For Tim's excellent description of this patch feed, see http://www.qsl.net/k3tz/index.html)

Here are the parts I used to build it. The two aluminum plates are cut from a 6"x12" piece of aluminum purchased at HomeDepot. The coffee can was not used (yet). Notice the N-connector is a male.

Here it is being tested against a helix+cup, using the AO-40 beacon as a test signal. The DSS dish is 18" x 24" and the downconverter is a TSI 3731 from K5GNA. The helix was a 4-1/4 turn model inside a "cup" (coffee can) from an earlier antenna experiment. The patch was 1 S-unit better delta S/N (about 3 dB on the FT-100) with a quieter background. I found the patch, rotated to 45 degrees, with the "cut" corners horizontal, produced the best signal. There was at least 1 full S-unit of difference between the best and worst orientations for the patch. Clearly, this patch will over-illuminate this large f/D antenna, so an improvement is certainly possible with a collar or "cup" around the back plate.

Here is the completed unit on 3-Feb-02. TG9AJR, Juan Carlos (sometimes on UO-14), was visiting Houston. KK5DO picked him up at the airport. Allen, N5AFV, and I joined for lunch, and then we went outside for an AO-40 "demo." That is Juan, Allen, and me in the pic behind my truck. Signals were very strong with SSB about 57 (we listend to lots of QSO's, including W6ZQ and XE1MEX that I recall) and the beacon was 7 S-units above the noise!

And here I was at the Smithville swapfest 14-Feb-02, in the cold, dawn light, listening to the beacon boom in at 5-6 S-units above the noise. K5EM and AG5RS helped setup. Using a Arrow Antenna on 70 cm, I made a QSO with KE4AZN (although he complained my uplink was distorted) then scurried inside to get warm. Notice the high-tech elevation control mechanism.

In the latest testing I have found a 3/8" ring "collar" improves the S/N slightly (about 1 S-unit).

Here is the the patch with collar and a small beam connected to my FT-100 at the Katy ARS swapfest.

Here is the patch mounted on a 2' K5GNA dish using the 3733 d/c. This is the "P5 Special" being tested on the air before being sent to North Korea for AO-40 operation. Note the dish has been "converted" to 26" round with aluminum screen mesh. (C) 2002, Gerald R. Brown, K5OE

Here is the experimental dual-band patch feed built for Field Day 2002. The design uses the L-band element as the reflector for the S-band element. The 6" round reflector started life as a 6x6" double-sided circuit board. This feed worked extremely well on L-band but was a poor performer on S-band. Later testing showed the S-band patch was too-closely harmonically related to the L-band element to use it as a reflector. Later developments added a separate reflector for the S-band patch.

And here is that feed mounted on Ron, AG5RS's antenna at his farm in Brookshire, Texas. It was a fun Field Day 2002!

Finally, here is my latest dual-band feed mounted on my 1.2 m converted-UHF-TV-dish (covered with alum. mesh).