kyscott said:
I was downtown last weekend and thought I'd punch up 105.1 after seeing the billboard on I-64. Now that they have moved the transmitter and gone directional over the city, it's much harder to hear them downtown. Moving up to Mitchell hill solved the shadowing problem in the south end, however having the null over Louisville is hurting them in the northern part and up into Indiana.
That makes sense that the south end improved, which was no doubt critical for them and made it "worth it". But the cost to them in general signal coverage is worse than most people realize.
You know this, Scott, but most other people don't. When you have a normal antenna, the pattern distortion that the tower causes can be used for the advantage of the station. If you are licensed as 3 KW, and put your antenna on the side of a tower, you automatically may have 4.5 KW on the antenna side of the tower and 1.5 KW in the opposite direction. To the FCC, that all balances out overall and they are fine with it. So if you are south of the city, you put your antenna on the north side of the tower.
But the FCC also lets you "optimize" your antenna. This is a means of adding directional elements near the antenna to balance out the vertical and horizontal radiation characteristics to make them about the same. That helps a lot in the multipath. But it also can create a huge "push" in one direction.
But with a directional antenna, you aren't allowed to exceed the licensed value at all
in any direction.
The old LRS had an optimized antenna on a special tower section that is tuned to 105.1 to maximize the radiation toward Louisville. They were licensed as 3KW, but you can bet that they were radiating a full 6KW toward the city.
The new LRS is a 6KW at 100 meters equivalent. But they have a directional null of 0.58 field toward St Matthews. That's about 1600 watts. That's the best case scenario. In real life when they made the antenna, they did a pattern study and tried all kinds of things to make it as good as they could get it. They probably didn't get their 1600 watts toward St Matthews. If they are lucky, they got 1200.
Their null starts at 340 degrees, almost northwest, to 70 degrees, almost east, with the minima at 40 degrees being 0.58. They cannot exceed the licensed value at any point along the 360 degree circle. If real life makes it less than theoretical, well then it's just less. And with directional FMs, real life ALWAYS interferes with theory.
So the bottom line is this: LRS went from a 3KW station to a 6KW station, but in the process lost a legal "cheat" they had on their old antenna. They lost their terrain shading, which is the best thing that happened to them. But they went down to about 1/4 of the power they used to radiate toward Louisville. It's definitely a mixed bag.