[Antennaware] Bobtails Half Squares with a twist

[Lonney Harper]

Hi,


I'm new here,


I caught the low band DX bug a few months ago - specifically 80 and 40m. I would post this idea/question to the top band reflector, but its stated they're 160m only, and this is not a 160m band antenna.


My goal is some gain in SW/NE directions on both bands from one antenna - space is limited, and I want to keep the place visually appealing with-in reason - e.g. limit the number of antennas, keep them simple and neat.


I have read most of ON4UN's low band DX book, and pondered many different ideas. The half squares and bobtails I like, these are voltage fed and current maximums are up high. But to orientate them for SW/NE requires some infrastructure investment as I don't have trees in the right places :-\ I have however come up with a way to configure a 40m bobtail to function as a half square on 80m - that project is going to wait for another day due to the effort required for the end supports in my situation.


Now, with end-fire antennas, life is much easier when it comes to trying things out due to where trees are etc :-)


By chance I stumbled upon this a few days ago, looks like its from an old book:


https://www.n4lcd.com/wireantennas/132-Double_Bobtail_Ant_20m.jpg


Essentially its a 20m Half Square with a 180 degree phase shift which causes it to become end-fire. I wonder if anyone has built and used one, or for the more knowledgeable will it even work as advertised? I've never seen this trick with the phase shift in a half square before anywhere. 


I'd scale it for 40m and operate it in the end fire mode. Per ON4UN's low band DX book, if the far end of a half square is grounded it operates as two top loaded in phase verticals at half the frequency - in my case 80m. This also produces an end-fire pattern (with the phase shifting section isolated and bypassed). Basically a dual band antenna with some switched matching at the feed point and far end as needed for each band resulting in end fire patterns on both bands.


Comments, suggestions, thoughts?


- Lonney
KL3NO
Puyallup WA