[byebye_cable]

For the Gold Standard SBGH antennas here;
http://www.jedsoft.org/fun/antennas/dtv/gh.html#toc-2

...can these be build using 6 gauge copper wire for the reflectors (as well as the element) - or would that be too soft? These half-wave reflectors range in size from 12 5/16" for the GH4 (probably fine) up to 21 7/8" for the GH10. Might a 21 7/8" a copper wire supported on only one end start to sag after awhile?

2nq q, how do you interpret F/B ratio charts (again on http://www.jedsoft.org/fun/antennas/dtv/gh.html#toc-1 )? I did my research on wiki & know F/B ratio refers to the antenna's ability to pic up signal from the rear. The implication in the noted site is that a high F/B ratio is good - is this because rear-rejection of signals is considered good or do I have that backwards? Just a bit confused - if I got additional channels from the rear I'd be happy (I realize they might interfere with the channels from the front).

 

[300ohm]

Might a 21 7/8" a copper wire supported on only one end start to sag after awhile?

Yes, 6 gauge wire that long will sag. 3/8 inch tubing from old antennas is the way to go for reflectors. Grey pvc gutter ferrules make great spacers for that tubing.
Cheap old aluminum arrows are another popular option, as is aluminum rod from Metal Supermarket.

The implication in the noted site is that a high F/B ratio is good

Yep, not everyone thinks a high F/B ratio is good. In my situation, its not what I look for. Generally high F/B ratio is goes long with higher gain. A high F/B ratio is also desirable if you have multipath signals.
My DBGH colinear rod picks up 16 - 21 NM stations 50 miles away from the rear just fine. My DBGH mesh does a poorer job of that. The mesh makes for a higher F/B ratio.

 

[byebye_cable]

So from hdtvprimer; "since gains and F/B ratios are usually given in dB, you normally get the F/B figure by subtracting the rearward gain from the forward gain (both in dB)"

So can I say;

F/B Ratio = Forward Gain - Rear Gain

therefore

Rear Gain = Forward Gain - F/B Ratio

Since the GH6 has a fairly flat forward Net Forward Gain of about 14 and an F/B ratio of about 11 (at the frequency I'm interested in) this would become;

Rear Gain = 14 - 11 = 3 (again, at the freq I want)

Am I still correct here? And if so - is there any prospect of picking up a station 49.9 miles distant, rated 1Edge and 18.0 NM dB with the 3dB gain out of the rear of the antenna?

 

[300ohm]

And if so - is there any prospect of picking up a station 49.9 miles distant, rated 1Edge and 18.0 NM dB with the 3dB gain out of the rear of the antenna?

I do and get 70 - 80% on the meter, but my stations arent 1 edge. 1 edge stations can be tricky, so you really wont know until you try it.