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2m quad antenna

This page was last updated : 11-Mar-20 23:09:08

2m window quad antenna

A few weeks a go I found a stock of suction cups towel holders in my workshop (proberbly bought them years ago) and looking at them the idea came to build a 2m quad antenna that could stick to a window with these suction cups.

The quad antenna is bascily a full wave square antenna which has sides of 1/4 lambda. The impadance is aprx 106 Ohm so some matching needs te be done. But when you use a piece of 75 ohm coax with a length of 1/4 lambda * velocity factor it will match to a 50 ohm antenna system.

THe basic design is shown below.

Instead of using the suction cups directly to to hold the wire, i wanted to make rectangular pieces of  PE which could hold the suction cup and hold the wire preventing it for moving. For the PE I used PE chopping boards bought at a local house hold shop which is ideal for antenna building (tested it in the microwave).

Some details.

This is one corner holder

Now with the sucton cup pressed in it.

The matching section holder.

Again with the suction cup installed.

Every thing evenly distributed.

And the 2m quad sticked to my shack window.

The SWR also looks good. It's a bit out of band, but that probably because of the matching section which is a little to short (will try to make a new one with a longer matching section). But for the 2m band in PA (144Mhz - 146Mhz) the very low SWR 1:1.2 is fully acceptable.

But the proof on the pudding is in the tasting and turns out that it works great. With just 100mW I could open a hamradiorepeater PI3TWE 28km away and had a noise free qso with 2 fellow hams. This antenna will be used for holiday style setups. 

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