Re: Commercial Mode L Antenna sources
I'm surprised how few people have mentioned parabolic dishes during this discussion about commercial Mode L antennas. L-band uplinks are mostly used in combination with a S-band downlink. Most people build L/S equipment with HEO satellites in mind. A single yagi or helix doesn't usually provide sufficient gain for L/S band use with a HEO satellite. You need the gain of a dish for satisfactory S-band reception of a HEO satellite. So one practical solution is an oversized dish with a L/S dual-band feed (helix or patch). A 4-foot dish was proven to work well for this on AO40. In my opinion a single 4-foot dish is more practical than, for example, cobbling together multiple yagi/helix antennas for S-band downlink and multiple yagi/helix antennas for L-band uplink.
My 4-foot dish and dual-band patch feed were purchased commercially from Teksharp (Rick Fletcher KG6IAL). http://www.plumdragon.com/teksharp/hr_AO-40_products.htm The dual-band patch feed is sold fully assembled and tested, but the dish was a kit. I had to locally purchase 1/4 inch hardware cloth, cut it into 8 "petals", and use 200 zip ties to attach the petals to the frame of the dish. A mesh dish has somewhat less wind loading than a solid dish. That's important because a solid 4-foot dish has a maximum wind load of more than 12 square feet, exceeding the wind load rating of my G-5500 rotor. A picture of my satellite antennas can be seen here: http://s238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/
Wayne Estes W9AE Oakland, Oregon, USA, CN83ik
Wimo got some use in the old days as well.
http://www.ssbusa.com/wimohelix.html
I have a 23-2 which was okay (not great) with AO-40 with 10 Watts until the AGC started getting pumped. It is too much for AO-51, so I reduce the power.
73, Joe
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Wayne Estes Sent: Wednesday, July 02, 2008 12:34 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: Commercial Mode L Antenna sources
I'm surprised how few people have mentioned parabolic dishes during this discussion about commercial Mode L antennas. L-band uplinks are mostly used in combination with a S-band downlink. Most people build L/S equipment with HEO satellites in mind. A single yagi or helix doesn't usually provide sufficient gain for L/S band use with a HEO satellite. You need the gain of a dish for satisfactory S-band reception of a HEO satellite. So one practical solution is an oversized dish with a L/S dual-band feed (helix or patch). A 4-foot dish was proven to work well for this on AO40. In my opinion a single 4-foot dish is more practical than, for example, cobbling together multiple yagi/helix antennas for S-band downlink and multiple yagi/helix antennas for L-band uplink.
My 4-foot dish and dual-band patch feed were purchased commercially from Teksharp (Rick Fletcher KG6IAL). http://www.plumdragon.com/teksharp/hr_AO-40_products.htm The dual-band patch feed is sold fully assembled and tested, but the dish was a kit. I had to locally purchase 1/4 inch hardware cloth, cut it into 8 "petals", and use 200 zip ties to attach the petals to the frame of the dish. A mesh dish has somewhat less wind loading than a solid dish. That's important because a solid 4-foot dish has a maximum wind load of more than 12 square feet, exceeding the wind load rating of my G-5500 rotor. A picture of my satellite antennas can be seen here: http://s238.photobucket.com/albums/ff239/Wayne_Estes/Ham%20Radio/
Wayne Estes W9AE Oakland, Oregon, USA, CN83ik _______________________________________________ Sent via AMSAT-BB@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
participants (2)
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Gary "Joe" Mayfield -
Wayne Estes