How to Connect Phased Verticals?
Bob Sikes
"Practical Antenna" book. He describes using two 1/4 wave verticals
separated by 1/2 wave and feed at the bottom by equal lengths of coax which
connect to the feedline in the center. My puzzle is how long to make the
pair of equal feedlines? The obvious answer is 1/4 wave, but if I cut
allowing for velocity factor, the lines won't reach!
I then decided that it didn't matter as long as the lines were equal the
verticals would be feed in phase, but a friend suggested that I should use
odd multiples of 1/4 wave to make sure that the impedance is correct at the
T-connector. That's fine except it adds a lot of extra coax which I try to
avoid.
How long should those phasing lines be?
73s
Bob
W1MMM
Goldreged
odd multiples of 1/4 wave to make sure that the impedance is correct at the
T-connector. That's fine except it adds a lot of extra coax which I try to
avoid.>>
The extra coax should not be much of a hinderance, for you now have Gain in the
antennas.
Ed G.
KB1DQX
(Please Remove "JUNKBLOK" to E-mail.
Unless it's a Flame.)
Brooke Clarke
It doesn't matter. This is because a phased array is just a special case of
the more general time delay beam steared antenna. See the Fenwick patent link
on my web page.
http://www.pacific.net/~brooke/electron.html#Antenna
73,
Brooke
Bob Sikes wrote:
> I'm playing around with the phased vertical array described in Carr's
> "Practical Antenna" book. He describes using two 1/4 wave verticals
> separated by 1/2 wave and feed at the bottom by equal lengths of coax which
> connect to the feedline in the center. My puzzle is how long to make the
> pair of equal feedlines? The obvious answer is 1/4 wave, but if I cut
> allowing for velocity factor, the lines won't reach!
>
> I then decided that it didn't matter as long as the lines were equal the
> verticals would be feed in phase, but a friend suggested that I should use
> odd multiples of 1/4 wave to make sure that the impedance is correct at the
> T-connector. That's fine except it adds a lot of extra coax which I try to
> avoid.
>
Nermin Bajramović
Could you please let me know the exact title of the book by Carr and its
ISBN number to try to purchase the book myself.
Also if you know where the book could be bought?
Thanks, season's greetings and Happy Y2K.
Nermin S58DX
Bob Sikes wrote in message ...
John - KI4RO
Your friend is correct....3/4 wavelength lines are usually what folks
use.
73
John
ARDUJENSKI
experience when I researched PAHSED VERITICALS.
Verticals and radial systems always result in losses. These could range from
20-80 percent depending on antenna length and radial system and ground
characteristics.
After much reading, I went with a portable INVERTED HALF SQUARE. This consisted
of two portable verticals that can operate on 40 and 20M primarily. (With a
tuner get 15 and 10M). I interconnect at the base of the antennas with the
proper 1/2 wave wire and feed at the bottom corner of one of the verticals.The
vertical antennas are made from telescoping 20ft fishing poles (like the St.
Louis Verticals). The vertical wire is cut for the low end of 20M and at the
base of the pole is a coil that when utilized tunes it for low end to 40M.Tfhe
fishing poles are mounted on portable tripods made from PVC putting the base of
the vertical about 6 ft above the ground.
The advantage is portability, ease in set up (5 minutes), can rotate for
desired direction of performance and relatively inexspensive.
Note that in general the difference between a vertical with 4 radials and one
with 120 radials is about 3 db (acording to handbook). The INVERTED HALF SQUARE
will give you about 3 db gain without all the radials and some directivity.
This has served me well for many cw sprints and contests. Alan KB7MBI
Gary V. Deutschmann, Sr.
I'll get flamed to death for this, but we ran co-phased ground planes
on the old 35 watt "BUSINESS PORTION" of the chicken band and it
outperformed a Mosely A-511S Beam to pick up our trucks working down
south because they were in scattered southern areas making the beam
almost useless.
In any case, when we connected the antenna's using 50ohm coax of 1/4
wavelength increments, it just didn't work right. We tried 1/2
wavelengths and still it was not right. We switched to 75 ohm coax
for the co-phasing sections, keeping both legs equal but at 1/4
wavelength multiples and pow, it was like somebody kicked in a
gigawatt footlocker in each of our trucks. The lead in was still 50
ohm coax not tuned around 150 feet give or take. But both of the legs
of the tuned section were identical lengths.
I never actually heard what the base signal sounded like at the mobile
end of the transmission since I was office bound, but the drivers
always came back to a call without fail. Almost, but not quite,
sounded as good as an FM repeater, hi hi....
TTUL
Gary
John P. Franklin
>
> I'll get flamed to death for this, but we ran co-phased ground planes
> on the old 35 watt "BUSINESS PORTION" of the chicken band
Why should you be flamed for that? What's wrong with class A citizens band?
Pat
W6RCecilA
> I interconnect at the base of the antennas with the
> proper 1/2 wave wire and feed at the bottom corner of one of the verticals.
How much loss is in that 1/2WL of wire 6 ft. off the ground?
--
73, Cecil, W6RCA http://www.mindspring.com/~w6rca
ARDUJENSKI
ground I had someone run some calculations on an antenna program and the loss
he reported was less than a 1/2 dB over running it at the top of the half
square. I have compared t in filed ops with a single vertical and it was night
and day difference Alan KB7MBI
Roy Lewallen
length, as long as they're equal. Some lengths will result in a better
match to 50 or 75 ohm coax at the common point, but changing the lengths
(as long as they're both equal) will make no difference to the radiation
pattern. This is also true of two elements fed out of phase, with the
difference that one feedline needs to be a half electrical wavelength
longer than the other.
This simplicity can't be extrapolated to a larger number of elements, or
to other phase angles, however. For more information about the general
case, see Chapter 8 of the _ARRL Antenna Book_, and "The Simplest Phased
Array Feed System -- That Works" in the _ARRL Antenna Compendium_, Vol.
2.
Roy Lewallen, W7EL
TRON
radiators.
Patterns on spacing and line length (electrical deg) can be found in the old
1986 ARRL Handbook, but i'm sure books like the Practical Antenna Handbook and
many others it also can be found.
I can't tell you how long of phasing line you need will be since it depends on
the desired, freq of op., desired pattern and spacing.
But here is the formula for Calculate Electrical Length Of A Line:
To calculate the electrical length of the line you need to multiply the
velocity factor of the line by the free space length. For the length in feet,
this is (983.6 / frequency in MHz) * velocity. For the length in meters, this
is (299.8 / frequency in MHz) * velocity.
The quarter wave transformer is one popular such use. Now you might think that
you would just take 300 / Frequency (Mhz) and divide by four to get a quarter
wave line. Don't do it! You'd be off. You see, radio waves travel slower
through different mediums. Which means the distance they can travel
(wavelength) for a full wave is less than in free space. The coax cable you are
using might for example, have a velocity factor of 66%. This indicates that the
electrical length is actually 66 percent of the free space length! Be sure to
figure this into your calculations.
Raw Power Radio
it very disappointing. I respect Carr and he's done a lot of good work
over the years, but this book is far from comprehensive and it
duplicates a fair amount of material from his other books. I consider
the ARRL Antenna Book to be a better resource.
* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
The fastest and easiest way to search and participate in Usenet - Free!
N4MXF
>it very disappointing.
I would agree. An excellent book for HF antenna work is John Devoldere,
ONRUN's "Low-Band DXing"--an ARRL Pub. Mainly focusing on 160-80-40meters
howeve,r all John's work applys to all HF band regions. A must book for serious
HF antenna builders. 73 Bill (K6EC)
Nermin Bajramović
Happy Millennium, first of all!
Yes I agree the Book by Joseph Carr is the book with simplistic and basic
antennas.
I have had already the book and I resell it. The book that I am looking for
is the book of Paul Carr N4PC or K4PC which recently run series of articles
in CQ-magazine. Also some excellent woks in articles in Lew Mc Coy book on
Antennas.
To repeat my question, does anybody knows what is the title of Paul Carr
N4PC
book and its isbn number.
Thanks Nermin S58DX
N4MXF wrote in message <19991230161507...@ng-fs1.aol.com>...
Gary O. Lyons
The book entitled "The Amateur Radio Vertical Antenna Handbook" was written
by Capt. Paul H. Lee, N6PL. The second edition (I wore out the first
edition) was published by CQ Publishing in 1984. The ISBN number is
0943016142. I just checked the Barnes and Noble web site and it appears the
book is a special order item.
This provides a good theoretical background of both single element verticals
and multi-element systems from a 50s-70s technology base. I agree with
Bill/K6EC, John Devoldere's book provides an excellent "practical" coverage
of verticals.
I hope you're able to acquire a copy.
73,
Gary W5ZL
Nermin Bajramović wrote in message ...
Nermin Bajramović
Mentioned book, Vertical antenna book by Paul Lee is in my library of
antenna books. The book I am looking for, is from Paul Carr N4PC or K4PC. He
has published a variety of articles in CQ magazine on doublets, loops etc..
Do you think that the Amazon.com might help me ?
Thanks anyway!
Best regards, Nermin S58DX
Roy Lewallen
book about antennas. I'm sure that if and when he does, it'll be good.
Roy Lewallen, W7EL
Lyle Koehler
Is it possible that the book in question is THE AMATEUR RADIO VERTICAL
ANTENNA HANDBOOK by Paul H. Lee, N6PL; ISBN 0-943016-14-2 ??
--
Lyle, K0LR
Nermin Bajramović
Thanks for the help. As you have said it will be great book, judging from
the published articles so far.
Happy Millennium Roy.
73's Nermin S58DX