, nothing less. There is no magic. The slight gain advantage of a
quad is largest in free space, and decreases as the antenna becomes larger
or placed near earth.
I'd sure appreciate it if someone could point out where supporting
references can be found, or explain exactly WHY a quad has higher
efficiency (the radiation resistance arguement is certainly not true). I
have found nothing in either theory or practical measurements to support
the advantages claimed for a quad, nor to support the blanket condemnation
of all trap or yagi antennas.
When I look around at commercial antennas used below UHF or SHF, I never
see quads. Only yagi's and logs. Even TV antennas are yagi's. Point to
point VHF antennas are stacked yagi's, not quads.
Why is that, if a quad is so much better?
73 Tom
Ron Stordahl
Neil Armann <NAr...@asu.edu> wrote in article <32EEB6...@asu.edu>...
> You may not know this--but NO trap beam has ever exceeded 6.2 decibles
> of gain. Even stacking two trap beams does not add gain simply because
> the total losses bring the gain back do to 6.2 dB. I know this will
> sahke up a lot of readers but these are facts--in working so many years
> at ARRL and then at CQ I was always faced with the problem of antenna
> advertisers and telling th truth. We all live in a real world but
> finally, I got to be 80 years plus--got enough money--so the truth comes
> very easy.
>
> Let me know by E mail if you get this. Lew McCoy, W1ICP
>
> w1...@ziant.com
>
Lew, very pleased to hear from you. I have been reading your articles ever
since I was originally licensed in 1957 under the call KN0UXQ. The
particular computer you used for your posting is shown as from 'Neil
Armann', perhaps a ham friend.
I am going to look into the 2 companies you mentioned. It would be very
exciting to have real gain on 40M. Currently my beam on 40 is just a
single element, shortened of course. It would be interesting to know just
how much of my power is being radiated as heat, probably quite a bit.
What I will do is gather info from the quad mfgrs and then post what I find
for further discussion. At this point I believe my main concern is the
physical strength of the quad, we have trying weather conditions up here.
Ice, wind, snow, extreme cold, thats Northern Minnesota.
Ron N5IN
Rick Craig, N6ND
"Ron Stordahl" <r...@digikey.com> wrote:
>Neil Armann <NAr...@asu.edu> wrote in article <32EEB6...@asu.edu>...
>> of gain. Even stacking two trap beams does not add gain simply because
>> the total losses bring the gain back do to 6.2 dB. I know this will
>> sahke up a lot of readers but these are facts--in working so many years
>> at ARRL and then at CQ I was always faced with the problem of antenna
>> advertisers and telling th truth. We all live in a real world but
>> finally, I got to be 80 years plus--got enough money--so the truth comes
>> very easy.
>> Let me know by E mail if you get this. Lew McCoy, W1ICP
Lew, you may have made it to 80+ years but some of your antenna screws
came loose along the way. How about posting some facts to back up
these ridiculous claims. Stacking gain for 2 antennas does not
change because the antennas have traps, that's absurd!
Rick, N6ND
cra...@nosc.mil
Alan Schoberg
w8j...@aol.com wrote in article
<19970129184...@ladder01.news.aol.com>...
> In article <32EEB6...@asu.edu>, Neil Armann <NAr...@asu.edu> writes:
>
[ snippers at work]
> When I look around at commercial antennas used below UHF or SHF, I never
> see quads. Only yagi's and logs. Even TV antennas are yagi's. Point to
> point VHF antennas are stacked yagi's, not quads.
>
> Why is that, if a quad is so much better?
>
> 73 Tom
>
I would guess that the relative mechanical ease of maintaining a yagi
outweighs whatever electrical advantage the quad might have.
Glenn Thomas
My newsreader claims that Rick Craig, N6ND (cra...@nosc.mil) wrote:
: Rick, N6ND
: cra...@nosc.mil
I think that this is really a non-issue. Lew refered to a "trap beam" in a
context that clearly indicates HF - and probably 3 elements or so. The
loss in gain has been said to be due to losses of various sort in the traps
themselves. Many years ago, QST printed the story of one poor sould who
almost burned his house down from bit of flameing trap falling off his beam!
(it was in QST, it must be true ;).
3db loss in stacking two trap beams? Maybe if you stacked them for 14MHz
and then did the gain measurment on 10... but on antennas stacked for
20 and measured on 20? 3db is a LOT of loss for a few score feet of
RG-11 at 14MHz! What gives Lou?
73 de Glenn wb6w
--
*********************************************************************
* "Two wrongs don't make a right, but three lefts do." *
* *
* wb...@netcom.com - Glenn Thomas *
*********************************************************************
Roy Lewallen
> You may not know this--but NO trap beam has ever exceeded 6.2 decibles
> of gain. Even stacking two trap beams does not add gain simply because
> the total losses bring the gain back do to 6.2 dB. I know this will
> sahke up a lot of readers but these are facts. . .
When two antennas of any kind are fed and spaced far enough apart that the
fields can completely add (a spacing which depends on the phasing -- for
zero degrees phasing, any distance qualifies), the gain over a single
antenna will be 3 dB, modified by the mutual coupling. In some cases,
mutual coupling increases the gain beyond the 3 dB figure, and in some
cases reduces it. But as a single antenna gets lossier and lossier, the
effect of mutual coupling gets more and more swamped by the loss.
Consequently, the lossier the antenna becomes, the closer the gain of two
of them gets to 3 dB relative to a single one. That is, if you phase two
very lossy antennas, the gain compared to a single antenna of the same
(lossy) sort is 3 dB. The statement that trap losses "bring the gain back
do[wn] to" the gain of a single beam is definitely not a fact.
This is explained in more detail in Chapter 8 of the ARRL Antenna Book.
Roy Lewallen, W7EL
mike....@ziplog.com
Roy I wonder if the statement wasn't expanded out of a "RFreudian" slip
here? He hasn't said, but I'm sure Lew knew enough.. I suspect that what
really happened was that he meant it in terms of what was done with
research on the stuff they did. Since ARRL and CQ, I suspect, never went
for an evaluation of four TH-7's on a rotating tower array or something like
that, I suspect the statement was made in the context of some 40 years
or so worth of whatever they did evaluate, not what they could have if they
bought into Rotating Tower, Inc., up in North Texas.... or owned the Hy-Gain
test range or the Telex research cupola...
:)
//-----------------------------
Mike - W5WQN
Mike....@ziplog.com
MIke....@f3000.n117.z1.fidonet.org
Madjid
w8j...@aol.com wrote:
>
> In article <01bc0c93$a4cc27a0$7920...@stordahl.bus.dkc.com>, "Ron
> Stordahl" <r...@digikey.com> writes:
>
> >
> >efficiency comparing Quads to Yagis. I recall similar articles on this
> >subject which reach the same conclusion. That conclusion is that it is
> >much easier to achieve high efficiency with the Quad.
>
> This has been going on for years and years, but real world measurements
> and now computer models have never supported those claims.
Bismillah arahman arrahiim....
Also sprach the great Ayatollah of the antenna newsgroup!
Amoung the many articles who talk about Quad performance
check this one:
Quad vs Triband Yagi in ARRL antenna anthology 1978
by Col. John H Parrot W4FRU
who after months of rigorous A/B testing of Quad vs Triband beams
concluded:
"One can expect to achive the same or BETTER results with a
2-element Quad of proper dimensions than with a 3 or 4 element
triband Yagi"
Madjid, VE2GMI
No beams here Just Quads.................
Home Page: http://www.CAM.ORG/~mboukri
mike....@ziplog.com
In <19970129184...@ladder01.news.aol.com>, w8j...@aol.com writes:
>In article <32EEB6...@asu.edu>, Neil Armann <NAr...@asu.edu> writes:
>When I look around at commercial antennas used below UHF or SHF, I never
>see quads. Only yagi's and logs. Even TV antennas are yagi's. Point to
>point VHF antennas are stacked yagi's, not quads.
>
>Why is that, if a quad is so much better?
>
>73 Tom
Did HCJB give up on quads, or did the air get denser from all this argument
so that they stopped eating away the tips of the antennas, or did they
simply stop trying to get closer to the rarer regions and settle for a life of
ground pounding where all the frying is perhaps less here and now but more
below?
Or is XX Corona only something that can be put in glass and suppressed?
<The crab is scuttling sideways again..... :)
Mike Del Pozzo
"Ron Stordahl" <r...@digikey.com> wrote:
>Lew McCoy in the February 1997 issue CQ write on the issue of antenna
>efficiency comparing Quads to Yagis. I recall similar articles on this
>subject which reach the same conclusion. That conclusion is that it is
>much easier to achieve high efficiency with the Quad. While I have not
>compared the two in practice I do concur with him that it is difficult to
>maintain low resistance connections with my particular Yagi. Actually I am
>rather critical of the manufacturer of my beam, who shall remain nameless.
>The feed connection to the antenna has failed me many times.
>I would be interested in a Quad for use from 40 m through 10 m (7 bands) if
>such a Quad is available, sturdy and not too great a compromise. I may be
>asking for the impossible.
>Any thoughts on this subject, particularly from existing Quad users (or
>former Quad users)?
>Ron N5IN
Hello Ron,
I have had a 4 element Cubex tribander up for about 1-1/2 yrs now . It
has easilly survived most gusting winds that come through Atlanta. I
will say that I am very pleased with it's performance over the 3 "
Long John " yagis from Hygain. I am a very active contester on the
HF bands ( particullarly DX ) . Many new contacts were made possible
due to the gain difference . Yeh right : a quad V.S. a Yagi. Well
here's the scenario : My quad sits up @ 80 ft. and in order to make
thesame quality QSO's on a yagi ; the Yagi would have to be @ 100 +
feet.
In ocordance with many opinions on the gain differences , I beleive
the Quad will come out in front on these given factors :
1. height above ground
2. ease of "stacking " antennas ( all on one boom & seperately fed )
3. Overall stability of the structure ( ever see the elements curl
back on a yagi W/ 90 MPH gusts ? )
4. matching ( with correct spacing on say 20 mtrs , impedence IS 50
Ohms )
Here are some disadvantages :
1. structure flaws ( highly depends on manufacturer )
2. cannot stack anything above it on same mast ( I have this problem )
3. very difficult to construct ( even a triband Quad - I had to build
standing attop a 10 ft stepladder )
To revise a prior claim of it's contruction : sorry Tom , the antenna
consists of 2 1/2 wave elements stacked end to end for an overall
total of 1 full wavelength ea element.
When someone will be nuts enough to stack quads up a tower for the
superiority of gain enhancement , I have to admit that a good amount
of gain could be acheived easier by stacking " simmiliar " yagis.
Well Ron there you have what I hope will be usefull information from
a Quad - User , One who has been down both alleys and puts his station
to vigorous tests continuously to DX rather than neighbors down the
block...
Keep in mind also that dollar for dollar for true performance Large
Yagis V.S. Quads , Yagis will be slightly cheaper , but let your own
ears and background on both BE the judge.............
Gud Luck es CU in the pileups
73 de KR4TG
Mike
mike....@ziplog.com
In <32F2CA...@cam.org>, Madjid <mbo...@cam.org> writes:
>who after months of rigorous A/B testing of Quad vs Triband beams
>concluded:
>
>"One can expect to achive the same or BETTER results with a
>2-element Quad of proper dimensions than with a 3 or 4 element
>triband Yagi"
>
>Madjid, VE2GMI
>No beams here Just Quads.................
>
>Home Page: http://www.CAM.ORG/~mboukri
Reasonable information, but subject to the same caveate that has always been
present in these discussions. As the element count goeth up much beyond
this for the comparison, the quad falls apart. Beyond 4 or so elements,
the performance of the quad doesn't rise so much as adding the additional
elements to a properly designed yagi.
If you think of the quad as two yagis with the tips bent over and touching
each other, then you realize what is happening. Optimizing beam performance
for stacked arrays requires increasing the spacing, as I understand all this,
as the number of elements increase. Beyond four or so elements in a quad,
the two closely spaced yagis with the tips bend over and touching are too
close to keep getting the incremental performance increase from each
additional loop element that one can get from properly designed additional
yagi element....
Model it with any of the antenna programs... you'll see.
w8j...@aol.com
In article <5cvj3t$b...@camel2.mindspring.com>, kr...@mindspring.com (Mike
Del Pozzo) writes:
>In ocordance with many opinions on the gain differences , I beleive
>the Quad will come out in front on these given factors :
>1. height above ground
No real advantage, after all it is only two 1/4 wl long radiating sections
stacked 1/4 wl.
>2. ease of "stacking " antennas ( all on one boom & seperately fed )
But that adds much interaction. Just like it would stacking yagis a few
feet apart.
>To revise a prior claim of it's contruction : sorry Tom , the antenna
>consists of 2 1/2 wave elements stacked end to end for an overall
>total of 1 full wavelength ea element.
Not true.
The ends fold over, and current is 180 degrees out of phase in each
vertical section and in each half of each vertical section. That virtually
cancels all radiation from the vertical sides (assunming the quad is a
horizontally polarized Quad). It's almost EXACTLY like the sides are not
even there, except the add "loading" to the element.
We are left with two 1/4 WL long end loaded dipoles, stacked 1/4 apart.
If you look at broadside gain charts, you'll see the stacking gain of two
radiators spaced 1/4 wl is about ONE dB. This gain of about one dB, minus
the slight loss due to shortening the length of the radiating area from
1/2 wl to 1/4 wl, is the gain a single quad element in free space. The
total gain is just under one dB over a dipole in freespace.
If the antenna is over earth at a height tending to null the straight up
pattern (let's say 1/2 wl mean height) this one dB advantage decreases.
That's because antennas produce gain by pattern interference, antennas
create "gain" by canceling radiation in one or more areas of the pattern.
The power applied to the antenna has nowhere to go except in the rest of
the lobe (or as increased I^2 R heat). The horizontally polarized quad
gets its gain because the 1/4 wl stack of broadside radiators cancels the
field slightly straight up and down.
If the ground below the antenna, or the length of the antenna
(multi-element quad), puts a null in the direction of straight up and
down, the gain advantage just disappears.
That's why when you stack two yagis, the more direction each yagi is the
wider the stacking distance must be for maximum gain improvement. In a
multi-element quad over earth, the gain advatage is always LESS than the 1
dB freespace gain of two current elements stacked 1/4 wl apart.
When Wayne Overbeck measured a series of HF quads, he found large yagis of
the same size offered better performance. The larger the quad, the better
the same boom size yagi was.
If you look at large multi-element EME arrays, very few or none of the
high performance arrays use quads. They are virtually all yagis. If you
look at large point to point HF arrays, they are arrays of dipoles. None
are quads.
Quads are pretty antennas, they are fun antennas, they give us bragging
rights and something special to talk about, but commercial or max
performance people care less about that. They want the simplest antenna
possible that performs the same or better.
They use arrays of dipoles (like yagis or curtains).
Regarding radiation resistance, a quad has the same radiatiion resistance
of a yagi with the same general size and pattern. Don't confuse feedpoint
resistance with radiation resistance. The quads true radiation resistance,
by the IRE standard method, is 1/4 of the resistance measured at the
feedpoint. A 50 ohm feedpoint resistance quad actually has a radiation
resistance of 12.5 ohms, virtually the same as a yagi of the same sin x/x
pattern.
There is no free radiation resistance lunch, even if it is a box shaped or
twisted up fractal lunch.
73 Tom
David B. Holtkamp (K5KH)
> Lew, you may have made it to 80+ years but some of your antenna screws
> came loose along the way.
You are rude. Didn't your mother teach you to be polite?
Lew McCoy
Fractenna wrote:
>
> Hi Dave--
>
> When I first got on here in the Summer, the second thread I read was about
> some poor fellow who fell off a roof while installing a vertical. He
> really smashed himself up--very badly; apparently he lost his nose.
>
> You'd be amazed how many responses this fellow got; mostly that he got
> what he deserved; was a hoax; and so on. Quite extraordinary.
>
> In any case I present this by illustration that THIS newsgroup is not like
> ragchewing on 20M on a Sunday morning and it's certainly not a mutual
> admiration society. I hardly defend this grotesque attitude but accept
> that there are some real 'individuals' here. As for me, I disagree with
> Lew sometimes, but so what? He's devoted much of his life helping others
> understand antennas and I admire him for it.
>
> So, don't go away Lew; stick with us and filter out the noise.
>
> 73
> Chip N1IR
I suppose I should qualify myself on quads versus Yagis--They both are
darn good antennas--I argue in favor of quads but use a DJ2UT beam. I
would like to see you guys discuss location gain--what would you rate a
good location--3 db--10 db--20 db or even much more. I picked this
spot in New Mexico--6400 feet elevation--just about on the divide, my
tower sits on top an abonded copper mine--ground conductivity is
excellent--what would you say--30 dB gain and over what?
Lew McCoy W1ICP
Fractenna
w8j...@aol.com
In article <01bc105d$783b81e0$8c6d...@internet.roadrunner.com>, "David B.
Holtkamp (K5KH)" <holt...@roadrunner.com> writes:
There is no need for anyone to direct personal insults at another. This
seems to have increased like an infection, since a few people have started
doing it as a habit or defense of wild theories and claims whenever
questioned.
Lets stay technical even if we get real frustrated. I hope the goal is to
learn, and not fight.
73 Tom
David B. Holtkamp (K5KH)
> I suppose I should qualify myself on quads versus Yagis--They both are
> darn good antennas--I argue in favor of quads but use a DJ2UT beam. I
> would like to see you guys discuss location gain--what would you rate a
> good location--3 db--10 db--20 db or even much more. I picked this
> spot in New Mexico--6400 feet elevation--just about on the divide, my
> tower sits on top an abonded copper mine--ground conductivity is
> excellent--what would you say--30 dB gain and over what?
Hi again, Lew!
I think you made an amazingly good choice! But I'm not sure that one can
always plan to be in a good spot based on what one can find out. Take my
location for example:
I'm up in Los Alamos, NM about 7000 ft. The underlying mesa is volcanic
ash (compacted into a pumice like rock called "tuff") and is basically no
ground at all. Best as I can ascertain, ground for me is about 1000 ft
down where the water table of the nearby Rio Grande river is. A friend
told me what the dielectric properties were of the soil and I forget at the
moment, but they are extremely poor.
Having said all that, I get out like gangbusters! Far better than I
deserve to! On 160 and 80 I use a double sized G5RV (102 ft each leg + 68
ft or so feeder) that starts all of 35 feet off the ground near the top of
my little tower. It goes down one way about 45 degrees for a ways and then
doubles almost back along the wooden fence (4 ft off the ground). The
other leg goes along the roof line for 60 ft or so then down to the other
wooden fence and along it for 20 ft or so. I don't know quite why, but I
get good reports from all over the country and have 49 states on 160 now
(run an old TL922 with 500 w usually). If the ground were any good at all,
I think my signals would go straight up and never, ever come back! <smile>
But I don't even try to work 40 m any more because the mismatch couples
lots of current back into the house ground/piping (I've tried radials and
have 8 ft ground rods, but no chemical treatment of the rod/earth
interaction).
I'm just a lucky guy, I guess! Can't wait to replace my old HF log
periodic sometime with a better beam!
Thanks for being here and adding to the discussion!!!
David (K5KH)
David B. Holtkamp (K5KH)
> Lets stay technical even if we get real frustrated. I hope the goal is to
> learn, and not fight.
Sorry to reply to his sarcasm directed at Lew, but I didn't want Lew to
get disgusted and leave. He is a remarkable man and a great contributor to
this forum. I'd bet he's forgotten more about antennas than I will ever
know!
You are absolutely right, Tom. I will try and restrain myself.
Best wishes,
David (K5KH)
David B. Holtkamp (K5KH)
>
> In any case I present this by illustration that THIS newsgroup is not
like
> ragchewing on 20M on a Sunday morning and it's certainly not a mutual
> admiration society.
Hmmmf...If only the ragchewing I hear on 20 m (or, more graphically 75 m)
resembled the discussions here! They would improve in SNR!!!
You are right, Chip. I shouldn't have whacked him. You should have seen
my message before I toned it down! <g>
Best wishes,
David (K5KH)
Hal Rosser W4PMJ
mike....@ziplog.com wrote:
> , Neil Armann <NAr...@asu.edu> writes:
>
> >When I look around at commercial antennas used below UHF or SHF, I never
> >see quads. Only yagi's and logs. Even TV antennas are yagi's. Point to
> >point VHF antennas are stacked yagi's, not quads.
> >
> >Why is that, if a quad is so much better?
> >
to construct yagis. and the average antenna buyer wants
something that can fold out easily and be easy to install.
Quads give more gain per boom foot, but because they are
three dimensional, are harder to assemble and install.
I've tried both and prefer the added gain of the quad,
but I understand they can be tough to put up for the
average joe. ANyway, that's my opinion, for what it's worth.
HAL W4PMJ
hmro...@csranet.com
Fractenna
Hi Dave--
You are certainly not someone who would tell someone in an accident that
they got what they deserved! But there are those around...
73
Chip
w8j...@aol.com
In article <01bc1151$3628d4c0$9f6d...@internet.roadrunner.com>, "David B.
Holtkamp (K5KH)" <holt...@roadrunner.com> writes:
>
> You are absolutely right, Tom. I will try and restrain myself.
Actually I should too. It seems that we all get caught up in taking a
technical discussion group as a personal commentary group.
I want to clarify that when I call something bunk, or disagree with
something, it does not mean I intend to paint the writer as stupid. Every
one of us has blind spots. The problem I have is only with the folklore
that misleads people, not the people exposed to it or repeating it.
73 Tom
w8j...@aol.com
In article <32F75A...@csranet.com>, Hal Rosser W4PMJ
<hmro...@csranet.com> writes:
>I suspect the commercial antenna builders find it cheaper
>to construct yagis. and the average antenna buyer wants
>something that can fold out easily and be easy to install.
I was not as clear as I should have.
By commercial installation I meant professional as opposed to amateur
radio. In that case, manufacturing cost is a minor part of the equation.
For VHF point to point, or HF point to point communications, no one uses
quads. Neither VOA or radio Moscow use quads, and even Motorola doesn't do
it in VHF or UHF point to point installations on frequecies where the quad
is very practical.
Aside from perhaps HCJB , I can't think of one commercial HF or VHF point
to point array using a quad. The only place I see quads used on any kind
of remotely common basis is in amateur radio.
73 Tom
JMcAulay
In article
<01bc0c93$a4cc27a0$7920...@stordahl.bus.dkc.com>,
"Ron Stordahl" <r...@digikey.com> wrote:
<snip>
>I would be interested in a Quad for use from 40 m through
10 m (7 bands) if
>such a Quad is available, sturdy and not too great a
compromise. I may be
>asking for the impossible.
>
>Any thoughts on this subject, particularly from existing
Quad users (or
>former Quad users)?
>
>Ron N5IN
I believe the consensus will be that a quad will outperform
a Yagi in almost every respect except staying aloft.
Unfortunately, this is an important consideration.
73
John WA6QPL
w8j...@aol.com
>
>I believe the consensus will be that a quad will outperform
>a Yagi in almost every respect except staying aloft.
>Unfortunately, this is an important consideration.
The problem is there is no consensus. In practical real world
measurements, done in real installations, the opposite has been proven.
Practical large yagi's outperform similar sized quads.
73 Tom
Lew McCoy
element Yagi--I know you are probably generalizing, as I am, but taking
spacing, tuning, etc., the quad has more gain quite simple because it
uses full wave loops versus half wave--the old case of bigger is better.
So, element for element the quad is always favored but I agree, large
quads from a practical standpointcan be a problem.
This is just not conjecture because as I have pointed out, this is
reputable test range measurements.
Lew Mc coy, W1ICP
Anselmo Stiffan
Why not a single element quad? If you build it as per the "Big Kahuna"
described by WA6QBU in April 94 QST magazine, you will cover with a loop as
small as 52 feet all the bands....down to 1.8 MHz. I just buildt a smaller
one of 28 feet and I can cover all bands from 3.5 to 28 MHz with excellent
reports. Last but not least, it's already very effective at 10 feet from
ground. Directivity is like a dipole but with the low noise characteristic
of a quad or a loop.
73,
Anselmo.
W6KKT
On 12 Feb 1997 13:06:43 GMT, w8j...@aol.com wrote:
>In article <5dmvat$j...@mandolin.qnet.com>, j...@qnet.com (JMcAulay) writes:
>
>>
>>I believe the consensus will be that a quad will outperform
>>a Yagi in almost every respect except staying aloft.
>>Unfortunately, this is an important consideration.
>
>The problem is there is no consensus. In practical real world
>measurements, done in real installations, the opposite has been proven.
>Practical large yagi's outperform similar sized quads.
>
>73 Tom
Hi Tom, surely, you are not including tri-band quads with tri-band
yagi's. Everything equal, the multi-band quad will outperform the 3el
multi-band Yagi.
K6UMB, is doing and has done many side by side monoband 4el quad / 5el
Telerex Yagi comparisons. The quad is a Cubex 20m ,4el (30'boom), and
the Telerex 20m model 5M46 (46' boom). Both ants are on seperate
towers with mean heights of 75' and seperated by 90'. Over years of
test compararisons Jay says "there is no discernible difference on
xmit/receive". The quad has no matching device (50 ohm hardline
direct connection). The quad is tuned for max fwd gain and shows a
slight decrease in F/B compared to the Yagi. However, the Quad F/S is
better. For same take off angle the quads top element needs to be
higher than the mean height of the Yagi.
You and Bill Sabins radiation resistance threads have been most
informative.
Respectfully, Jesse, W6KKT
Ted
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* The email address in my "From" header is incorrect! *
* It was changed to defeat spam-bots that send email. *
* To email me, please use my CORRECT email address: *
* *
* Email : t...@caprica.com *
* Webpage: http://www.caprica.com/~ted *
* *
* My Email is neither a newsgroup or a public forum! *
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* sends unsolicited advertizing via Email risk prompt *
* cancelation of internet service without refund and *
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On 12 Feb 1997 w8j...@aol.com wrote:
> Practical large yagi's outperform similar sized quads.
Tom,
I dunno what you've been drinking, but I hope you have a designated
driver. You're totally incorrect.
w8j...@aol.com
>
>Hi Tom, surely, you are not including tri-band quads with tri-band
>yagi's. Everything equal, the multi-band quad will outperform the 3el
>multi-band Yagi.
I can't speak for trap yagis or multi-band quads Jessie. It's out of the range of things I know as facts. There's a lot going on. While the yagi has trap losses, we really don't know how much they are. The quad also has multiple wires all hanging in the worse possible configuration around the wires in use, and we have no idea how that degrades performance.
I sure would never take one measurement of one sample antenna, made under what sounds like poor tests conditons, and draw the conclusion every trap antenna in the world is crummy.
One sure fact is the advantage of a single quad element over a dipole is about one dB. It is also a fact that one dB advantage disappears as the antenna is made more directive, or placed over ground. I'm not saying someone can't build an antenna WORSE than theoretically possible, but is an absolute truth they can't build one BETTER than theory allows.
It would take about five minutes to measure a trap on the bench, and then losses could be determined instead of guessing by looking at the appearance.
>K6UMB, is doing and has done many side by side monoband 4el quad / 5el
>Telerex Yagi comparisons. The quad is a Cubex 20m ,4el (30'boom), and
>the Telerex 20m model 5M46 (46' boom). Both ants are on seperate
>towers with mean heights of 75' and seperated by 90'. Over years of
>test compararisons Jay says "there is no discernible difference on
>xmit/receive".
I would expect that. With equal tuning for max f/b ratio the yagi should be a bit better for gain, but in this case the quad is tuned for maximum gain. When tuned for maximum gain, the pattern sides are pulled in on ANY antenna. Every bit of what he said makes absolute sense when compared to how antennas really work.
73 Tom
w8j...@aol.com
>Directivity is like a dipole but with the low noise characteristic
>of a quad or a loop.
Why does a quad or loop have low noise?
73 Tom
w8j...@aol.com
Hi Lew,
In article <3301FD...@zianet.com>, Lew McCoy <mc...@zianet.com> writes:
>I cannot agree--a four element quad will have more gain than a four
>element Yagi--I know you are probably generalizing, as I am, but taking
>spacing, tuning, etc., the quad has more gain quite simple because it
>uses full wave loops versus half wave--the old case of bigger is better.
Not a good supporting argument at all Lew. Bigger antenna's certainly do not have more gain by virtue of size. For example:
1.) VOA has curtain arrays that occupy a very small fraction of the area of big Rhombics, yet the curtains produce much more gain.
2.) A 2 element broadside dipole array requires about 1/2 wl of center to center spacing to produce 3.8 dB of gain, in collinear arrangement these elements require .9 wl center to center spacing to produce 3 dB of gain, a two element end fire array has 4.5 dB gain with 1/8 wl spacing. The smallest area antenna produces much more gain!
I can't argue personal opinions or religion Lew. Facts are facts.
The gain offered by stacking two elements 1/4 wl apart broadside is one dB under absolutely perfect conditions. Either Jasik, Kraus, Jordan, Termin, Balmain, Kuecken, and others are wrong, or the quad offers LESS than one dB advantage under the ideal case.
While it is possible to build an antenna with LESS than ideal gain, it is impossible to build one with more gain than science supports.
73 Tom
Lew McCoy
Tom: I am not sure of the exotic (?) technical reasons but a quad is a
low noise antenna. Rain and snow static will knock heck out of a
yagi--as I have experienced the noise bit many times--while a quad loop
is quiet. They always refer to a quad as a low Q antenna while a Yagi
as high Q--if I understand that-- I suppose there is some noise
coupling effect of the different Qs.
Lew mcCoy, W1ICP
Cecil Moore
Lew McCoy wrote:
>
> w8j...@aol.com wrote:
> >
> > In article <anselmos-1...@portge57.worldcom.ch>, anse...@worldcom.ch (Anselmo Stiffan) writes:
> >
> > >Directivity is like a dipole but with the low noise characteristic
> > >of a quad or a loop.
> >
> > Why does a quad or loop have low noise?
> >
> > 73 Tom
>
> low noise antenna.
Hi Lew, It has been my experience here in AZ that any antenna with a
DC path between the feedline wires is less noisy than one without a
DC path between the feedline wires. If a static charge is allowed to
build up on an antenna, it is a lot more noisy. I have run A/B tests
on the same dipole fed with a 1:1 balun (no DC path) and a 4:1 balun
(with DC path) and the 4:1 balun resulted in less noise than the 1:1.
With the 1:1 I occasionally got arcing at the coax connector on the
transceiver which was kinda scary. With the 4:1 I never get arcing.
The high winds and low humidity may make AZ a special case but that
has been my experience here.
73, Cecil, W6RCA, OOTC
Fractenna
Hi Tom--
I have done some of the modeling you suggest and regret that, in a
practical sense, I cannot accept your interpretation about gain
non-differences. Here are the model results (field strengths) for a dipole
and a (1 el) Quad with #12 wire at resonance:
Antenna Height Gain(dbi) Launch
Angle(degr)
Dipole free 2.08
---
Quad free 3.24 --
Dipole 1/2 wave 8.48 31
Quad 1/2 wave 8.53 26
Dipole 1 wave 8.12 15
Quad 1 wave 9.14 13
Note that the CENTER of the quad was placed at the height listed. The quad
always has higher gain and lower launch angle.
All the ham antenna books I have seen tout the quad as a DX antenna,
usually for HF. All say the advantage is about a dB. Now, anyone who want
to work DX will try NOT to place place a DX antenna at 1/2 wave, as you
suggest. They will go higher for a lower launch angle. Hence although you
are technically correct, you have CHOSEN a VERY specific example to shore
up your case when, in general, a practical antenna would be placed higher
(such as a 20M quad) and get the dB of gain as advertised.
In essence, I see nothing from this simple analysis that in anyway
degrades the information published in the ham antenna books regarding the
practical gain differences between the quad loop and a dipole. Whether
this one dB is a prize to be sought is a matter of taste. In any case, no
'myth' is afoot in the general understanding of these two antennas from a
comparative sense.
73
Chip N1IR
Roy Lewallen
In article <330401...@ccm.ch.intel.com>,
Cecil Moore <cecil_...@ccm.ch.intel.com> wrote:
>Lew McCoy wrote:
>. . .
>> I am not sure of the exotic (?) technical reasons but a quad is a
>> low noise antenna.
>
>Hi Lew, It has been my experience here in AZ that any antenna with a
>DC path between the feedline wires is less noisy than one without a
>DC path between the feedline wires. If a static charge is allowed to
>build up on an antenna, it is a lot more noisy. I have run A/B tests
>on the same dipole fed with a 1:1 balun (no DC path) and a 4:1 balun
>(with DC path) and the 4:1 balun resulted in less noise than the 1:1.
>. . .
Pardon my ignorance. Why can't the DC path be accomplished with an RF choke
or a high-value resistor? It should be easy to run A/B tests with and
without an RF choke or resistor to see if there's a difference. It seems
that would introduce fewer variables. (I'd do it, but this is a very
low-static environment here.)
If the noise difference between these antennas is only caused by the quad's
DC path, and you can accomplish the same thing with an RF choke or
resistor, it certainly doesn't seem to be more than a trivial advantage.
Roy Lewallen, W7EL
Cecil Moore
Roy Lewallen wrote:
> If the noise difference between these antennas is only caused by the quad's
> DC path, and you can accomplish the same thing with an RF choke or
> resistor, it certainly doesn't seem to be more than a trivial advantage.
Hi Roy, A conventional loop is less prone to static buildup than a
conventional dipole *at my QTH* and I just guessed that might be the
source of the idea. An RF choke or resistor would surely work but
my 4:1 balun does the job so nothing else is needed. When I first
got a G5RV years ago, the static buildup was so bad that I could
hear arcing inside my transceiver every time the wind got over 20mph.
IMO, arcing inside my transceiver is not trivial and I feel a lot
better with the 4:1 balun bleeding the coax to ground.
73, Cecil, W6RCA, OOTC
Don Phelps
(Anselmo Stiffan)
An> Why not a single element quad? If you build it as per the "Big Kahuna"
An> described by WA6QBU in April 94 QST magazine, you will cover with a
An> loop as small as 52 feet all the bands....down to 1.8 MHz. I just
An> buildt a smaller one of 28 feet and I can cover all bands from 3.5 to
An> 28 MHz with excellent reports. Last but not least, it's already very
An> effective at 10 feet from ground. Directivity is like a dipole but with
An> the low noise characteristic of a quad or a loop.
Anselmo,
Could you give description of this antenna for 3.5 to 28 MHz
construction and comparison to dipole performance? Thanks.
... Don.P...@Infoway.com 1:125/104 POBox 9739 San Rafael,CA 94912
___ Blue Wave/386 v2.30 [NR]
Fractenna
Sorry; one more comment on the single loop vs dipole modeling: If the same
quad is allowed to have its feed vertically oriented , we get vertical
linear polarization (as we all know :-) ). We also pick up that gain
difference:
Antenna height dbi launch angle
Dipole 1/2 wave 8.4 31
Quad 1/2 wave 9.6 0
So, my apologies Tom; perhaps we CAN use 1/2 wave as a comparative height.
Here the quad outshines the (horizontal) Yagi by 1.2 dB ;-) .
I welcome somone else's modeling over less than perfect ground.
73
Chip N1IR
Mike Del Pozzo
w8j...@aol.com wrote:
>In article <anselmos-1...@portge57.worldcom.ch>, anse...@worldcom.ch (Anselmo Stiffan) writes:
>>Directivity is like a dipole but with the low noise characteristic
>>of a quad or a loop.
>Why does a quad or loop have low noise?
>73 Tom
Hello Agn Tom,
Can't tell you why exactly why a quad has less noise than a dipole,
but Listening to the difference between the hygain 205CA and the
Cubex 4 el is phenominal . You really could hear stations & work em
well past most people could. I also could hear weak signals well into
the late evening from all over. Not to mention the same scenario very
early in the morning into Europe before the Band REALLY opens.
I wish I could tell you for my own understanding. I know I'll miss my
Quad when it comes down this year , But I have more to stack up there
73 , de
Mike KR4TG
Single Op , All Band , Low Power
Roy Lewallen
In article <19970215002...@ladder01.news.aol.com>,
That's absolutely necessary in order to reach any sort of conclusion. [I'm
sure that's the reason for the ;) -- I'm posting this for people who might
not realize what it was for.] While the ground quality makes little
difference to horizontally polarized waves (except at very high reflection
angles), it makes a major, major difference when the waves are vertically
polarized. Results of modeling a vertically-polarized antenna over perfect
ground are of no practical use unless the reflection takes place over salt
water. This is because they differ dramatically from what you'll ever see
with a real antenna (except over salt water). This is easily demonstrated
by modeling a simple vertical antenna over perfect ground, then real ground
of various qualities, and superimposing the resulting elevation patterns. I
always use this illustration in my talks on antennas and on antenna
modeling. If you use EZNEC, select MININEC-type ground to remove the effect
of resistive ground system loss.
Roy Lewallen, W7EL
Fractenna
A 'winky' again Roy; you read my short hand!
73
Chip N1IR
Richard W. Clark
w7...@teleport.com (Roy Lewallen) wrote:
snip
>modeling. If you use EZNEC, select MININEC-type ground to remove the effect
>of resistive ground system loss.
>Roy Lewallen, W7EL
Hi Roy,
To remove the effect of resistive ground system loss? Isn't that the same
as modeling in free space? I've re-read your entry on ground in the
documents for EZNEC, and am somewhat baffled. I've used Real/MININEC
Analysis largely due to a warning message generated when I chose Real/High
Accuracy for a test. I've long since forgotten the message or what test I
was performing. I'll admit this is a naive user approach, but your last
comment above makes it difficult to know what is included and what is not.
There are times I am principally interested in the accuracy of the drive
point impedance, and I could care less about patterns. Then there are
those times I want accuracy in the patterns, but could care less about
drivepoint impedance (as long as its computation did not impact on the
pattern accuracy). In all respects I need a clear and consistent
differentiation between real and loss-less modes of analysis. The
statement from your EZNEC documentation:
The MININEC-type ground considers the ground to
be perfect when calculating the impedances and currents.
doesn't sound like real ground to me, and gives me no confidence in drive
point impedance derivations. I want to know how ground will perturb
impedance.
The MININEC-type
ground leads to the fastest calculation times, and is
satisfactory if the antenna doesn't contain any horizontal
wires which are lower than about 0.2 wavelength
I must assume this rules out verticals modeled with raised radials (when
the radials are less than 0,2 wl in elevation?)?
But then later you state:
The High-Accuracy ground is the most accurate for antennas with
low horizontal wires.
But the High-Accuracy ground is a MININEC-type ground which isn't
satisfactory for wires below 0.2 wl
This is all confusing with mutually exclusive statements and the
commingling of real ground with perfect ground.
So, to put it simply, for drive point impedance modeling:
1.)Which ground type yields a model of real-world losses?
2.)What factors deteriorate accuracy?
and, for pattern modeling:
3.)Which ground type yields a model of near real-world losses?
4.)What factors deteriorate accuracy?
73's
Richard Clark, KB7QHC
Roy Lewallen
In article <5e6b2i$c...@q.seanet.com>,
rwc...@rwclark.seanet.com (Richard W. Clark) wrote:
>w7...@teleport.com (Roy Lewallen) wrote:
(I'll answer this in the newsgroup rather than email because it applies
equally to other modeling programs.)
>To remove the effect of resistive ground system loss? Isn't that the same
>as modeling in free space?
No. MININEC-type ground gives you a zero-ohm connection to a ground plane.
This is not the same as free space, where there is no ground plane.
> I've re-read your entry on ground in the
>documents for EZNEC, and am somewhat baffled. I've used Real/MININEC
>Analysis largely due to a warning message generated when I chose Real/High
>Accuracy for a test. I've long since forgotten the message or what test I
>was performing. I'll admit this is a naive user approach, but your last
>comment above makes it difficult to know what is included and what is not.
Several calculations take place in these programs. First, the mutual
impedances are calculated between each segment and every other one. Then,
using the source voltages or currents, the currents on the segments are
calculated. Finally, the field is determined from the currents. In this
last step, the effect of reflection of the signal off the ground is
included.
Let's take the last step first. With free-space analysis, there's no
ground, so no reflected component. With "perfect" ground, the ground is
just that, and all reflections are perfect. Using this ground will give you
the classic maximum-at-the-horizon pattern for a vertical antenna, for
example. Then there are "real" ground choices, 3 in EZNEC. All these
operate the same for ground reflection. They calculate the reflection
coefficient for the impinging wave (which depends on its polarization), and
add the reflected wave (as modified by the reflection coefficient) to the
non-reflected wave to determine the overall pattern. This is the same as
for perfect ground except for the inclusion of the reflection coefficient
in the calculation. If you look at the same vertical with perfect ground,
then with "MININEC"-type "real" ground, you see only the effect of the
ground reflection. Which can be very significant. OK so far?
The "real" ground types differ in how ground is used during the Z and
current calculation. "MININEC" ground assumes that the ground is perfect
during these calculations. Therefore, if you connect a wire to ground, the
connection resistance is zero, just as it would be for a perfect ground
plane. "MININEC" ground shows you the effect of imperfect reflection from
the ground (as explained in the previous paragraph), but zero-ohm
connection to the ground. This is the approach taken in MININEC, hence the
name. The disadvantage of this analysis type is that it'll give inaccurate
values for the feedpoint impedance, currents, and fields from horizontal
wires lower than about 0.2 wavelength. This is because of its simplifying
assumption that the antenna is over perfect ground during Z and I
calculations.
The "real" ground type EZNEC calls "fast analysis" is the NEC-2
reflection-coefficient method. It uses the real ground conductivity and
permittivity during Z and I calculation, but with a simplified method. It
gives inaccurate results for horizontal wires lower than about 0.1
wavelength. Connections to ground using this method will result in an
unpredictable impedance at the connection point. This is because it can't
model wires below the ground, and what constitutes the "connection" of the
end of a wire to dirt is pretty tenuous.
Finally, EZNEC "high-accuracy" ground is NEC-2 Norton-Sommerfeld ground.
It's the most accurate in calculating the actual Z and I you'd get over a
real ground, but takes longer to calculate. It's accurate even for very low
horizontal wires -- down to about 1/1000 wavelength. But it too will give
an unpredictable impedance at the connection point.
>There are times I am principally interested in the accuracy of the drive
>point impedance, and I could care less about patterns.
If your drive point impedance involves connections to ground systems,
there's no way to get a really accurate answer with any NEC-2 based
program. The best you can do is use MININEC ground and add the estimated
ground system resistance as a "load", or model buried radials as wires very
slightly above the surface of the ground.
> The MININEC-type
> ground leads to the fastest calculation times, and is
> satisfactory if the antenna doesn't contain any horizontal
> wires which are lower than about 0.2 wavelength
>
>I must assume this rules out verticals modeled with raised radials (when
>the radials are less than 0,2 wl in elevation?)?
Actually, I've discovered that it's more tolerant of radials, which have
opposing currents, than dipoles and other effective radiators. However,
"high-accuracy" ground is definitely the best choice for analyzing elevated
radial systems.
>
>But then later you state:
> The High-Accuracy ground is the most accurate for antennas with
> low horizontal wires.
>But the High-Accuracy ground is a MININEC-type ground which isn't
>satisfactory for wires below 0.2 wl
>
>This is all confusing with mutually exclusive statements and the
>commingling of real ground with perfect ground.
>
>So, to put it simply, for drive point impedance modeling:
>
>1.)Which ground type yields a model of real-world losses?
None, if buried wires or connections to "ground" are involved. If not, the
"high-accuracy" ground is best.
>2.)What factors deteriorate accuracy?
The above explanation is about the best I can do toward answering that.
>and, for pattern modeling:
>
>3.)Which ground type yields a model of near real-world losses?
All the "real" ground types are equally good at this.
>4.)What factors deteriorate accuracy?
Again, the above explanation is about the best I can do.
Roy Lewallen, W7EL
Richard W. Clark
Hi Roy,
Thanks for taking the time to get into the intracacies of this.
w8j...@aol.com
>
>I have done some of the modeling you suggest and regret that, in a
>practical sense, I cannot accept your interpretation about gain
>non-differences. Here are the model results (field strengths) for a dipole
>and a (1 el) Quad with #12 wire at resonance:
>
>
You should re-read what I said Chip.
I plainly said the maximum gain difference is about one dB,
and not the two dB or more touted.
You have confirmed that.
I also said as the array is made larger, the one dB advantage disappears.
That is also a true statement that I'm sure the modeling program
will confirm (if the input data is properly made).
The stuff about day and night differences is bunk. A ham would be hard
pressed to notice three dB difference without a A-B test, let alone one dB
or less.
73 Tom
Richard W. Clark
w8j...@aol.com wrote:
>In article <19970214142...@ladder01.news.aol.com>, frac...@aol.com (Fractenna) writes:
>>
>>I have done some of the modeling you suggest and regret that, in a
>>practical sense, I cannot accept your interpretation about gain
>>non-differences. Here are the model results (field strengths) for a dipole
>>and a (1 el) Quad with #12 wire at resonance:
>>
>>
>You should re-read what I said Chip.
>I plainly said the maximum gain difference is about one dB,
>and not the two dB or more touted.
>You have confirmed that.
>I also said as the array is made larger, the one dB advantage disappears.
>That is also a true statement that I'm sure the modeling program
>will confirm (if the input data is properly made).
Tom, if you don't trust others to input data that is (or is not) properly
made, why don't you do it yourself and give us the results?
>The stuff about day and night differences is bunk. A ham would be hard
>pressed to notice three dB difference without a A-B test, let alone one dB
> or less.
>73 Tom
Hi Tom,
You are right, Chip should have read your posting of:
>the quad offers LESS than one dB advantage under the ideal case.
complete with your emphasis on LESS.
Chip should not have responded with:
>Antenna Height Gain(dbi) Launch
>Angle(degr)
>
>Dipole free 2.08
>---
>Quad free 3.24 --
>
>Dipole 1/2 wave 8.48 31
>Quad 1/2 wave 8.53 26
>
>Dipole 1 wave 8.12 15
>Quad 1 wave 9.14 13
because it clearly took more effort and it shows MORE than 1 dB difference.
Chip even allows what does 1 dB really matter? and you thump away on it
like it was out of your own hymnal. Other oddities include your leaning on
the wheeze "under the ideal case." Tom, you've beat up Chip too often for
using this criteria to hide behind it now.
Arguing both sides of the issue again? Are you sure you aren't just taking
up bandwidth?
Jari Jokiniemi
In article <19970217154...@ladder01.news.aol.com> w8j...@aol.com writes:
The stuff about day and night differences is bunk. A ham would be hard
pressed to notice three dB difference without a A-B test, let alone one dB
or less.
Might well be that when one only rag chews one does not notice a
difference of three dB. My experiences with linear amplifiers have
made me to believe that in a pile-up a three dB difference is indeed
significant. It is then only matter of taste if having a QSO and not
having a QSO is a day and night difference or only a minor
difference.
I have also begun to believe that much more differences are to be
attributed to antenna height rather than the antenna itself. A tower
of some 12 meters or so is not the one to be chosen for chasing
dx in HF. When you have the same HF antenna some 30 meters high the
practical difference to dx is in the order of 10 to 20 dB. This is
something quite impossible to achieve by having more and better elements.
--
Jari Jokiniemi, jari.jo...@tekla.fi, OH2MPO, OH3BU
Tekla Oy, Koronakatu 1, 02210 Espoo, +358-9-8879 474
w8j...@aol.com
>
>You are right, Chip should have read your posting of:
>>the quad offers LESS than one dB advantage under the ideal case.
>complete with your emphasis on LESS.
I'm sorry Richard, can you copy the whole area statement I made,
so I can read it? Then I can respond to your question.
73 Tom
Fractenna
Yeh Jari; changing that launch angle definitely gives the edge!
73
Chip N1IR
Richard W. Clark
w8j...@aol.com
>>I'm sorry Richard, can you copy the whole area statement I made,
>>so I can read it? Then I can respond to your question.
>
>>73 Tom
>
>Hi Tom,
>
>It is the material you snipped out for this response.
>
>73's
>Richard Clark, KB7QHC
I'm sorry Richard,
You misunderstand my request.
That is too small an abstract, so I don't know what context
or what post my statemnt was extracted from. Can you copy
and post the entire area of my statement, or give a message
number so I can see what text you pulled it from?
I can't tell what I was referring to from that little snip alone.
I can repeat my postion if it will save time.
The maximum gain of a quad element over a dipole element is
about one dB under ideal conditions. If the array is made longer
(more directional) or placed over earth, the difference can only be
LESS than about one dB. The quad can never have more than the
freespace maximum advantage of about one dB, unless the textbooks
are wrong, and field and pattern multiplication theory has been wrong for
many years.
I hope this answers your question, and we can move on to more useful
topics. My only point was the claims of phenominal gain, or even gain
that is noticable outside of an A B test, can only be due to one antenna
working POORER than possible. It is definately not because one antenna
offers magical gain.
73 Tom
Richard W. Clark
w8j...@aol.com wrote:
>In article <5ecsel$k...@q.seanet.com>, rwc...@rwclark.seanet.com (Richard W. Clark) writes:
>>>I'm sorry Richard, can you copy the whole area statement I made,
>>>so I can read it? Then I can respond to your question.
>>
>>>73 Tom
>>
>>Hi Tom,
>>
>>It is the material you snipped out for this response.
>>
>>73's
>>Richard Clark, KB7QHC
>I'm sorry Richard,
>You misunderstand my request.
>That is too small an abstract, so I don't know what context
>or what post my statemnt was extracted from. Can you copy
>and post the entire area of my statement, or give a message
>number so I can see what text you pulled it from?
>I can't tell what I was referring to from that little snip alone.
OK Tom here is what you snipped out (try DejaNews if you don't keep track
of your own writing):
**************************************************************************
**************************************************************************
w8j...@aol.com wrote:
>In article <19970214142...@ladder01.news.aol.com>, frac...@aol.com (Fractenna) writes:
>>
>>I have done some of the modeling you suggest and regret that, in a
>>practical sense, I cannot accept your interpretation about gain
>>non-differences. Here are the model results (field strengths) for a dipole
>>and a (1 el) Quad with #12 wire at resonance:
>>
>>
>You should re-read what I said Chip.
>I plainly said the maximum gain difference is about one dB,
>and not the two dB or more touted.
>You have confirmed that.
>I also said as the array is made larger, the one dB advantage disappears.
>That is also a true statement that I'm sure the modeling program
>will confirm (if the input data is properly made).
Tom, if you don't trust others to input data that is (or is not) properly
made, why don't you do it yourself and give us the results?
>The stuff about day and night differences is bunk. A ham would be hard
>pressed to notice three dB difference without a A-B test, let alone one dB
> or less.
>73 Tom
Hi Tom,
You are right, Chip should have read your posting of:
>the quad offers LESS than one dB advantage under the ideal case.
complete with your emphasis on LESS.
Chip should not have responded with:
>Antenna Height Gain(dbi) Launch
>Angle(degr)
>
>Dipole free 2.08
>---
>Quad free 3.24 --
>
>Dipole 1/2 wave 8.48 31
>Quad 1/2 wave 8.53 26
>
>Dipole 1 wave 8.12 15
>Quad 1 wave 9.14 13
because it clearly took more effort and it shows MORE than 1 dB difference.
Chip even allows what does 1 dB really matter? and you thump away on it
like it was out of your own hymnal. Other oddities include your leaning on
the wheeze "under the ideal case." Tom, you've beat up Chip too often for
using this criteria to hide behind it now.
Arguing both sides of the issue again? Are you sure you aren't just taking
up bandwidth?
73's
Richard Clark, KB7QHC
**************************************************************************
**************************************************************************
There you are Tom. I don't expect an answer anymore because you've already
proven that out.