How High to Put Satellite Antenna

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wyShack

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Ok, I have been modeling a couple of antennas to 'work' the 'Easysats' (FM repeater types'). Can anyone share their experiences? My modeling with EZNEC shows a better pattern if I keep the antenna closer to the ground. If I get it up over my roof, the model shows some serious nulls in the pattern. If I install the antenna lower,will my wooden house 'block' the signal? If not, I can get a better pattern and shorter coax runs.

Up over my house at about 15 feet I am hearing the satellites (even the beacons on the SSB birds), but the signal fades in and out as the signallevelis right on the bottom of my TS2000's ability to hear.

Hoping to get both 70 CM and 2 meter antennas up (either turnstiles or Moxoms) so I can operate satellite from my shack.

Any suggestions?
 

wd9ewk

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Ok, I have been modeling a couple of antennas to 'work' the 'Easysats' (FM repeater types'). Can anyone share their experiences? My modeling with EZNEC shows a better pattern if I keep the antenna closer to the ground. If I get it up over my roof, the model shows some serious nulls in the pattern. If I install the antenna lower,will my wooden house 'block' the signal? If not, I can get a better pattern and shorter coax runs.

Up over my house at about 15 feet I am hearing the satellites (even the beacons on the SSB birds), but the signal fades in and out as the signallevelis right on the bottom of my TS2000's ability to hear.

Hoping to get both 70 CM and 2 meter antennas up (either turnstiles or Moxoms) so I can operate satellite from my shack.

Any suggestions?

Directional antennas would do better than omnidirectional antennas. If you are limited to omnidirectional antennas, what you may be seeing is the roof of your house acting like a ground plane for your antenna. Preamps may be needed to improve performance of those antennas, along with a careful view of the coax used between the antennas and your radio.

You don't necessarily need to put those antennas high in the sky, unless you have trees, other houses, etc. near your location that prevent the use of lower antennas. We're not talking about HF antennas, where antenna height can be more important.

Good luck!
 

ab5r

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Visibility of the satellite is ONE of the key factors. If, as previously mentioned., you do not have trees, mountains, houses and etc. restricting the view; you can operate from the ground. Also, below a certain elevation will cause intermittent and weak signals. Therefore, horizon to horizon reception is only for those that can afford optimal antennas, preamps and feed lines.

You probably can go to WWW.AMSAT.ORG and get more information. JOIN, if you can.

Remember too, simply adding a preamp ALSO amplifies noise as well as signal. Without proper filtering inline, you may not have optimal reception. Occasional dropouts are normal as the bird tumbles and spins for some birds.

Good luck.
 

wyShack

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I guess my real question is how much would my 'stick built' home affect the signal? If I roof mount the antenna , it looks like I will get some 'nulls' in the pattern. Lower down,the pattern is smoother(and I would have a shorter coax run). The question is, does the house itself more loss that the coax gain? While I can use a handheld to hit the local repeater from inside the house, hearing the satellites doesn't have near as much margin. Don't want to install them down low and then find I can't hear whole passes that are shaded by the house.

Thanks for the comments
 

ab5r

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"I guess my real question is how much would my 'stick built' home affect the signal?"

If this the same antenna that you are comparing "on the ground" and "on the roof"; I don't see why the SAME antenna would affect reception, unless the ground is acting as a ground plane. What type antenna are you using: omnidirectional, yagi, or what?
 

wyShack

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When I model the antenna (a turnstile type I built) using EZNEC, the 'gain' varies by about 5 dB from an elevation of 8 to 90 degrees (straight up). If I model it at 15 feet, the gain at 14 degrees is like 12 db down and there are other dips but that is the worse. I am trying to use a stationary antenna so I can work more of the pass and don't have the resources for AZ/EL rotors.

Trying to use the antenna on the roof, I am operating right at the 'floor' for my setup so when a satellite goes into one of the 'nulls' I 'lose' it. Just wondering if the house would knock the signal down as bad..
 

wd9ewk

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When I model the antenna (a turnstile type I built) using EZNEC, the 'gain' varies by about 5 dB from an elevation of 8 to 90 degrees (straight up). If I model it at 15 feet, the gain at 14 degrees is like 12 db down and there are other dips but that is the worse. I am trying to use a stationary antenna so I can work more of the pass and don't have the resources for AZ/EL rotors.

You could use a Yagi or log periodic, pointing up 15 to 20 degrees above your horizon or surroundings, mounted on a TV antenna (or any azimuth-only) rotator. You might miss the very few passes that go directly over your head, but you'll do better on most other passes. Antennas similar to the Arrow dual-band Yagi or Elk dual-band log periodic can be used in this way. You don't need long-boom Yagis for the current amateur satellites.

http://arrowantennas.com/arrowii/146-437.html
https://elkantennas.com/product/dual-band-2m440l5-log-periodic-antenna/
http://wa5vjb.com/references/Cheap Antennas-LEOs.pdf

For the most part, amateur satellites aren't heard well with most omnidirectional antennas. Preamps, along with better coax, are normally needed to make up for the lack of gain in the omnidirectional antennas.
 

db_gain

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As long as the antenna is exposed to the birds with an unobstructed path, you should be golden.
 
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