Coax as an antenna?

I recently moved into a 3 bedroom rent house that the previous occupants wired almost every room for television. I have no need for cable, only have two Televisions (one for the living room and one for the kitchen), and have been doing just fine with the broad cast stations. I know I’ll need to buy an antenna, but I was wondering with all the coax cable running through the house that it wouldn’t act like a huge antenna?

As a side question: Does the quality of the coax from the antenna to my television really matter?

No. One feature of coax is that the signal is contained between the inner and outer conductors, and doesn’t leak in or out through the outer conductor.

As for the coax quality, that matters more for a long run, say from the roof. If you’re talking about the last six feet from a coax outlet in the wall to your TV, the coax per se isn’t going to matter that much, but you’d want the connectors to not be crappy.

I may be wrong, but the outer sheath of the coax does exactly the opposite of what an antenna does - it insulates the core from electromagnetic “interference” - in your case, it would insulate the core wire from the TV signal.

I guess if you exposed a length of core at one end, then twisted the end of the sheath around it to give it a good connection to the core wire, that might turn it into a receiver?

It might, depending where the end of the cable ends. When many public service agencies (police, fire, etc.) went to a trunked 800MHZ system I bought a special antenna from Grove. All it turned out to be was a coax cable with a BNC adapter at the end to attach to my scanner. You could hang the cable underneath the eves of your house and feed it in through a window, or you hang it around the wall or frame of a room.

And you know what? It works! It really improved the reception over the rubber duck antenna. especially for transmissions that were coming from many miles away.


It could, what you want to do is use the center lead without connecting the outer metallic part. You can do this by not screwing it on and leaving a gap, or pulling off the connector and pulling back the outer wires/foil so just the center lead goes in.

This may not work if the other part is grounded, which would be a a connector or splitter, it would have a ground wire, which you could remove.

as stated the coax won’t work by itself.

you could make a dipole antenna (a wire connected to the center conductor, another wire connected to the coax shield) to receive stations if you have a strong signal. though if you have a strong signal a rabbit ear antenna with a UHF loop or bowtie may be all you need at each tv set.

if you need more than that there are antennas you can make from electrical wire.

you need to identify the channels you want (the real channels in the USA for DTV that are broadcast on not the virtual channels (what the stations name themself)), the signal strength at your location and direction.

i have made tv antennas for myself and others with electrical wire and wood (cost of a few dollars) that work from 30 and 70 miles distant.

I remember back in the day when my Atari when turned off would pick up one of the channels from the cable in the house. Never did figure out how that happened. But it does show the cable sort of acting like an antenna.

Generally, coax is meant to carry signals between its center and shield, and be insensitive to things outside.

But there are plenty of antenna designs that change this, with all sorts of tricks like connecting the two together, or interrupting the shield, or switching the two. I think their popularity stems in part from the clever and thought-provoking ways they upset the traditional roles of the two conductors.

Generally if you have coax wired in the normal way, all the stuff throughout the house will not act as an antenna, though it will act as a reflector and could influence the way an ordinary antenna worked nearby. To make an extreme example, suppose you wired a meshwork of coax in the shape of a parabolic dish. This would focus radio energy like any other conductive paraboloid.