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SWR Measurement

Top AntennaThe antenna is a 5.9 meter ½ λ vertical antenna mounted on a 4 meter mast in my garden about 1 meter from my house veranda. The brand is "TOP RF 1/2 HF" and I haven't found this on Internet, except from a radio shop in Tampere, Finland, where I bought one for € 127 this summer. It needs a tuner on all bands, and even works OK on the CB band.

Measurements are acquired by my miniVNA analyzer show the following SWR ratio over the whole band from 1.8 MHz up to 50 MHz. The accuracy is estimated to be better than ± 10 %.

SWR diagram

Note that this antenna is not a performer on the low bands, i.e. from 3 MHz and lower. Perhaps this will change if the antenna is higher above ground.

It works well with a tuner over the rest of the amateur bands. It even shows a useable VSWR ratio on the 2 meter band (though not documented in this graph). The graph shows a neat 1:1 SWR near 20 MHz as it should do according to the length, without further trimming.

By using this antenna, I have logged some interesting PSK QSOs with Germany, Holland, Russia and France to mention a few.

Next step is to position the antenna at least 1.5 meter higher above ground (5,5 meters), in 1,5 meter intervals, and do a new SWR measurement for each new position.

 

Antenna adjustment 10.02.2010

After adjusting this vertical antenna, it shows a better respons on all amateur bands.

Click on image to enlarge

This diagram is produced from my own MiniVNA program. The red line shows a 3.3:1 SWR on 21 MHz, and the thin light-red line shows the reflected power i percent for all bands. On 14.12 MHz, SWR is 4.1:1, and on 29.5 MHz the SWR is 3:1.

SWR on the 80m band is approx. 7.5:1 on 3.7 MHz

 

 


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