Just when you think you understand how things work… The FCC maintains an official list of AM and FM radio stations that have requested to remain off the air, have been granted permission and have been silent for at least 2 months. In most cases, the station is broke and either can’t pay its staff or has a repair problem with the transmitter they can’t afford to fix. The outcome is usually a station sale or the license is turned back into the FCC at the end of a year of silence.
While updating the list (and restoring the “No longer silent” stations), I ran across WAGE-AM, which filed an application with the FCC on 2/24/2011 called “Method of Moments”. I had never seen one of these before.
WAGE-AM is a 50kw daytime, 1300 watts night time station in Leesburg, Virginia – potentially a very valuable AM station. It has been off the air since July 2010, fighting with local “land use” people (aka NIMBYs) trying to block the station from upgrading its antenna. (“AM radio causes 3 headed frogs!!!”). There are a couple major syndicated radio shows that currently need a home in the Washington DC area. News Story
When a radio station is built (or when it changes its power), the engineers have to measure how strong the signal is. Before you build a tower, it’s just theory. AM especially is subject to unexpected behavior because how well an AM signal travels is based largely on the ground and what is under it. When an AM station has a directional pattern created by multiple towers and buried copper cables, it’s important to make sure the real world results match the theoretical The most direct way to do that is to take an RF meter out into the real world and measure at a number of spots inside the predicted contour and see if reality matches theory, and fix things if it doesn’t.
The somewhat scary “Method of Moments” turns out to be a computer modeling approach to prove the behavior of a directional antenna without actually measuring it in the field. Here is a company that does this:
A few months ago, I read an anecdote about how the real and theoretical world differ. Someone noticed that an AM station was sounding really strong, much more so than you would have expected. After poking around, they discovered that someone at the station had connected a ground wire from the antenna to a railroad track that ran behind their property.
Give the ‘ground wire’ employee a bonus, better yet send me his resume.