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Old Feb 23, 2012, 11:11 AM
windfou is offline
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Joined Dec 2008
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Quote:
Originally Posted by markus123456 View Post
Ok, these are not "my" $60 antennas I'm not Alex. I charge $20 per antenna. So much about that.

These antennas should be used with a coax extension cable. If you mount them as is, the nearby rx or tx will violate the near field of the antenna, changeing it's radiation pattern significantly.

Wether they work well or not also depends on many factors. As a matter of fact, CP antennas on 5.8G - provided the individual antenna is not defective and well built and tuned - outperform linear antennas easily. However, if an antenna is not well built, bent, defective or mistuned, performance might be very poor. Those antennas, based on the wire thickness are obviousely delicate and one must take care not to bend them. You should asume that antennas you get fullfil the other requirements (well built, no dents, tuned). If not, this is IMHO a waranty kind of situation. I can only speak for myself but I figure Alex and Hugo also take their work seriousely. If one of my customers gets a not well performing antenna, he will get a free replacement. If the plane crashes and the antenna gets dented (or get's dented while handling it) one can send me the antenna for repair at the cost of the return shipping fee provided the antenna is not totally smashed.

I suggest you contact either redymaderc or Alex about that.

Regarding the general performance of CP antennas over linear ones I can say that CP antennas have two significant advantages. Advantage number one is that they almost totally cancel out reflections. Reflections are very very common the higher the frequency is. In fact, frequencies around 5Ghz and up are often used for radar applications because they DO reflect so well. Every reflection of the signal that arrives at the receiver antenna will cause an interfrenence in the receiver leading to a disorted signal / picture. Advantage nuber two is that CP antennas almost do not depend on the positioning of the receiver and transmitter antennas compared to each other. Linear antennas HAVE to be alligned for best performance. If they are "crossed up" (in a 90 degrees angle to each other), you loose 12dB and in layman terms, that's more than 100 times less of the signal. Not so with CP antennas.

Other than this, linear antennas as well as CP antennas have to radiate (in case of the tx antenna) and receive the signal. Both do that equaly well. What I'm trying to say is that there are no "wonder antennas". There are antennas which are well adapted to a specific problem (like CP antennas for FPV where the plane banks and where we have reflections due to the frequencies used) and some which are not so well adapted (linear antennas are not good with banking and reflections). If we compare these antenna types, we must assume that such comparison is made with tuned antennas such that each antenna has a chance to truly radiate or receive. If this is not given (like it seems to be the case with the antennas you have) such a comparison is pointless.

Markus
ok so depend the side i turn the aicraft i can lose lot of signal with my linear stock antenna but the cp antenna the patern is diferent and you lose less signal and not need to turn my head to reach the siganl ok thanks i want a set from you please pm me
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