A few months back I wrote a post with a headline in the form of a question: How will WMAL-AM survive losing its transmitter? Here was my best guess at the time:
To stay on the air, WMAL will need to find replacement acreage, somewhere that allows the signals … to cross as much of the Metro area as possible, meaning it will have to be northwest of town. For that Cumulus will need to either buy land out that way, or co-site with some other station already operating there.
The only two stations with transmitters out there are WTEM (“ESPN 980″) and WSPZ, both sports stations (on 980 and 570 respectively) and owned by Red Zebra Broadcasting (in which the main stakeholders are also those of the Washington Redskins)…
Of those, WSPZ’s site looks like it has more room. It’s in Germantown, about 22 miles from downtown Washington, more than twice the distance from downtown Washington as WMAL’s current site. I suspect the signal patterns could be “tightened” to concentrate energy toward Washington, though, and that might help. But ground conductivity — which matters hugely for AM signals — is poor in Maryland and Virginia, which is one reason AM stations there tend to suck in the ratings.
Now comes word that Cumulus plans to use the WSPZ/570 site. Here are the day and night signal applications to the FCC. The day power will be the same as at the current site: 10000 watts. But the night power will be only 2700 watts, rather than the current 5000 watts. As I expected, the signals both day and night are “tightened” to a headlight beam shining toward the District. The day signal is on the left and the night signal on the right. (Source: fccinfo.com)
WSPZ has similar day and night patterns, at 5000 and 1000 watts, using the same four towers.
Here is how Radio-Locator.com sees WSPZ’s day and night patterns. Since the two stations are close in frequency (which greatly affects propagation: lower on the dial is better), expect WMAL’s coverage to be about the same as WSPZ’s.