Drastic improvement in my 4 bay and 8 bay antenna reception.

[gary350]

I built some 4 bay and 8 bay antennas that all work great. I accident discovered how to improve reception. My reflector screen is located 5" from the bow ties on all of my antennas. I moved the screen out 1" at a time when I got to 10" the signal strength got noticeable stronger and kept getting stronger out to 12". Field strength peaked at 12".

I have 3 weak stations that I can receive only about 10% of the time because the signal strength is too low. Now the signal strength is well above the range where I can receive these 3 stations all the time.

http://s43.photobucket.com/albums/e358/gary350/?action=view&current=Ant-01.jpg

 

[Unregistered]

Do you think your outcome was based on the placement of the reflector for your particular situation or is it a better idea in general place it about 12"'s away from the bow ties?

 

[dkreichen1968]

Gary,

What RF channels are the signals you had the improvements on? The reflector efficiency in theory is dependant on wavelength. The other question is, did you try with the reflector at 4"? I believe that is the spacing for most commercial 4/8 bays.

 

[Fringe Reception]

The reflector efficiency in theory is dependant on wavelength. The other question is, did you try with the reflector at 4"? I believe that is the spacing for most commercial 4/8 bays.

That's right and the original and second version of the DB-2, 2-bay bow-tie antenna also use 4" spacing. EV's Kosmic SuperQuad in 'standard form' uses (about) 3 3/4" spacing but he supplies parts to increase that distance to 4 1/2" so its a tuneable-antenna (TunaTenna) LOL!

Jim

 

[Unregistered]

I brought these antennas with me to Arizona. The work much better reception than rabbit ears. 3 channels were not coming in but when I held the reflector up to attach it reception took a big increase. I decided to place the reflector behind the antenna then get several feet away it was working great. It is 22.5" tip to tip on the bow ties. The reflector is pretty close to 1/2 the length of the bow ties 12" from the reflector. My reflector was originally at 4" from the bow ties. Someone on the forum suggested I try 5" a few years ago, I changed it and it worked better.

I built 2 antennas with a wooden frame to bring with me to Arizona both have the reflector mounted at 5". I originally set the antenna up with NO reflector after I arrived. It was working fine we are only 15 miles from all the stations. All the stations are on top of South Mountain. Zip here is 85392. We watched TV with no reflector for 2 days and were picking up much

Do TVfool search for 85392 to check the frequencies. At the moment the antenna is on a small table about 3 ft off the ground in the yard. The antenna is aimed at 114 degrees with my compass.

 

[Aerial]

Aerial is my user name. Consumer production antennas are a (middle of the road) compromise design to receive the best over a wide range of tv channels. Yes , antennas that have a reflector screen such as but not limited to , 2 bay , 4 bay and 8 bay antennas , changing the reflector screen distance from the reception elements will increase the reception of some channels and at the same time decrease the reception of other channels.

 

[gary350]

I brought these antennas with me to Arizona. The work much better reception than rabbit ears. 3 channels were not coming in but when I held the reflector up to attach it reception took a big increase. I decided to place the reflector behind the antenna then get several feet away it was working great. It is 22.5" tip to tip on the bow ties. The reflector is pretty close to 1/2 the length of the bow ties 12" from the reflector. My reflector was originally at 4" from the bow ties. Someone on the forum suggested I try 5" a few years ago, I changed it and it worked better.

I built 2 antennas with a wooden frame to bring with me to Arizona both have the reflector mounted at 5". I originally set the antenna up with NO reflector after I arrived. It was working fine we are only 15 miles from all the stations. All the stations are on top of South Mountain. Zip here is 85392. We watched TV with no reflector for 2 days and were picking up much

Do TVfool search for 85392 to check the frequencies. At the moment the antenna is on a small table about 3 ft off the ground in the yard. The antenna is aimed at 114 degrees with my compass.

Wonder why this says I am unregistered?

 

[dkreichen1968]

Wonder why this says I am unregistered?

You must have posted without logging in. :becky:

 

[PhilKE3FL]

Do you think your outcome was based on the placement of the reflector for your particular situation or is it a better idea in general place it about 12"'s away from the bow ties?

I'd like the answer to your 1st question as well, isn't it supposed to be 1/4 wavelength away? As to the second one, IF 4" is 1/4 of the design frequencies wavelength, then 12" is 3/4 and that should work the same as 4". It makes more sense to use 4" since the further away a reflector is the larger it needs to be.

I was going to test this idea out as well & post it on my antenna blog, Karras' Corner, and I was looking for the "standard" reflector distance for these bow tie UHF antennas. The reason for the bow tie design is that the frequency response of the antenna depends on the outside angle (which one can translate to the inner angle) and not on the length of the antenna. It's all very interesting but I haven't yet found the relationship between the angle and the frequency response. The article I found was for amateur radio & the response was plotted for 800 MHz to 8 GHz. The antenna had an inner angle of ~ 50 degrees, most UHF TV antennas are in the 21 - 28 degrees range, why is that? That's another question I want to answer. I've already answered the length question, "will making it longer improve the upper VHF reception?" I got more from the tests than I bargained for! The information will be in my blog.

Thanks for the information about the standard distance used, I'll start there or a bit below for my quick tests once I get around to it.