The u stands for either μ or ugly :)

During geekcon08, Dror Gil asked for help building a UHF power amplifier so he could transmit old-time Israeli TV-shows from his DVD to a portable TV. I suggested not using a power amplifier at all, but just connect an antenna to the DVD RF output jack, which was rated at about 10mW output power.
The first attempt was made by connecting a single wire radiator to the RF jack:

Vertical antenna

vertical radiator

connected to the DVD's RF out port
length calculated using L=λ/4

This antenna worked quite well for close distances, a bit better than not using any radiator at all. We could receive good video and audio to a range of about one meter.
I suggested replacing the antenna with a Yagi antenna. This kind of antenna is directional, and “focuses” most of its energy at a single direction. I built it quick-n`-dirty style, and it ended up like this: uYagi This worked surprisingly well, we were able to transmit old-time TV shows across the room! Here is a short video taken by Dror demonstrating this achievement:

Statue Antenna

During geekcon I also erected a portable amateur radio station. It used a vertical antenna by using a radiator made of brass cut to a certain length for 2m communications. The supporting metal statue was acting as a ground plane. I achieved an SWR a little less of 1:2, and made a QSO using the Jerusalem repeater with Ronen, 4Z5AB. I operated the station with an IC-208H.

Statue Ground-plane Vertical

brass vertical radiator

an alligator clip was used to connect the RF cable shield to the statue

2m Transceiver



The photos were taken by Yaniv Golan,Rafael Mizrahi, Dror Gil and myself.



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projects/uyagi.txt · Last modified: 2010/03/20 20:22 by itay · []
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