Sometimes its just not practical to setup a full size outdoor scanner antenna or you would like to use your radio scanner when traveling. Installing a scanner antenna inside is not an ideal situation but this doesn’t mean that you cant get good results by following a few simple setup rules.
Build it High!
Receiving good signals at VHF/UHF is always a question of having the antenna up as high as possible and this if even more important when operating indoors where you already have the disadvantage of signal loss caused by the walls. Some buildings are constructed with a large amount of metal to increase its structural strength which makes using a scanner inside difficult and blocking all but the strongest of transmissions.
If you have the room then setting up a full size antenna indoors will work if you leave some room around it and make sure that no part of the antenna is bent out of shape but nearby objects, as most signals you are likely to receive are going to be vertically polarized having a antenna that has horizontal elements to it is only going to result in poor reception.
Having the antenna in an upstairs room or even fitted in the loft is going to produce much better results than just standing it next to the scanner because of the extra height.
Choice of Scanner Antenna
Discone wide band antennas with there sloping radials are ideal for mounting in a loft because of their overall small height and good performance over a huge frequency range. There are many compact wide band scanner antennas that will function indoors and have the advantage of not taken up too much space.
You can limit the size of the antenna further if your choice of listening frequencies is narrower, no point investing the time and money in a wide band antenna if you only listen to the 144MHz amateur band where a 1/2 wave mobile whip antenna will give you all the coverage you need.
Laying the Scanner Coax Cable
When running the coax from the antenna to scanner try to avoid other electronic equipment like computers, plasma screens and anything with an electric motor as these will cause so much interference to the scanner that it will almost become unusable.
If trapped in a door or regularly stepped on your scanner coax may develop a fault of completely short out altogether, this will not cause any damage to the scanner in the short term but your listening days will be over as it will stop anything being received by the scanner. Always take the time to make sure the coax is routed properly paying attention to the places where it could get damaged.
The best indoor antenna setup is one that is never going to be moved and is out of the way of other people, finding the place that will give the best reception is just a matter tuning your scanner to a constant transmission and moving the antenna to get the best signal level you can.
Please remember that excessive lengths of coax will always make any antenna system inefficient so only install as much as you need to reach from scanner to antenna.