killick
Well-Known Member
I would like to make a loop tv antenna for my boat. Can anyone please help with the formular for calculating the diameter.
multidirectional tv antenna
- Thread starter killick
- Start date
Beadle
Well-Known Member
The basic formula is:- wire length = 1005 / freq in MHz.
I'd be surprised if it proves successful
Most TV aerials are high gain (ie gain over a dipole) multi element Yagis. The loop does not give any gain.
For the cost of a few yards of co-ax and a bit of stiff wire its worth a play - best of luck.
I'd be surprised if it proves successful
Most TV aerials are high gain (ie gain over a dipole) multi element Yagis. The loop does not give any gain.
For the cost of a few yards of co-ax and a bit of stiff wire its worth a play - best of luck.
William_H
Well-Known Member
TV antenna
The design of a omni directional TV antenna is a tricky exercise because it is all compromises.
The above formular is OK provided you know what channel you want and hence it's frequency.
The length of a dipole will not be the same as the ideal length for a dipole wrapped around in a circle. Which seems to be the best compromise to get the omni directional bit. Generally the performance is so poor compared to what we get from a directional wide band yagi style antenna that they have to fit an amplifier both to bring the signal up and to overcome the losses of a cable which is necessary to get the antenna high enough for performance.
So unless you are in a strong reception area you will need an amplifier. The end result is that there is much to be said for buying an off the shelf antenna with amp.
Or use the formular to make a dipole and put up with its somewhat directional performance. olewill
The design of a omni directional TV antenna is a tricky exercise because it is all compromises.
The above formular is OK provided you know what channel you want and hence it's frequency.
The length of a dipole will not be the same as the ideal length for a dipole wrapped around in a circle. Which seems to be the best compromise to get the omni directional bit. Generally the performance is so poor compared to what we get from a directional wide band yagi style antenna that they have to fit an amplifier both to bring the signal up and to overcome the losses of a cable which is necessary to get the antenna high enough for performance.
So unless you are in a strong reception area you will need an amplifier. The end result is that there is much to be said for buying an off the shelf antenna with amp.
Or use the formular to make a dipole and put up with its somewhat directional performance. olewill
Deefor
Well-Known Member
An interesting read on aerials generally, especially the bit on omni's. http://www.aerialsandtv.com/touringaerials.html
tawhiri
Well-Known Member
TV antenna
Most TV is now broadcasted digtal in Europe. I don't think a loop antenna will help very much
Most TV is now broadcasted digtal in Europe. I don't think a loop antenna will help very much
johnalison
Well-Known Member
SWMBO went to Tesco's and bought a diddy little aerial which is mains powered. It sometimes works in the cabin and usually very well from under the sprayhood. It only cost about £25.
William_H
Well-Known Member
Digital TV data is carried on a carrier wave just like the old analogue TV and as such the requirements for antenna are exactly the same. It is just that being digital means picture is either perfect or non existent. olewill
