20 Meter Antenna Upgrade

The hex beam is still a possibility and with both Hamcon Colorado and Dayton coming up vendors and antenna gurus may offer some better insight.  A second possibility is a phased vertical array with just two elements.  One vertical is already in place,  the LNZ/PAR EF-20.  Per The ARRL Antenna Book by adding a second one a gain of 4.8 dB at 15 degrees take off can be obtained.  For that configuration the feeds would be shifted 0 degrees.  In other words they would be fed with a tee adapter and equal lengths of coax.  Easy peasy. Highest gain is predicted at a separation of 5/8 wavelengths which is about 44 feet. The gain is approximately what is predicted from the current inverted vee at 39 feet but the difference in azimuth pattern and in polarization should help.  Possibly aiming it 90 degrees from the inverted vee could fill in the null off the ends (although vees aren’t supposed to have the strong null like a dipole ).  It will be easy to move one vertical or the other to change direction  later.  Already on hand from the junk box is a second EF-20 and scrap LNR-400 coax.  The only item needed is a second fiberglass pole which can be purchased at Dayton.  It’s not going to equal a hex beam probably but it might be enough help the hex beam won’t be needed. Seems like a logical next step plus there will be knowledge gained by trying phased verticals for the first time.  Here is a look at the patterns predicted by EZNEC which closely follow the drawings in The ARRL Antenna Book.

Screenshot 2016-05-12 09.07.11

Screenshot 2016-05-12 09.07.04

June 11, 2016 update:  All the parts are sitting in the garage or on my bench waiting for the ambition to get them installed.  Holding up the progress somewhat is the balun.  I wound a 2:1 unun using the Jerry Sevick book, Building and Using Baluns and Ununs.  It needs to be mounted in a Bud box and measured.  Trying to measure it with it’s original long leads is not yielding accurate results.  Progress is interrupted temporarily by the building of the second remote base.

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