I put pictures out on the net years ago. I put two rulers in the pictures to show folks the dimensions. Back then we used the stock Motorola Antenna97, a patch antenna.
I have a set of the antennas stored. When I get to the storage location this weekend, I will try to remember to shoot another set of pictures. As I recall, I found a common size aluminum cake pan set of 5 pans that came close to the needed choke ring dimensions. The smallest pan was turned over and some of the rim was removed and the antenna was glued to it with epoxies. Then then remaining pans were used face up and centered via a bolt. I used some square aluminum tubing on the bottom to attach pipe clamps, and it was mounted to a pipe mount. The other two sets that I have, are attached to adjustable laser level mounts, which is attached to surveying tripods. I did some carrier phase surveying using the Motorola Oncore VP gps receivers and in general had positioning repeatability of just under 3/4 of an inch. Of the bat, somewhere either NASA or NGS published data (on the web) on choke ring antennas back when choke rings first came out. They had photos and measured dimensions and some performance data on the electrical phase centers/error on these antennas. I believe the test were performed in Maryland, Virginia or DC area. Also, I do not remember if it was on this list or the earlier TAPR list, it was discussed using the choke ring assembly off of a 3.7-4.2 Ghz satellite TVRO feedhorn assembly. Choke rings can be wide bandwidth and low "Q" or narrow band and high "Q". If Dr. Clark is still on the list, he may be able to enlighten everybody. Brian KD4FM WB6BNQ wrote: > Hi Brian, > > Have you ever published your efforts with making the choke ring out of pie > plates > ? If so do you have that available with, hopefully, pictures, deminsions and > so > forth ? I have one of the Timing 2000 antennas. Did you use the choke ring > pie > plate with it ? > > thanks, > > 73....Bill....WB6BNQ > > Brian Kirby wrote: > > >> The Motorola Timing 2000 and 3000 antennas are patch antennas. They >> have a pointed radome. The have very little ground plane, which reduces >> reception near the ground, which is desirable because of multipath >> effects. They also have quite a bit of filtering, so transmitting >> antennas near the units, will not affect them. >> >> If you are not having a problem with multipath, a regular patch type >> antenna probally from anybody should work well. >> >> If you are having multipath problems a timing antenna should help or a >> choke ring assembly should help. I have built choke rings out of pie >> plates, and Dr. Tom Clark made a basic choke assembly using a common >> electric junction box. >> >> I had problems with multipath because of mountains about 3/5 around my >> location. I changed the look angles so my receivers only receive above >> 20 degrees above the horizon and I use timing antennas now. >> >> Brian KD4FM >> >> Matt Ettus wrote: >> >>> Is there really anything in particular which is different about the >>> antenna requirements of timing receivers as compared to ordinary >>> high-quality receivers? The timing antennas seem to be in pointy >>> radomes, so that tells me they are probably quad-helixes rather than >>> patch antennas. How is that advantageous for timing in particular? >>> >>> Thanks, >>> Matt >>> >>> _______________________________________________ >>> 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. >>> >>> >>> >> _______________________________________________ >> 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. >> > > > _______________________________________________ > 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. > > _______________________________________________ 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.