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Are Base loaded Receiver Antennas OK for fixed Wing??

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Old 01-06-2005, 08:56 AM
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Meesh
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Default Are Base loaded Receiver Antennas OK for fixed Wing??

I know the Heli guys use these antennas quite regularly (small whips that require you to cut your receiver antenna to 4" then solder the whip lead to the 4" stub) but has anyone used these on fixed wing aircraft that typically fly at greater distances from the pilot than helicopters??

They look much better than antenna wires.
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Old 01-06-2005, 09:02 AM
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LSP972
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

I have used them on and off in fixed wing models for years; usually because it was a former helicopter receiver that I hadn't gotten round to replacing the whip with the standard one meter wire antenna.

My trainer has a Dean's in it right now, and that airplane sees quite a bit of use working with newbies.

IOW, they will work fine in airplanes. Just be sure to keep it as far away from other electronics as possible. You should do that with ANY antenna.
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Old 01-06-2005, 11:30 AM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

Thanks Steve!

Bob
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Old 01-07-2005, 12:53 AM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

Another question relating to this. I don't know how true it is, but isn't an antenna's length determined by the frequencies it is set to recieve? I heard that about car radios, that they have to pick a length that falls between the am frequencies, and fm frequencies for optimal reception. If this is true, wouldn't shortening the antenna reduce it's ability to pick up the frequency it was initially intended to, despite the fact that there may be something boosting the signal? Another example of this is if you look at a surface (27 mhz?)recievers antenna, it is somewhat shorter than an airborne receivers antenna. I'd really like to use a base loaded antenna on my plane, but I don't like the thought of what I described, even though so many people have not had problems with them.
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Old 01-07-2005, 07:20 AM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

The way I understand "Base Loaded" means that there is a coil or something in the base of the antenna that mimmicks the standard length antenna.
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Old 01-07-2005, 08:02 AM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

You could think of a base loaded antenna as a standard length with most of its length wound up in that tight coil at the base. An over-simplification, but I've not been involved in RF theory for many years, so don't want to confuse myself and others about the fine points.
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Old 01-07-2005, 01:19 PM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

Well here's where it can get tricky. Since radio waves are similar to ocean waves, being that they rise and fall, it seems really stupid for the antenna to be shorter than the wave itself, causing some to spill over the antenna effectively reducing it's ability to pick up the signal. also, isn't it true that with FM radios, the frequency is varied slightly with the change of control inputs, cause doesn''t FM stand for frequency modulation? I'm not trying to be an ass about this. I'm gonna get myself one of the antennas, but it just got me thinking about how effective they are.
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Old 01-07-2005, 01:44 PM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

Okay, I'll take a shot at explaining this, but it's been a while, so bear with me. When I was heavily involved in amateur radio in past years, I preferred 10 meters. This means that the wavelength was 10 meters, or about 33 feet. Now, it's not too practical to try and have an antenna on a car that is 10 meters long, so we used a base loaded antenna. Electrically, the antenna is 10 meters, or a reasonable fraction like a quarter wave, half wave or something like that, but in actual measurements, it's only about 3 feet or less in length. For receiving, the length of the antenna becomes less critical, and for transmitting, it's more critical as the radiated power gets higher. With the amount of power we're transmitting with our radios, close is more than good enough! The range you should get out of a properly set up system will be more than you are able to see the plane well enough to control it. The exception comes in with some of the larger planes, but by that time, you're likely to be able to control the plane well enough to keep it where you want it. A base loaded antenna will NOT have the range of the full length antenna that comes with the receiver, BUT, it will have more than sufficient for most uses. The biggest things that limit range are installation problems and crash damage to equipment.

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Jim
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Old 01-07-2005, 01:49 PM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

Thanks Jim. That is what I thought. I'll asume that with a good clean installation and a good range check they would be fine for normal sport flying.

Bob
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Old 01-07-2005, 01:55 PM
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Default RE: Are Base loaded Receiver Antennas OK for fixed Wing??

Thats the kind of explanation I was looking for. Thank you too
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