The DF9CY Three-Element Antenna for 28 MHz
A better view of the 3 element for 28 (and the 6 element for 50 MHz)
My 3-Element for 28 MHz antenna is mounted below my 6 element for 50 MHz
The 3 element is a commercial antenna by PAN International, which I slightly modified for good performance on the 10m Amateur-Radio band.
Design Frequency: 28.300 MHz
This antenna is a commercial CB Radio antenna distributed by PAN International. For this kind of antenna it looked quite robust and indeed it survived a wind storm with wind speeds up to 160 km/h.
Feeding the antenna
This antenna is fed by a gamma match. Setting up this antenna was very easy. Position of the gamma match as approximately moving the bracket as far inside as possible and the inner conductor "looks out" by 70 mm at the end.
Modify the elements
Calculating the antenna with EZNEC gave already very good results. The redesign for 28.270 MHz resulted in shorting each elements' end by 40 mm. This is indeed very easy, as there exist two holes for self-cutting screws separated by 40 mm. Move the outer element in by one hole, fix it with a screw and drill a hole for the second screw. Ready. You shall better not use the screws delivered with the antenna as they tend to oxidation (rust) very quickly. I bought a complete new V2A set of screws and I have no problems. The elements are electrically connected to the boom. What I dislike is the SO239 connector "popped" to a sheet of metal. I will replace this by a N-Connector now.
The antenna is up since October 1998 and performance is good. Contacts were made with all continents using my TS690 with about 90 Watts output. It does not perform as our "pile-up-cracker" does, but I feel it works better than a tribander. The antenna is installed at about 9 m above ground. This is indeed not very high, but the surrounding terrain descents in most directions putting the antenna virtually to a higher position. The feedline I use is a low-loss UHF cable (AirCell 2000) with less than 0.4 dB of loss on the 22m run. I also used it with 750 Watts output from a 3-500 for a while and it did a fine job.
Elevation diagram. Vertical attenuation is around 10 dB.
If you want to have more background knowledge on antennas and how-to make them, you will find an ultimate resource here:
L.B.Cebik W4RNL ultimate ANTENNA Site. A must !
Text and All Images are Copyright by Christoph Petermann DF9CY
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