[Elecraft] T.G.M. Hybrid Quad

Tue Apr 22 15:56:00 2003

Date: Mon, 21 Apr 2003 15:31:07 -1000 

Hello, 

I was wondering if anyone has used the T.G.M MQ-1 or MQ-2 with their K2 and if so, how well the antenna tuner performed with it. I was considering the MQ-2 since it has mostly 5-6 dBd gain across 6 bands and its small footprint is just what I need. 

Don't have one but don't be misled into the trap of gain versus bandwidth versus "radiation resistance".  Nothing else matters if your antenna's radiation resistance is poor (low).  That's where the "dummy load" analogy comes from.
It appears to be a relatively narrow bandwidth antenna. I kind of understand that performance is not directly related to low SWR (i.e. dummy load) but I would be interested in opinions of how gain would be affected as the antenna bandwidth is extended with the KAT100. 

Regardless of which antenna you select the "performance" is related to several components but mostly by "Radiation Resistance" (sometimes incorrectly coorelated to "efficiency").  Radiation resistance has to do with antenna modeling but the basic thing is that most of those "numbers" that you see in antenna ads are pretty much meaningless UNLESS your antenna installation situation closely matches the manufacturer's antenna test range (usually not).  So to answer your question more accurately the "bandwidth and gain" have more to do with "how high (above everything else including your roof) and on what (non-metal?)" you will be mounting it on.  You can "stuff RF energy into it" via a KAT100 (maybe) but how effectively it radiates depends on how it is installed, how it is fed, and how it was adjusted/tuned.  You also need to look at the plots of that 5-6 dB of gain (compared to an isopole or a dipole?) to determine what it may actually do for you even in an "ideal", optimized installation.
So basically on any "compact" antenna design you can pretty much write off at least half of those "numbers" due to practical limitations of an installation versus an antenna test range facility (is 2.5-3dB really all that impressive now?).  Then your actual numbers go down from there (more like 1-2 dB).  But hey, if due to all kind of constraints it is all you can put up that will STAY up, it beats nothing (probably at a hefty price though).  Be aware that this type of antenna (the old Erie, PA ones) need to be tuned properly and do not handle any abuse very well. 
All things considered they work "OK"but I often wonder, for all their grief, if a suitable trap-dipole, G5RV, or open-wire line fed dipole, up at least as high or higher wouldn't do a much better job for far cheaper a price.

Tom M., WA3UZI

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