Canadian TV, Computing and Home Theatre Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
Hi all,

I have been lurking here and building antennas based on all the great information. First, I want to thank you all for sharing what you have found. I have built a GH6(ver.0) and DBGH6 (ver.0) and a gapless GH10(ver. 2) (all with reflector rods) and a Skyhawk. Each worked well in part but would not get all the channels I can get (primarily because they are coming from three directions).

In experimenting, I discovered an unusual setup that works better than any of the above. I took my DBGH6 apart and put it back together without reflectors and with the elements back to back about 5 inches apart. The goal was to try and get better backside reception. I have just downloaded the modelling software and was going to play around with it and figure out why this works. But as it will take me a long time to get proficient, I thought I would post here to see if any of you had heard of this or had ideas.

The first thing to add is that I am using 1/8 aluminum wire attached to either side of a 2x4 with cross piece plywood pieces. I connected the elements with a phasing feed line following the original DBGH distance from the elements. I currently have the antenna about 30 feet up on the roof. (I realize wood is not optimal, etc. but this is just a prototype to see what would happen). The phasing line is short but in three dimensions. I figured the downside in doing the double-sided would be multipath or some other such effect but I have found no issues at all with this. Instead I have found the back-to-back antennas gives me surprising strength beyond my GH10 gapless for many channels.

Using a CM7777 preamp, I find the antenna is close to omni directional, particularly around channel 26. In am in Clarence, NY and Channels 26.1-26.3 out of Jamestown are fringe but they are very strong even if I turn the antenna and try to put them in one of the nulls. I also get good results from channel 23 close to the null. On the downside, the double sided antenna does poorly with channels 38, 39 and 40.

I am not sure but I think the antenna is doing so well in the 20s because the original GH has extremely high F/B at about channel 26. As I have back to back, I am receiving front side and back side at the same time with my two element pairs. I am thinking of trying to optimize the GH element design without reflectors so that my antenna will pull in channels 38,39 and 40 with the extra power. I am also thinking of putting the elements 120 degrees to each other instead of 180.

I am curious what you all think of this setup. I can take a picture of my hack setup to show you how it works. Overall, I am getting better overall channels with this setup than any other I tried. And I am trying to understand the downside to my setup and how to further optimize it.

Cheers,

J.L.
 

·
Registered
Joined
·
7,360 Posts
Yeah, take a picture, it will explain more than a 1000 words. Also post your TVFool image.
 

·
Registered
Joined
·
221 Posts
I recommend trying just 1 element with no reflectors . Nec shows less gain and higher SWR with 2 elements joined . If using 2 elements , only hooking up 1 of them to a balun , the effect from the un-active element will be somewhat like putting reflectors behind it .
 

·
Registered
Joined
·
7,360 Posts
Heres his TVFool image:



I am currently pointing at about 190 (and 10) because my local channels come in very poorly even though they are high power (which is the reason I am building attenas ). I receive all the channels down to real channel 20 with the current orientation of the antenna.

The big surprise of this antenna is that even though I am sure there is a SWR penalty I can pull more channels than I can with my GH10 gapless. I am trying to model this in NEC but have a bit of a learning curve to get it working. Ultimately, I would like to find a setup that is similar but that boosts reception at about channel 40. Right now, I get extra power only in the 20s.
I think you'd get the most channels with two reflectorless SBGHs with NARODs, with 2 coax downleads into an A-B switch at the TV. The straight NAROD version would be easiest and best for you to reduce the gain a bit on those high powered stations in the 30's.
 

·
Registered
Joined
·
25 Posts
I would love to see the picture of your set up.. I built the SbGH10n and I get the same if not better results with just a set of plain elements as I do SBGH10
 

·
Registered
Joined
·
4,935 Posts
J.L. ur only about 15 miles from me.
What desired channels are you missing (or were you missing) before ya started playin with doubling up the elements?
Here, for UHF I use SBGH with no reflectors, splitting the difference between
Hamilton and Toronto, I can get all the local Buffalo Stations, plus these three 1 edge channels, CHCH 18, CBLT 20, and WPXJ 23. Since these 3 are 1 Edge for me, and LOS for you...think you should have fewer issues than me. You should be able to get CFTO on rf 40 as well I would think.
 
1 - 6 of 6 Posts
Top