Jim, > There's a new "choke ring" style antenna (patented, of course, and they > deserve it) which uses spikes instead of solid rings. And, they wrap the > choke over a hemispherical surface as opposed to on a plane. > > Much tougher to design and fabricate (no buying sets of cake pans any > more), but if you want to differentiate yourself from the horde of > Ashtech/D&M style chokes, you need something.
There are actually two new designs one coming from Novatel where the "rings" are put in a pyramide/cone. The "rings" are also shopped of into small ring segments. http://webone.novatel.ca/assets/Documents/Papers/GNSS-750.pdf The other, coming as a response to the Novatel antenna, is from Topcon which uses spikes. http://www.topconpositioning.com/products/gps/antennas/pn-a5 http://www.topconpositioning.com/sites/default/files/PN-A5_white_paper.pdf > At JPL, we also use what's called a "helibowl" for ground testing. It's > a quad helix or other element inside a bowl. Doesn't have much pattern > close to the horizon. I suspect you can google and find more details, > or if people are interested, I can ask around about design information. I am interested in more information. Will look for whats later in the thread. I have a situation where there is interference coming from a specific direction (close to the horizon). Is it feasible to block/attenuate/absorb L-band signals from one direction? -- Björn _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.