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Re: Arrow antenna



HI Jim

Sorry for delay in replying... been a tad busy over the past 48 hours.

The spacing is 6'. There's no particular reason for this, and I've read
many, many different suggestions for this. I went from a recommendation of 1
wavelength at 2m, from the Satellite Handbook.

Quite how important the spacing is is up for discussion, and I'm certainly
not an expert. I do, however have the benefit of empirical results, where I
can work all sats, digital and analog, with 100% reliablility every pass
except AO-10 where it has to be <15,000km. This is, of course, assuming the
sat is switched on!!

I can assure you that the difference between using the approach on my web
page (www.btinternet.com/~hlong) with 2 Arrows is a _massive_ improvement
over omnis!!

I have tried to place all elements for each band on one boom, but I had
enormous difficulties in tuning in. In fact I failed! If someone manages
this successfully I'd be very interested.

A problem in using separated antennas is that of squint angle. I find that I
regularly have to switch polarization during a pass maybe three or four
times on a LEO, and also the 3db point on the antenna lobes are much sharper
because of the squint angles, especially on 70cm. And you get a number of
side lobes too! You also need to keep your rotor tracking fairly regularly.

I usually don't need to bother switching the 2m polarization during a pass.
AO-40 comes in S5 almost horizon to horizon RHCP. The first/last two or
three degrees sometimes seem to appreciate some TLC, switching between RHCP
and LHCP.

You can of course simplify by fixing polarization, and you will certainly
have more success than with an omni. RHCP is the preferred option in this
case.

A year ago I still thought I needed long yagis for satisfactory enjoyable
Sat QSOs. I have satisfied myself that this is incorrect!

73 Howard G6LVB

----- Original Message -----
From: "Jim Cordill" <jcordill@worldnet.att.net>
To: <howard@howardlong.com>
Sent: Friday, December 01, 2000 1:13 AM
Subject: Arrow antenna


> Hi Howard,
>  I saw your Arrow antenna setup and I am in the process of doing
> the same thing, I have on question, it the spacing between the two
> Arrow antenna critical?  How far apart do you have yours?  Ok, one
> more question, how offen do you find you have to switch polarity
> on your setup.  Could I simplify my setup to just feed the antenna's
> one way, at least to start, and find it works most of the time?
> Which way seems to work best, Horz, Vert, RHCP, or LHCP?
> Cheers & 73,
> Jim KI0BK
>
> PS. thanks for the web site, lots of good info!
>
>

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