So you’ve just bought a new radio scanner or found your old one and fancy diving back into the hobby but there’s no dedicated scanner antenna. Depending on how much height your home QTH has its very probable to get a good response from any built in telescopic but something mounted high outside is better.
You know there’s a few antennas up on the roof with coax running into you home but which one is going to play nice with the scanner.
Any coax in your home is more likely to have a television antenna on the other end unless you (or previous occupants) have taken part in other sides of the radio hobby (CB, shortwave etc).
With the way TV technology has changed over the years the age of the antenna determines the frequencies its optimized for.
The one major problem with this type of antenna is the way its designed to be highly directional.
This isn’t going to be much of an issue with local signals but any distance signals arriving at the back end of the antenna are going to be really cut down.
Although they’re also very frequency specific they do cover a fairly wide chunk of radio spectrum (depending on type).
Because the television signals are (normally) strong and strictly line of sight, you can have issues with the quality of the coax as the average cable used on TV’s is well below what a dedicated scanner antenna system delivers.
CB Radio Antennas
Some scanners will happily reach down to the CB band and in this case a purpose built 27 MHz antenna will make a world of difference but how far away from the CB allocation will it still be usable?.
Not very far unfortunately as the long wavelength of a CB antenna makes performance drop off very quickly as you moved away from the CB radio bands. This wavelength is there even if using a mobile CB antenna because it’s coil loaded to make up the physical length.
FM Broadcast Band Antennas
Don’t see these mounted outside much anymore maybe because the technology has changed so much but if you’ve got one it can be a a tidy short term alternative for a scanner.
Centralized around the 88 – 108 MHZ (ish) broadcast allocation makes them suitable for low band VHF private mobile radio. Ive also had some good results on receive in the 2M (144 MHz) ham band when I found one on the roof of a place I was rented many moons ago.
These are one of the last things I would use for scanner reception as they’re made to be more directional than a TV antenna and don’t work in the traditional sense that an antenna does.
Because the actual metal part of the dish won’t be connected to your scanner there’s very little benefit in wiring up the dish.
The coax feeds straight into a LNB which then processes and relays the collected signal to the satellite receiver, meaning its coax all the way with nothing on the end but a bit of amplifier circuitry.
Giving It a Go
Modern scanners can be very forgiven as to the antenna plugged into them and there isn’t much that can do them damage.
One possible danger is a dead short in the coax cable either caused by a fault of poor installation. Running a continuity checker over the coax not only prevents problems but will also save time trying to work out why the scanner won’t received a single thing 🙂
Remember if the antennas been up for a number of years the wind, rain and sun could very well have destroyed the effectiveness of the coax.
Having some form of yardstick to determine if the antenna your using is any good does away with any doubt. Swapping back and forth between whatever antenna is being used in the house to the one outside while monitoring a “stable” transmission will soon let you know if your wasting time.
Along with using antennas outside of the frequencies they were made for there will also be mismatches with the impedance, although this is more of a problem when transmitting than receiving.
If none of the antennas live up to your expectations there are more than enough cheap purpose built scanner products out there. The only problem with mounting a scanner antenna outside is if you can’t do it yourself, the cost of installation usually ends up being a whole lot more than the antenna did in the first place.