When I used to do a lot of driving for work I used to use a 1/4 wave, and a high gain vertical antenna to work the birds. I would switch between the high gain when the bird was coming up to the 1/4 wave when it was up 15 degrees or so. Then back to the high gain vertical when it was getting back down below 15 degrees or so. Another good trick was to use the 1/4 for TX only, and listen with 1/2 of an Arrow (with pre-amp) for the 70cm, D/L out the drivers window, this would give you near armchair copy, when pulled over of course !
73 Jeff kb2m -----Original Message----- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Bob Bruninga Sent: Saturday, May 30, 2009 8:19 AM To: mikehooles; amsat-bb@amsat.org Subject: [amsat-bb] Re: Re eggbeater performance - mobile > For mobile work on AO27, SO50, AO51 > a 2 metre quarter wave whip is all > you need... to work the LEO's mobile > and the satellite is 15 degrees or > more above the horizon, Absolutely, For a 19.5" whip in center of roof: 1) Has 5 dBi gain above 20 deg on 2m 2) Has 7+ dBi gain above 30 deg on 70cm 3) Is an omni 4) does not sacrifice 3 dB for circular 5) Above 25 deg, satellite is 6 to 10 dB closer! 6) works the birds solid for the center of high passes 7) Simplicity at its best! Read about it: www.aprs.org/rotator1.html Disadvantage: The only disadvantage is TIME. On the above web page you can also see that satellites spend 70% of their daily pass times below 25 degrees. BUT! For those best passes in the morning and the evening (or whenever) you can make solid contacts while mobile for about 5 minutes. Also note, that you do NOT need any tracking program to predict passes. AO51 schdule repeats evry 5 days for example. Just write down the CENTER pass of the morning and evening for each day for 5 days. Update those 10 times on a small 3/5" card on the dash about once a month or so will predict all passes whenever you are mobile. There will be a pass 100 minutes earlier and 100 minutes later each day too. So you can predict all 6 passes a day from those same 10 times. See how: www.aprs.org/MobileLEOtracking.html Bob, WB4APR _______________________________________________ Sent via amsat...@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
