Inernational HAM Magazine 100% HAM RADIO - arkansas ares races
Inernational HAM Magazine 100% HAM RADIO - arkansas ares races
Inernational HAM Magazine 100% HAM RADIO - arkansas ares races
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A Solution?<br />
This design came about in the search for better gain at the horizon and yet still make<br />
construction easy. After a lot of discussion, experimenting and some frantic NEC modeling John<br />
Boyer came up with the dimensions for this one.<br />
As you can see from the polar diagram above, this model exhibits a good compromise between<br />
the two previous examples. The +dB figures give the direction of highest gain, the figures the<br />
direction of greatest loss.<br />
John and myself have both built this one and find it has excellent reception properties. Its quite<br />
easy to get full horizon to horizon passes!<br />
Try it you'll not be disappointed<br />
Construction notes and dimensions<br />
The finished model should look like the one<br />
labeled "Tall narrow QHA" at the top of this page.<br />
Element Dimensions<br />
Mast 1.5m of 32mm (1 1/4") PVC waste pipe.<br />
Elements 8mm (3/8") minibore soft copper tube<br />
8 copper elbows for the corners.<br />
2 190mm lengths bottom horizontal tubes<br />
2 903mm lengths short helix elements<br />
2 1002mm lengths long helix elements<br />
4 90mm lengths top horizontal elements<br />
Note these are cutting dimensions and assume<br />
that 90 degree elbows NOT bends are used The<br />
dimensions on the drawing are from centre to<br />
centre of the respective elements you may have<br />
to adjust your cutting sizes accordingly.<br />
4 selftapping screws for feed.<br />
Suitable length of RG58 or UR43 for balun and<br />
feed.<br />
32mm cap to plug top end of mast.<br />
[ <strong>HAM</strong>MAG N.14 March 2010 ]
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