VU2PPP
A-655
Sector-19
Noida, U.P 201301
ph: 09811212386
alt: 09811971176
praveen
Blue-Bird
70 cm 6 elements Yagi antenna
Here are constructional details of UHF Yagi beam antenna.
1. The antenna is based on design by ON6MU
2. The antenna is fed by a low cost, low loss foam cable RG6. The cable has Aluminium foil & mesh braid shielding.
(refer to Tips & Tricks section of this site for a simple method for soldering Aluminium braid of the cable)
3. A Bazooka Balun has been used at the antenna feed point of the cable. This is a simple and very effective method for unbalance to balance feed.
(Theoretical details of Bazooka Balun are as given on the side column)
4. Theoretical gain of the antenna is 9dbD with front to back ratio of 13db.
5. E-shaped Aluminium channel has been used for boom and all the elements. This is because of the availability of this channel in my work-shop. Aluminium tubes of circular or rectagular cross section can be used without making any difference in the performance of the antenna.
6. No matching network was used to feed the RG6, 75 ohms cable, from the 50 ohms output of UHF transceiver. The SWR, as measured on my home-brewed meter, showed less than 1.5 across the complete 70 cm band.
7. The performance of the antenna was checked by the on-air contacts and was found to be very good.
8. No trimming may be required in adjustment of the antenna elements for tuning purposes if the given dimensions are followed closely. Mine did not require any trimming.
All figures can be enlarged by pressing the sign on the lower right hand side of the figures.
Basic dimensions of the antenna
Details of feed point & bazooka Balun
Details of Bazooka Balun
You may Google for detailed explaination of Bazook Balun >
dedicated to those who tinker around in their work shop to innovate and create .....
A-655
Sector-19
Noida, U.P 201301
ph: 09811212386
alt: 09811971176
praveen