A 7el 144MHz yagi

groupe7elyagiSince almost 30 years, for my portable VHF activities, i used a F9FT 9el yagi. This one was the best i've found for this purpose, it was leigthweight, relatively cumbersome and performed quite well. Unfortunately, it broke during a contest when falling down from 7m high...

To replace my beloved antenna, i decided to build something and not to buy one. After searching some design on internet, i finally adopted DK7ZB's one. He offers several designs, and i chosed a 7 element yagi in 28 Ohms technology.

The advantages of DK7Zbs antennas are :

- Computer optimized
- Great reproductibility
- Easily assembled and dismantled. Ideal for portable operations.
- Excellent electrical characteristics, gain, pattern, F/B ratio.

The original version described on DK7ZB's page has a 3.26 m boomlength. So, i asked him if he could calculate it for a 3m boom. Aluminium tubing are sold in 6m length, and with 3m booms i would be able to build 2 antennas. The new calculated antennas have a small gain drop (about 0.35 dB)

Another advantage of this 7el is that with a 6m long alu tubing, you have enough for all elements and build 2 antennas.

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4 square vertical system

80m-4sqThis page is a short description of the four phased verticals system i've build and used. It is primarily intendend to be used on the lower bands 160m, 80m, 40m. All the principles stated here are of course valid for any other bands, but you can achieve the same game with yagi antennas easily. It is mainly built around the Collins hybrid phasing system wound on toroids.

Other feeding methods are possible and certainly better, but this one is rather simple to build and use on the battlefield. (contests, fieldays, expeditions)

Many stations use this system all around the world and it has proven his effectiveness.

  Four phased verticals on 80m (click to enlarge)

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Last products !