Using Arrow Antennas
I’ve made phasing lines for two Arrow antennas. I decided to use my RigExpert to first check SWR on the antennas and found some surprising results. At 435 mhz, which is close to where much of the satellite activity is, I’m seeing 3:1, at 437 mhz it’s 2.4:1 and it’s best reading of 1.3:1 is at 440 mhz.
I’ve successfully used a single Arrow from my summer QTH for years and it’s measurements are much better than this brand new 2nd Arrow.
I’ve tried adjusting the match and that seems to make no real improvement in terms of lowering the resonant frequency on 70cm.
There doesn’t seem to be such a problem on the 2 m side.
I really need to get both antennas to have a reasonable and similar SWR readings at 436 mhz before introducing the phasing lines and so far I’m having real trouble making that happen. Any suggestions will be appreciated. And yes I’ve checked to make sure I built the antenna properly with all of the elements in the right places.
Rick, W2JAZ
The arrow was never a great antenna. Antenna guru Kent Britain once said something to the effect the Arrow was designed to have the elements insulated from the boom, but they are not. There is plenty room for improvement, but it is such a handy design from a mechanical view and it does what we need…
There was talk of an ‘improved Arrow’ but it never appeared. I had hoped when Arrow bought Gulf Alpha they would run with one of those designs, but no such luck.
I still regret parting with my Gulf Alpha, man that was a good antenna, both mechanically and in terms of performance.
If someone decides to run with an ‘Improved Arrow’ or resurrects the Gulf Alpha, count me in.
73, Joe kk0sd
From: Richard Lawn rjlawn@gmail.com Sent: Sunday, July 25, 2021 9:20 PM To: amsat-bb@amsat.org Subject: [AMSAT-BB] Using Arrow Antennas
I’ve made phasing lines for two Arrow antennas. I decided to use my RigExpert to first check SWR on the antennas and found some surprising results. At 435 mhz, which is close to where much of the satellite activity is, I’m seeing 3:1, at 437 mhz it’s 2.4:1 and it’s best reading of 1.3:1 is at 440 mhz.
I’ve successfully used a single Arrow from my summer QTH for years and it’s measurements are much better than this brand new 2nd Arrow.
I’ve tried adjusting the match and that seems to make no real improvement in terms of lowering the resonant frequency on 70cm.
There doesn’t seem to be such a problem on the 2 m side.
I really need to get both antennas to have a reasonable and similar SWR readings at 436 mhz before introducing the phasing lines and so far I’m having real trouble making that happen. Any suggestions will be appreciated. And yes I’ve checked to make sure I built the antenna properly with all of the elements in the right places.
Rick, W2JAZ -- Sent from Gmail Mobile
Hello. I have an arrow that I built with "target shooting arrows" I practically used the same measurements of the original arrow and I built a band pass diplexer with which I could adjust the SWR by opening and closing the loops.
In the same way, moving the gamma match a little as necessary, I have 1: 2 in VHF and 1: 4 in UHF, it must be taken into consideration that depending on the position of the antenna the SWR varies, or at least that is what I could express.
https://www.instructables.com/Antena-Para-Sat%C3%A9lites-LEO-Radioaficionado...
Ignacio - TI3IES
El dom, 25 jul 2021 a las 20:21, Richard Lawn (rjlawn@gmail.com) escribió:
I’ve made phasing lines for two Arrow antennas. I decided to use my RigExpert to first check SWR on the antennas and found some surprising results. At 435 mhz, which is close to where much of the satellite activity is, I’m seeing 3:1, at 437 mhz it’s 2.4:1 and it’s best reading of 1.3:1 is at 440 mhz.
I’ve successfully used a single Arrow from my summer QTH for years and it’s measurements are much better than this brand new 2nd Arrow.
I’ve tried adjusting the match and that seems to make no real improvement in terms of lowering the resonant frequency on 70cm.
There doesn’t seem to be such a problem on the 2 m side.
I really need to get both antennas to have a reasonable and similar SWR readings at 436 mhz before introducing the phasing lines and so far I’m having real trouble making that happen. Any suggestions will be appreciated. And yes I’ve checked to make sure I built the antenna properly with all of the elements in the right places.
Rick, W2JAZ
Sent from Gmail Mobile
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i was under the impression that the driven element length effects the resonant frequency, and the gamma match is there for impedance matching, 50ohms.
here is an internet quote from http://www.dx-antennas.com/Gamma_match.htm "The Gamma match is the most used matching device used for yagi beams. ... A well designed yagi has for that reson an impedance around 20.. 25 ohms. A Gamma-match can match impedance below 50 ohms right up to that 50 ohms wich your tranceiver wants to see." (spellling errors are left for your enjoyment)
i would think you may need longer elements on the driven element to lower the freq. a bit. are they the same length as the older arrow antenna that you have? you can probably get an extra set of driven elements, or the whole thing with match, from arrow? or get a set of the reflectors and trim them down.
or just get some arrows, mine says "Easton JAZZ 1816 lite" on the elements https://www.eders.com/easton-xx75-Jazz-arrows-1816-spine.html?gclid=Cj0KCQjw...
73 K F o G cm88pk santa rosa, ca, usa
Hi Richard,
Make doubly sure the element you have installed opposite the driven element is the correct matching element, i.e., exactly the same length. They are all close to the same length and it's easy to get them confused. It sounds like, if it's not the correct element, you have one that's a little too short. Worth checking again...
73,
Ken VE3HLS
I used a labeler to number all my element sets for both bands. Makes it a lot easier to set up because I don’t have to repeatedly ppmeasure things to get the right sizes for each position. One through seven for the 70 cm side one through three for the 2 m side, 10 and four if using the Alaskan version. It helps so much.
Sent from my iPhone
On Jul 26, 2021, at 22:43, ve3hls@gmail.com wrote:
Hi Richard,
Make doubly sure the element you have installed opposite the driven element is the correct matching element, i.e., exactly the same length. They are all close to the same length and it's easy to get them confused. It sounds like, if it's not the correct element, you have one that's a little too short. Worth checking again...
73,
Ken VE3HLS
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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I did essentially the same thing with different colored tape. -David, N9KT
On Tue, Jul 27, 2021 at 4:49 PM Tom Schuessler via AMSAT-BB < amsat-bb@amsat.org> wrote:
I used a labeler to number all my element sets for both bands. Makes it a lot easier to set up because I don’t have to repeatedly ppmeasure things to get the right sizes for each position. One through seven for the 70 cm side one through three for the 2 m side, 10 and four if using the Alaskan version. It helps so much.
Sent from my iPhone
On Jul 26, 2021, at 22:43, ve3hls@gmail.com wrote:
Hi Richard,
Make doubly sure the element you have installed opposite the driven
element is the correct matching element, i.e., exactly the same length. They are all close to the same length and it's easy to get them confused. It sounds like, if it's not the correct element, you have one that's a little too short. Worth checking again...
73,
Ken VE3HLS
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
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Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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participants (7)
-
David Spoelstra -
Gary -
Ignacio Granados Vega -
Richard Lawn -
robertinorbit＠webtv.net -
Tom Schuessler -
ve3hls＠gmail.com