10dB WLAN Yagi

Paul Marsh G7EYT
pjmarsh@frars.org.uk
http://www.frars.org.uk

for point-to-point WLAN applications, often a yagi provides a simple and low cost solution at the antenna side of things. FRARS members have been developing a yagi over the past few months.

Using yagi design software mainly intended for the amateur radio community, this antenna has been modeled and tweaked.

The inset picture shows an initial production of 5 yagi element sets. We decided that it would have to be simple to build with a minimum fuss, and have repeatable results. The feeding of this antenna is an issue at the moment, and we are working to create a simple feed design.

Feeds that have been successfully tried include the folded dipole with ut141 matching harness and a feed similar to the hb9cv antenna.

Another feed possibility is using an etched PCB antenna, but this is under investigation as PCB is lossy at 2.4Ghz.

The picture below shows a polar plot during the development of the initial antenna. Carl, G6NLC has developed software and hardware to automagically create a polar plot of any antenna.

The polar ploting device will be a feature of the FRARS Wireless LAN antenna testing day.

Now we have established a simple yagi design, this can be scaled to other frequencies.

Phoenix Precission Engineering based in Poole kindly manufactured the initial run of antennas for us at a very reasonable price! Thanks go to them.