CP for WCLK to lower power

[BarryATL]

Why is WCLK lowering their power? My fuzzy memory seems recall something about RF emissions or some such nonsense. They are currently at 6000 watts and the CP is to lower to 2500 watts. At first glance I do not see any other changes other than lowering power.

If it is because of not being able to make the fence not go out into the middle of the street, aren't there better options for WCLK? Move to another tower?

Also, I found this in the CP authorization:

********* This is a Section 73.215 contour protection grant **********
******************* as requested by this applicant *******************

What does that mean?

 

[taylorengineer]

WCLK is directional at 6000 watts. They have a 3 db null towards the west-southwest(3000 wattsin that direction)and 6000 watts in the other directions.
They want to lower power so they can go back to non directional status and then optimize the antenna to put maximum power in certain directions. A sidemounted FM antenna can actually be designed to increase effective power in certain directions. All this is taken into account with a directional antenna so you can't "cheat."

 

[BarryATL]

So, does this mean WCLK will have a better signal across the metro by only feeding 2500 watts into the antenna?

Any idea on what the verbage about Section 73.215 is all about?

 

[littlejohn]

For a directional antenna, you have to actually measure it - normally at the factory on a test range, and the measured field cannot exceed the filed license parameters in >any< direction. For non-directional, you compute the contours. Computed contours are normally exceeded in the real world... that is, a directional system often reduces power by a quarter to a third from the same Non-D setup. So, they aren't likely to lose a lot.
Now, an antenna can and should be optimized to the structure on which its mounted. As long as the end product of the optimization is more circular than the starting point - and for a sidemount it pretty much always will be - one may if one wishes rotate the optimized pattern to whatever azimuth is to one's perceived advantage. Thus it is conceivable one might reduce power, become non-D, and gain coverage if one were located outside a desireable market.
The concept of contour protection is, one might space signals closer than the required distance for interference protection if there is a hill in the way. It is much easier to demonstrate this circumstance in Northeast Georgia than it is in forinstance Western Oklahoma.

 

[ssnake]

We've had this debate before regarding WREK.

Yes, you can optimize ERP in desired directions with a non-directional antenna so that your ERP in those directions exceeds what you could get an FCC license for. However, the increase is balanced out with a corresponding decrease in some other direction. For example, a normal omni pattern may be more like a starburst than a circle. If you have a rimshot, you can put up a light-bulb pattern under a non-directional license to aim the power toward a populated area.

However, I contend that this does not make sense for intown Atlanta stations from a population service standpoint. WREK now has a 100 kW maximizing directional CP. All in all, we will be sending out more power. The problem is getting an antenna designed to fill up the pattern. A panel-based antenna would do it easy, but our tower can't hold one. So, there are some practical considerations against a maximizing directional pattern.

Overall, less ERP will be going out from WCLK's ND CP.