[time-nuts] Choke Ring Pictures

[J. L. Trantham]

Just curious.  Is this antenna under a cover or are there drain holes to let
out the water when it rains?

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Brian Kirby
Sent: Saturday, March 13, 2010 10:24 PM
To: Discussion of precise time and frequency measurement; Bill Clingan
Subject: [time-nuts] Choke Ring Pictures


Several years back we had the discussion about choke ring antennas.

Dr Thomas Clark - retired NASA - Goddard Space Flight Center - I believe 
he was head of the VLBI project - made a simple choke ring antenna with 
an electrical junction box.

I made 3 sets using pie plates.  I promised somebody the pictures and 
forgot it until now.  The pictures are hosted at

http://kc0onr.com/Brian/_MG_0668.jpg
http://kc0onr.com/Brian/_MG_0669.jpg

I made these units because were I lived was surrounded by mountains 3/4 
around my property and I was at 720 feet elevation and the mountains 
varied from 1000 to 1200 feet.  I had a problem that my receivers jumped 
positions several times and I suspected a multi path problem.  I made 
the first antenna using some RF adsorbent material around the antenna.  
Helped.  After making the choke rings, the problem went away.  The other 
two units were used for carrier phase surveying.  With the Motorola 
Oncore VPZ unit and Waypoint's GrafNav software I could get resolution 
down to a little under an inch.

Brian KD4FM





_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.