It goes without saying that the best radio listening is only possible where unwanted interference is at a minimum and that is certainly one of the key factors used in selecting potential sites for DX-peditions.

With the Internet now pretty much universally available it brings a huge information resource within the grasp of everyone. Three valuable resources are available to anyone looking for quiet DX listening sites.

Apart from naturally occurring interference, such as lightning, rain static, all interference is man-made. More significantly it all needs a source of power, the prime culprit being electricity. Wherever electricity is generated, transmitted or consumed you will find electrical radio interference. So if you want a quiet location you know what you need to avoid. In fact the best DX-pedition sites are in locations without any electricity – which means receivers operating off batteries!

The three rules for finding a quiet location are as follows:

Overhead high voltage lines generate interference due to corona discharge and arcing across insulators especially in foggy weather or areas prone to sea spray. Any interference generated on the lines or fed back onto the lines naturally travels along the lines, which radiate the noise like an antenna. My rule of thumb is to keep at least 5km away from 225kV and 400kV lines. These are shown on the map above. AVOID!

Many railways use electricity as their power source. Poor contact between pantographs or brushes on trains and the overhead power lines generates high levels of noise, which then is carried for miles along the lines which radiate like antennas.

It does not need much imagination to realise that most consumption takes place in urban and suburban areas.

Nowadays consumption is correlated with noise from TVs, computers, switch mode power supplies, motors, fluorescent and discharge lighting. Wherever electricity is turned into light, some is turned into radio noise, a fact that confirms that light & radio are both part of the same electromagnetic spectrum.
Even worse possibilities lurk around the corner in the form of Power Line Technology; a technology which superimposes digital signals on electricity cabling to deliver Internet services to homes & businesses. If this takes off and is deployed it is highly likely that huge areas of the country will be blanketed by a noise smog that will render MW and SW no go areas for reception of anything but the most local stations. (To find out more about PLT and to help campaign against it check out your amateur radio society (ARRL in the USA and RSGB in the UK).
An extremely good picture of consumption is the picture of the country at night taken by satellite monitoring man made light radiating skywards (night time light pollution). Urban areas have an optical signature visible from space. In fact they also have a radio noise signature which I think was first exploited by bombers in the WW II to determine that they were overhead an industrial area even though lights had been blacked out (anyone know more about this technique?).

To help you to know where to look for a quiet listening site, I recommend two maps that are available on the internet; or via the MWC reprint service if you don’t have Internet access.

Firstly the Council for the Preservation of Rural England has published national and regional maps of light pollution: http://www.cpre.org.uk/campaigns/light-pollution/light-pollution-your-area.htm

Secondly the Electricity Association has published a detailed map of the UK high voltage grid and power stations www.electricity.org.uk (select Industry Facts then UK Map)

If you live in an urban area there is unfortunately not much that can be done except to move to a more rural location or to join a DX-pedition. But if you are looking for a DX-pedition site or even a new home, I hope you find this information useful.