[amsat-bb] Re: DX LEO records, fixed elevation category

Bruce Robertson broberts at mta.ca
Fri Mar 9 05:36:22 PST 2007

Quoting Anthony Monteiro <aa2tx at comcast.net>:

> At 11:07 PM 3/8/2007, Bruce Robertson wrote:
> >Many of us have been encouraging the newcomers to this list to avoid
> >elevation rotors if they want to begin with a simple, less expensive
> >station. (It is unfortunate that as recently as my 2006 edition, the
> >Handbook states that az/el rotation is necessary. I wonder if someone
> >should contact them and offer a rewrite.) As evidence of the
> effectiveness
> >of such a station, I offer the following two QSOs (chosen merely
> because I
> >was writing up the QSL cards). I also submit them as the first entries
> in a
> >fixed-elevation DX bragging thread:
> >
> >VE9QRP (FN75tv) to IW4DVZ (JN54IM) 5600 km
> >"             " to OK2UFB (JN99as) 5847 km
> Dear friends,
> I agree with Bruce, you do not need fancy antennas
> to work DX on LEO satellites. Here are a few I found in my log
> that were completed using just omni-directional antennas
> - NO rotors at all:
> AA2TX (FN20) to:
>          PA0TAU (JO22) 5987 Km
>          SM6DJE (JO99) 6411 Km
>          OM3MM  (KN09) 7084 Km
> The distances were calculated using:
> http://home.arcor.de/waldemar.kebsch/The_Makrothen_Contest/fmaidenhead.html
> Best DX and 73,
> Tony AA2TX

Sadly, the International Panel of Judges (my cats, Oreo and Starry) has
determined that omni-directional antennas belong in a separate category,
thereby preserving VE9QRP's fixed-elevation directional antenna records for
another 3h :-)

On a more technical note, Tony are these with your Lindenblads described in
the latest Symposium proceedings? I'm a bit confused about the performance
of omni-directional circular polarized antennas. I have been told that LEO
satellites tend to switch from RHCP to LHCP as they change their
orientation and that, therefore, it is best to include polarity switching
in a CP yagi. Does this same phenomenon cause deep fades in an antenna like
the Lindenblads, despite the ideal radiation (reception) pattern? Also, how
does one deal with the 2m LHCP/RHCP kerfuffle in, for example VO-52
downlink and FO-29 uplink? 

(I'm using this helpful list as my data:

Finally, does anyone have a more recent ARRL Handbook? If so, can you check
if it persists in suggesting that an az/el rotor is an important asset for
fixed-station, LEO satellite work? If it does we should seek to have it
replaced with material based on more recent articles in QST that contradict
this. I'm sure I'm not the only one who browses through the handbook to see
what assets I have for undertaking new modes: if people knew it was just a
matter of putting two short beams on one boom and tilting them up 20 deg.,
they might be more likely to give it a go.

Bruce Robertson, 
Dept. of Classics, Mount Allison University

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