Antenna - Theory .com: The Antenna Site

Antenna Basics Antenna Types Smith Charts Antenna Measurements

antenna-theory.com :: View topic - Longwire Antenna for TV Ch. 9
antenna-theory.com Forum Index antenna-theory.com
Antenna Theory
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Longwire Antenna for TV Ch. 9

 
Post new topic   Reply to topic    antenna-theory.com Forum Index -> Questions Related to Antenna Theory
View previous topic :: View next topic  
Author Message
Sushihunter
Antenna-Theory.com Newbie


Joined: 27 Jun 2011
Posts: 3

PostPosted: Mon Jun 27, 2011 8:32 am    Post subject: Longwire Antenna for TV Ch. 9 Reply with quote

Hi Everyone,

I have newly signed up to ask this question. I hope I am not repeating an earlier post...

I have need for a TV antenna which will pick up TV Ch. 9 (Canada).

I live about a mile from the transmitter antenna and there is nothing big between us. for quite some time I have used longwire antenna made from Cat5e cable strung around the living room of my home. I tied all the strands of wire together to make it one large wire, and soldered them together at each end. I then ran the wire around the room with one end connected to the center of a TV coaxial cable, and the other end connected to the shield of the same coax, thus making a loop. I also attached a short wire from the center wire connection to the FM antenna input of my FM Radio receiver so I could pick up the local radio station. It is a mobile home and thus covered with aluminum. There are two windows in the room where I concentrated most of the wire.

I was getting a signal that was good enough to watch (most of the time), but it was snowy and sometimes the audio would turn to static dependant on where I was located in the room.

I was concerned that the antenna was not getting a clear signal due to being inside and have wanted to place it on the roof, outside the aluminum barrier and at a higher elevation. I have recently done this with mixed results.

The Cat5e was not long enough, so Cat3 was used which has twisted wires. It was attached to equal lengths of the the old Cat5e to extend it to attach to the coax to the TV. The wire was run through holes in 6 2x4's that suspend the wire about 30" above the roofline and make a big horizontal loop going the entire length of the trailer and the width of it. I would estimate it at being a total length of 200 feet.

I expected to get much better results and perhaps a perfect picture and audio on both the TV and the FM radio station.

Oddly enough, there was no or very little improvement in the reception of either the TV or the FM signal.

I have tried placing a baulin that changes from 300 ohm to 72 ohm inline where the longwire joins the coax. That did not seem to make a difference.

I have noticed that moving the wire around will make the signal level change from "better than before" to "no picture or sound at all".

I have several questions:

1- Is my antenna theory of using a random length Cat3 wire to make the loop good, or is there a flaw?

2- Would I be better off replacing the Cat3 multiple-twisted pair wire with Cat5e parallel stranded wire? Or some other wire?

3- Am I correct in joining each end back to the coax - one as center lead and the other to the shielding?

4- Do I need the 300 to 72 ohm baulin to make this work? Or should I attach the wires directly to the coax?

5- The transmitter is located at about a 45 degree angle to the longest length of the longwire.

6- Is there anything I need to consider that I have missed?

Thanks for taking the time to read this! I look forward to your responses.
Back to top
View user's profile Send private message
Sushihunter
Antenna-Theory.com Newbie


Joined: 27 Jun 2011
Posts: 3

PostPosted: Fri Jul 01, 2011 11:56 pm    Post subject: Reply with quote

*bump*
Back to top
View user's profile Send private message
bigSteve
Antenna Wizard


Joined: 14 Mar 2009
Posts: 265

PostPosted: Thu Jul 07, 2011 8:32 pm    Post subject: Reply with quote

1. Why would you want a loop antenna? The peak radiation direction for a loop is up (perpendicular to the plane of the loop). I think a simple dipole or yagi would be better.


2. For the wire that you use to make the antenna, it doesn't matter, although thicker is always better for bandwidth.

3. Not entirely clear on what you're doing here.

4. The balun is optional. You should try it both ways and see if it makes a difference. I don't think 72 ohms is the impedance of your loop antenna anyway.

5.

6. Why not just make a simple half-wave dipole?
Back to top
View user's profile Send private message
Sushihunter
Antenna-Theory.com Newbie


Joined: 27 Jun 2011
Posts: 3

PostPosted: Fri Jul 08, 2011 4:00 am    Post subject: Reply with quote

bigSteve wrote:
1. Why would you want a loop antenna? The peak radiation direction for a loop is up (perpendicular to the plane of the loop). I think a simple dipole or yagi would be better.


2. For the wire that you use to make the antenna, it doesn't matter, although thicker is always better for bandwidth.

3. Not entirely clear on what you're doing here.

4. The balun is optional. You should try it both ways and see if it makes a difference. I don't think 72 ohms is the impedance of your loop antenna anyway.

5.

6. Why not just make a simple half-wave dipole?



1- I had the wire at hand and could build this without having to spend any cash. It started out as a simple long wire antenna and developed into a loop.

2- OK, thanks.

3- I have a length of standard TV coax from the TV - one end is stripped and the long wire is attached to the center wire of the coax. It then runs to the roof, around the loop, and back inside where the other end connects to the shield of the coax completing the loop.

4- I have tried with and without the baulin - not sure if it makes much difference one way or the other. I believe that the baulin should convert the loop antenna to 72 ohm for the coax to the TV. Correct?

6- Problably would have made more sense, but the longwire seemed easier to build. I am now thinking of a tuned loop now that I have the frequency for the TV channel. approx. 180.000 MHz - If I can just find the formula that I used years ago to make one for my police scanner... I recall it being about 18" or there abouts.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    antenna-theory.com Forum Index -> Questions Related to Antenna Theory All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group