Why not consider building a patch antenna out of the copper tape that hobbyists use in making stained glass. Patch antennae are what they use on "real" rockets.
Joe Z On Fri, May 31, 2013 at 4:42 PM, Peter Hackett < [email protected]> wrote: > Casey and Bdale, thanks for the info! > > RE " ... when another newbie ham asked a similar question" > :-) you! > > Ok, I think I understand most everything. > > I did some more poking around (Casey's thread and a little Googling) > > Which got me to thinking about moving the altimeter from rocket to rocket. > > I found a web page which seemed to suggest I could strip off (in my case) > ~ 7" > of the outer casing and outer conduct of a coax cable to form the > equivalent of > a 7" wire antenna. Does that sound right? > > Give that it is true (works reasonably well) I was thinking I could buy a > (say) 5ft > sma male to <anyConnector> coax cable cut off the <anyConnector> end, > drill a cable diameter hole in the "main" side of the altimeter bay thread > the cable > through leaving enough slack to easily connect the sma male connector to > the > TeleMetrum. I would then epoxy the cable as it passes from the inside to > the > outside of altimeter bay. Then I would cut the cable to (say) 8" long on > the outside > of the altimeter bay and strip 7" of the outer case and out conductor to > form the > wire antenna. > > *Seems* like it should work. Thoughts? > > This seems like it would be a good solution because I could install a > cable/antenna > in each rocket for the price of a sma male to xx cable (~$10) > > > > On Thu, May 30, 2013 at 9:30 PM, Bdale Garbee <[email protected]> wrote: > >> 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 >> > > > _______________________________________________ > altusmetrum mailing list > [email protected] > http://lists.gag.com/mailman/listinfo/altusmetrum > >
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