I really wish I knew what I was doing!
After literally years of procrastination, I've got to make a new antenna - my landlord and Rogers have conspired to destroy the abysmal 4221 clone I had been using.
Thus the posting by ota_canuck regarding the "Scatter Forager" caught my eye as most of the Buffalo (I'm in Mississauga) stations are slightly "around the corner." By that I mean the length of my apartment building (with me in the middle of the "wrong" side) runs roughly along 138 degrees and the stations are at about 140-145 degrees, which leaves me with only the diffractive dregs (and this is after they have diffracted around two giant apartment buildings about half a kilometer away)! Still there were days when that crap clone would get one or another channel (never at the same time), so there is a bit of something floating about.
Forced to do something, I have finally grasped the rudiments of 4nec2 (mainly by finding ways to break it) and have proceeded to see what I could do in the constraints of a fixed wire grid size and a limited balcony aperture.
I may have lucked in....
It's far from ideal:
-It's a 52" by 32" monster of 2" square 16 gauge Wire fencing with five slots (one large for VHF and four small for UHF).
-The UHF pattern has a ring of side lobes, although the main lobe is true and dominant.
-Wind loading may be a problem. (One of the reasons I decided to play with a 2" by 2" grid.)
But:
-It's VHF and UHF
-It's reflectorless and flat
-According to 4nec2, the VSWR isn't too bad and the gain is decent (more so in the UHF for gain and in the VHF for VSWR).
And I'm making all sorts of wild assumptions:
-I'm assuming that I can combine (reverse splitter) the 4 UHF slots and then use a 'blocking' VHF/UHF combiner to add in the VHF.
-I'm assuming that I can simply delete either the VHF source load or the 4 UHF source loads to emulate the effect of the VHF/UHF blocking combiner when deriving the numbers.
I'd appreciate advice on those assumptions. Actually, I'd appreciate ANY advice.
So, to the numbers (as I understand them). Since I did not know whether a 'blocked' slot balun would act as a high (open) impedance or a low (straight wire), I'll simply give both:
The sieve.nec file is regrettably large as I kept blowing up 4nec2 trying to build the model with copy/moves and had to use the geometry editor.
It should be here:
http://www.wuala.com/jbkeh/Shared
Please be gentle.
I ordered the fencing last Friday. With my normal pace, maybe I'll have it up before the snow flies...
I really wish I knew what I was doing....
After literally years of procrastination, I've got to make a new antenna - my landlord and Rogers have conspired to destroy the abysmal 4221 clone I had been using.
Thus the posting by ota_canuck regarding the "Scatter Forager" caught my eye as most of the Buffalo (I'm in Mississauga) stations are slightly "around the corner." By that I mean the length of my apartment building (with me in the middle of the "wrong" side) runs roughly along 138 degrees and the stations are at about 140-145 degrees, which leaves me with only the diffractive dregs (and this is after they have diffracted around two giant apartment buildings about half a kilometer away)! Still there were days when that crap clone would get one or another channel (never at the same time), so there is a bit of something floating about.
Forced to do something, I have finally grasped the rudiments of 4nec2 (mainly by finding ways to break it) and have proceeded to see what I could do in the constraints of a fixed wire grid size and a limited balcony aperture.
I may have lucked in....
It's far from ideal:
-It's a 52" by 32" monster of 2" square 16 gauge Wire fencing with five slots (one large for VHF and four small for UHF).
-The UHF pattern has a ring of side lobes, although the main lobe is true and dominant.
-Wind loading may be a problem. (One of the reasons I decided to play with a 2" by 2" grid.)
But:
-It's VHF and UHF
-It's reflectorless and flat
-According to 4nec2, the VSWR isn't too bad and the gain is decent (more so in the UHF for gain and in the VHF for VSWR).
And I'm making all sorts of wild assumptions:
-I'm assuming that I can combine (reverse splitter) the 4 UHF slots and then use a 'blocking' VHF/UHF combiner to add in the VHF.
-I'm assuming that I can simply delete either the VHF source load or the 4 UHF source loads to emulate the effect of the VHF/UHF blocking combiner when deriving the numbers.
I'd appreciate advice on those assumptions. Actually, I'd appreciate ANY advice.
So, to the numbers (as I understand them). Since I did not know whether a 'blocked' slot balun would act as a high (open) impedance or a low (straight wire), I'll simply give both:
Code:
dbiNET GAIN(VSWR)
L H
CH 7(174) 5.6(1.37) / 5.5(1.59)
CH 13(216) 5.6(1.53) / 5.7(1.18)
CH 14(470) 11.7(2.04) / 10.8(2.59)
CH 43(647) 11.6(2.85) / 11.6(2.83)
CH 51(698) 11.9(2.96) / 12.0(2.97)
CH 69(806) 11.3(3.68) / 11.7(3.77)
It should be here:
http://www.wuala.com/jbkeh/Shared
Please be gentle.
I ordered the fencing last Friday. With my normal pace, maybe I'll have it up before the snow flies...
I really wish I knew what I was doing....