On Fri, Mar 28, 2008 at 7:55 PM, Alberto Mart [email protected] wrote:
I do belong a TS-2000k and i'd experience some traffic over satellite. I did attempt using my vertical but results did not make me happy (very limited, in time, footprint and fading). I was recommended to check Gulf Antenna but they have jsu drop satellite's solutions (in term of antennas).
I would buy a pair of 2 mts and 70 cms antenna and phasing them. Where could I find more infos ? i did "google" as well but did not find usefull infos (from my point of needs).
I do hope some "guru" here could forward me to the right antenna's manufacturer.
73s de Alberto, iz0fma
Alberto:
I'm by no means a guru, but I'm happy I followed the advice of the gurus who recommended me to build my own antennas for LEO communications. In truth, the LEOs do not require very high-gain antenna systems.
One approach which has please many of us is to use a simple TV-type rotor to rotate two yagis which are pointed at an elevation somewhat above horizontal, say around 20 deg. If you keep the gain of the yagis low, you can adjust the rotor manually a couple of times during a pass.
I have built four antennas using the Kent Britain 'Cheap Yagis' design in single polarization. I used bronze welding rods, not aluminum, as elements. My 435 MHz antenna is an 8 element design, and the 144 was three. I'd be inclined to go for 4 elements on 144, but with that combo you can work all the LEOs with great style. I built these without an antenna analyzer, using a VHF/UHF SWR meter. You don't need to get the SWR perfect for satellite work.
Please note, though, that there is pretty broad consensus that for any antenna design you should have a mast-mounted low noise preamp installed, especially on 435 MHz. In my experience everyone's advice is based on the assumption that you have one of those. In your case, with the 100 and 50w available on transmit, the uplink power will never be a problem with working receiving antennas.
I'm slowly upgrading all this to a full az-el arrangement with higher gain antennas. This is a considerably greater engineering challenge, and means that, in the Winter, if anything goes wrong I'm off the air for quite a while. I'm enjoying trying to meet the challenge, but my struggles make me all the more certain that a simple, low gain, design is ideal.
73, Bruce VE9QRP