Looking for some measurements

Larry1

SatelliteGuys Pro
Original poster
Aug 24, 2005
1,594
138
Port Hope, ON Canada
After seeing the different posts of ganging multiple antenna to achieve higher gain, it has got me thinking of making a string of bowtie antenna to go across the peak of the roof to achieve a ultra high gain antenna. What I am in need of is someone to take a few measurements for me. With the multi bowtie antennas like the Channel Master 4228, what is the length of the active elements (the bowtie). How far apart are the bowties spaced vertically and horizontally from each other, as well as how far from the reflector are they spaced. It should be easy to gang a large string of then across the peak of the roof to achieve a high gain array.
Currently I have a homemade antenna on a 20ft tower, with a 10ft mast above that. The antenna output is fed into a 300 to 75 ohn balum and then into a Channel Master 7775 pre amp. With this configuration I am getting some signals with great strength, but my problem is that directly in my line of sight I have some trees. (about 80ft to the south of me) To place the antenna line of sight over these trees would require a tower of 60 to 80ft. I have found that even a 2 foot increase in height changes the signal from 68 to 75. Another foot higher and again an increase in signal strength. The atmosphere plays a big roll in the reception of signals for me. Most of my stations are 60 to 80 miles away. The OTA reception is a hobby for me, as I use satellite and cable for my TV. Maybe in the future I will get a higher tower.
Here are a couple of pictures of my project antenna.
 

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Looks good

That antenna you have looks good. Getting it higher is the answer. UHF..HD.....they are a line of sight signal. Straight at you so.....the farther away, the higher you need to be. Not like regular TV channels 2-13.....come at you in waves. So you could build whatever you want on your rooftop and it will not perform as well as what you already have if it was higher in the air. I'm in the woods and My antenna is 60ft up and I'm about 35 miles from stations. At fooftop I could not get anything.
 
Larry1 said:
It should be easy to gang a large string of then across the peak of the roof to achieve a high gain array.

There is a practical limit to the size of any broadside array. You can't just keep adding active elements because the spherical RF phasefront must reach each element at the same time for the active elements to add in-phase. At some point, probably not much more than the 8 elements like on the 4228, additional elements will begin to add out-of-phase and actually reduce the gain of the array. This is the reason stacking antennas often produces less than ideal resuts.
 

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