DJ9BV yagi for 144MHz
I just started building a new yagi antenna for 144MHz. I used to work with short yagi’s, based on DL6WU, with 6 elements. These antenna’s were about 2m long. I stacked them, tested them both vertically and vertically polarized/stacked, etc. I did lots of DX using these antenna’s. After a long period without radio activity I finally decided to start again with the hobby and try another antenna design.
Since I like the DL6WU design, I looked arround for more variations on DL6WU. I finally found a very interesting article of DJ9BV, who redesigned the DL6WU longyagis to minimize the number of side lobs. My short yagis were also optimized for minimum side lobs, which I really like. I even want to pay some gain in return of a clean radiation pattern. I immediately wanted to try this design.
The construction will be the same as I used for my other yagis: 20x20mm square aluminium bars, 3.3mm aluminium elements (welding rods) mounted through the boom using aquarium tube (those green tubes, normally used to put some air bubbles into your aquarium) as insulator, a VERON dipole and a standard antenna mounting bracket which you can buy on every radio market. There is one challenge: for a long yagi I will need a long boom. I don’t know where to buy a boom of 10m length, apart from how I would ever transport it… So I will need to build some kind of mounting to connect several tubes together.
June 30th, 2006 Yesterday evening I started building the antenna. I bought bars of 250cm earlier this year, and today I builded the first part. It is the rear end of the antenna, including the reflector and the driven element. The bar allowed me to mount 5 directors. I put the antenna on a pole and did some measurements. The results were great: I heard several beacons in Belgium and Germany, and heard a French radio amateur. I tested the SWR, which was 1:1.0 at 144.2 MHz (really, the reflected power was almost zero, the “right” pointer on my meter didn’t move! On 145.8 MHz it was 1:1.3, which is still very nice.
July 1th, 2007 I used the antenna during the REC fieldday. Unfortunately I didn’t have much time to test it, and when we broke up, the tower with the antenna fell down. The dipole was broken, and all elements were misformed. Not that it was a big problem, I was not really convinced about the results of this antenna…