Although I’m not a big fan of V/UHF, going over DK7ZB’s website I was impressed by his numerous Yagi antenna design and their good efficiency, and also, myself, eager to do some mechanical construction, I decided to try building this four elements Yagi for 430-440Mhz, to use it this summer in portable operation, mounting hiking etc.
The antenna has 7.5 dBd (9.6 dBi) gain at 436 Mhz and the SWR varies from 1.3 at the lower edge, almoust to 1.05 to midband, and 1.9 at 440 Mhz. The elements were cut and position like in the dimensions table (maybe with an error of +-0.5 mm). I tested the antenna with a Rig Expert AA-500 borrowed from a local ham friend, and the result was the same as in DK7ZB’s SWR diagram.
The boom is 500 mm long, 15 x 15 mm rectangular aluminium pipe, together with the elements, bought from a local hardware store. The elements are 8 mm diameter and 10 for the radiator. All the plastic mounting supports and pipe caps purchased from the internet.
I choose to use a BNC connector instead of N-type, because the last element, the reflector is to close to the connection box and it wasn’t space for a N…broke one box to realize that.
All the parts are easy to transport and quick assembly. I am looking now for a way to make a carry bag for it.
The antenna has 28 ohms impedance, so I used the DF9IC match to make it 50 ohm. This PCB match design is very easy to build and uses one lambda of RG 179, 75 ohm coax cable, which I bought it from ebay; I think 5-6 usd for 3 meters I spend for it.
Yeeep, I plugged the Baofeng to it…if I calculate, I think the antenna was more expensive then this little chinese radio. Also, I was brave enough to connect to my FT-817 and surprisingly it shows no SWR line.
Hope this days the weather will go better and take out the antenna to field to test it in real QSOs, maybe I could open some UHF repeater from far away.
And…already a 6 elements and an Arrow Satellite Yagis are under construction. I might get the taste for VHF & UHF from now on…