Peter Hackett <[email protected]> writes: > Can I just bend the whip antenna into a horse-shoe shape to get it to fit > into the altimeter bay? (I guess the really question is "Will this > significantly compromise the performance of the antenna?") And if it > is "a bad idea" what should I do?
It's a bad idea for two reasons. One is that it'll dramatically impact the radiation pattern, as you surmise. The second is that doing that will put strain on the SMA connector's attachment to the board, which isn't a good idea. I've had to repair boards that had the SMA damaged or sheared off because of loads put on the connector by such an antenna setup... sadly, one was one of my own boards that I stuffed in a 54mm airframe in a hurry at a launch a couple of years ago .. /o\ > My first thought was to find a short SMA male to SMA female cable so that > the whip antenna can be straight. Is this "a good idea"? (necessary?, > etc) That's a better plan. > Next: in poking around the Altus Metrum and gag.com web sites while > researching about my altimeter question, I saw a link to a "SMA To BNC > adapter" on the Teledongle page. > > I bought an Arrow II Hand Held Portable Antenna 440-3 and in looking more > closely at the product description page, it looks like it has a BNC > connector. > > So it looks like I'll need to get either the SMA to BNC adapter or get a > coax cable with a male SMA connector on one end and a male BNC > connector on the other. Have I got that right? Yes. > If so, any recommendations? Ok. The SMA-BNC adapter is the optimal way to attach a TeleDongle to an Arrow antenna. It puts the receiver as close to the antenna feed point as possible, which minimizes the loss between the antenna and the receiver, giving you the best possible system noise temperature. On the rocket end, I really prefer the wire whip. The only reason to use an SMA is if you're installing the board in something like an aluminum or carbon fiber airframe section (both are more or less opaque to RF signals) where you need to remote mount the antenna(s). Given that you have the SMA connector on the board, the two most plausible choices are to use a short SMA male to female cable to remote the whip, or to make up a simple wire whip with an SMA on it to use as an antenna. > Peter "I just got my ham radio technical license, so *clearly* I'm an > expert on all things RF" Hackett ;-) No worries, we all started somewhere! 73 - Bdale, KB0G
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