[Moon-Net] 2M antenna matching Data

Ingolf, SM6FHZ ingolf.fhz at gmail.com
Tue Nov 8 21:27:56 CET 2016


Hi all.

I made a simulation on how the radiation patterns of a yagi array actually
are affected with phasing errors. It is not that dramatic. I used a
four-stack of 432 MHz 9 el yagis in a box configuration as an example (the
antenna I have at the city QTH for tropo and aurora).

The beam will squint somewhat and the side lobes will become unsymmetrical.
The first step I used was an phase error of 20 degrees. A few degrees of
squint and a few dB of unsummetrical sidelobes. With 45 degrees of phase
error the effect is more pronounced. No big loss in directivity of the
array.

You find the presentation here:
http://2ingandlin.se/Phase%20errors%20in%20stacked%20yagis.pdf

You can also find it this way:  http://2ingandlin.se/engineering.htm

I hope it will be to some help in this mail thread.

73 es gl

Ingolf, SM6FHZ



2016-11-08 18:56 GMT+01:00 Conrad PA5Y <g0ruz at g0ruz.com>:

> Here is a tip for cutting phasing lines with adequate accuracy for 2m.
>
> Presumably we all have a long piece of metal tubing.
>
> In my case I wanted lines of 4m long so I put the N type on one end of the
> cable and slid a washer over the cable so that the connector could not go
> into the 4m long piece of tubing that I had. Put the coax into the tubing,
> pull the cable tight so that the connector is right up against the washer
> and the washer is up against the end of the tube. With the cable under
> tension cut the cable at the opposite end of the cable. Be careful that you
> fit the connectors using the same dimensions after you have cut and you
> will be within a few degrees at 2m. I did 8 cables this way and the total
> spread measured on an R&S VNA was 2.6 degrees.
>
> More than good enough.
>
> Regards
> Conrad PA5Y
>
> On 8 November 2016 01:42:53 CET, Ray Rector <wa4njp at bellsouth.net> wrote:
>>
>> Well said Serge, same roll close together make them the same length and
>> put it on the air... Yes there will be some difference, but you or I and
>> the people you are working will not know the difference,  Spend all day,
>> make them with in 0.00001 wavelength of the same, and you will not realize
>> the difference, you nor I have the ability to see of check any difference..
>> We all would like it to be perfect, we can get very close with a tape
>> measure, on 144 or below you probably will never see the difference..
>> Ray
>>
>> ------------------------------
>> *From:* serge <ve1kg at eastlink.ca>
>> *To:* Steve Bell <eagle572 at comcast.net>; moon-net at mailman.pe1itr.com
>> *Sent:* Monday, November 7, 2016 5:09 PM
>> *Subject:* Re: [Moon-Net] 2M antenna matching Data
>> GE Steve
>> Just cut 2 equal lengths of coax from the same roll of coax if possible
>> then
>> you are done.
>> Serge VE1KG
>> ----- Original Message -----
>> From: "Steve Bell" <eagle572 at comcast.net>
>> To: <moon-net at mailman.pe1itr.com>
>> Sent: Monday, November 07, 2016 8:18 PM
>> Subject: Re: [Moon-Net] 2M antenna matching Data
>>
>>
>> > Curt,
>> >
>> > I have the same question---I have a 13 El 2m Yagi per K1FO design and
>> > wish to build a second one, with added phasing harness to improve my EME
>> > capability.
>> >
>> > It looks like the different phase angles which you measured may cause
>> > trouble with the total array gain and also affect the antenna pattern.
>> >
>> > ! Please keep this topic on Moon-net for others to ponder.
>> >
>> > Steve Bell KJ7OG
>> > _______________________________________________
>> > Moon-Net posting and subscription instructions are at
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>> >
>>
>> _______________________________________________
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>>
>>
>> ------------------------------
>>
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-- 
Ingolf, SM6FHZ
http://www.2ingandlin.se/SM6FHZ.htm
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