Wednesday, November 13, 2019

28 metre light pole - this time as an antenna on 3.5 MHz

My video from last week showing a 28 metre light pole being coupled into to operate as an antenna on 1.8 MHz was hugely popular with 12 000 views to date. 

A couple of days ago I was out again trying it on 3.5 MHz. This time I did a test with the feed loop moved away to the pole to see what would happen to signals. Though conditions were varying the pole appeared to have an effect. 

Watch what I did in the video below.  

There are definitely refinements needed. For example the VSWR is showing somewhat high so further work is needed (beyond the L-match network) if using it with a transceiver with a 50 ohm output. 

A thing you should be aware of is the different antenna requirements for 160m and 80m. A major propagation mode on 160m is ground wave for contacts within about 100km. That needs a vertical antenna. Whereas on 80m and higher frequency bands the ground wave is less but skywave becomes more important. That requires a high angle radiator such as a low dipole. A vertical may not necessarily be the best type of antenna. So although the 28m pole looks impressive you actually might get better results if you were to use the 9m squid pole as a support for an inverted vee dipole or end-fed. But the vertical has potential for DX contacts which need a low radiation angle. 

PS: I've now written six books on various aspects of amateur radio. Whether you experiment with antennas, enjoy QRP or are starting out in radio there's a book for you. Find out more here.

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