Hi ….. but the original helix antennas (at NBS) were not done quite right. They *did* have gain straight up. They re-scaled them (for a better pattern) later on. I seem to recall it being height to radius, but that probably isn't right.
Bob On Oct 11, 2013, at 3:45 AM, REEVES Paul <[email protected]> wrote: > Hi Bob, > > Not quite true, the first couple of sentences are ok but the helix antennas > used for GPS are quadrifilar volute helices, not the longer axial mode type, > and their gain characteristic can be modified to provide an almost perfect > pattern for satellite reception with a 'flat-top' elevation response and > higher gain over the 30-60(-ish) degree area. > > regards, > > Paul G8GJA > > >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On >> Behalf Of Bob Camp >> Sent: 11 October 2013 01:03 >> To: Bob Stewart; Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Choke Ring Antenna - Patch Placement? > > .......... >> An ideal GPS antenna would not have a lot of gain straight overhead. You >> have less atmospheric loss in that direction. What you would >want is an >> antenna that has some gain at 30 to 60 degrees. That was the issue with the >> helix antennas. They have gain straight up >(and thus less at other angles). > >> Bob > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
