[TowerTalk] Who makes the best Quad design software

[i4jmy@iol.it]

Loops have a multiple problems in the matter of multiband design since 
they respond not only to odd, but also to even harmonics and because 
loops show a greater coupling (for a stated distance) than linear 
elements.
Not only on quads, but I doubt also on good results of a 6 bands single 
boom yagi with dedicated and full size elements unless the bands are 
very much apart or yagis are placed one ahead the other (on a very long 
boom) from lower to higher bands.
Not quads, but LPDAs or trapped antennas (with all the limitations) 
with some full size (or loaded) and dedicated elements are much better 
design for antennas covering adiacent bands within one or two octaves 
and reasonable boom lenghts. 

73,
Mauri I4JMY


> ---------- Initial message -----------
> 
> From    : owner-towertalk@contesting.com
> To      : TOWERTALK@contesting.com, poster@gate.net
> Cc      : 
> Date    : Wed, 26 Jul 2000 05:05:59 -0600
> Subject : Re: [TowerTalk] Who makes the best Quad design software
> 
> 
> On Wed, 26 Jul 2000  Jack <poster@gate.net> writes:
> > 
> > Looking to make 6El Quad for 5Bands 10 thru 20
> > 
> 
> You realize that the 10M spacing will be twice the electrical
> spacing of the 20M elements assuming 5 elements per spreader.
> 
> Typically, the spacing is optimized for 10M and the designer
> just lives with the closer spacing on the lower frequencies.
> 
> The Yagi Antenna Book by W2PV shows us that gain is primarily
> a function of boom length and NOT the number of elements.  Between
> .4 and .8 wavelengths, gain is almost identical for 4, 5, and 6 
elements
> for the same boomlength.
> 
> Several years ago, there was an article in Ham Radio Magazine 
> comparing large quads and Yagi's.  The gain data was referenced
> to a HyGain TH2 which was taken to each location on a trailer
> mounted crankup tower.  The Quads did not compare well vs.
> long boom Yagi's.  
> 
> It would be interesting to understand the interactions of multiple
> quad directors for several 
different bands are interlaced on the same boom that the low
> frequency directors act as inefficient reflectors in front of the
> higher frequency elements causing destructive interference
> on the higher bands.  One must wonder about the effect of
> a 20M Quad director on the higher frequency performance.
> 
> Reflectors line up without such destructive interference.  The
> 2L Force 12 C3, C3S, and 2L Quad are good examples which
> successfully utilize this principle.
> 
> GL finding suitable software!
> 
> de  Tom  N4KG




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