|Nov 01, 2012, 07:23 AM|
Experiences with CP Antenna's bought off eBay?
Just wondering if any of you have any experiences good or bad with Circularly Polarised Antenna's bought off eBay. I bought myself a pair for 5.8Ghz for $40 from eBay just now and was wondering what to expect.
|Nov 02, 2012, 09:15 AM|
When buying these off of Ebay or searching for a bargain in general, be very careful to look at construction technique. You should be looking for a few things:
1. Sustainability of the build - Look for one that has strong solder joints. Solder to steel wire is weaker than soldering to copper. Many use pin point soldering that breaks very easily namely at the base.
2. Feedgap - A large feed gap throws off resonance, weaken the antenna, and shows lack of care for proper construction.
3. Round corners - Sharp corners cause spurious emissions and it also harms circularity.
4. Balancing - Look for antennas that have a balun at the base or ones that have consistent length. Stray currents due to skin effect run down the outside of the cable causing it to act like a dipole and harm the antenna's circularity.
5. Wire size - Many use thicker wire than what the antenna calls for which puts the antenna out of resonance.
When looking for a bargain, be sure to find one as the antenna is the critical link between your airplane and the ground. Generally you get what you pay for.
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