[BC] RE: WDMN - Was: Old Arrays

[RSTYPE@aol.com]

In a message dated 6/13/2006 3:47:56 AM Eastern Standard Time, 
peterh5322 at rattlebrain.com writes:
WDMN's consultant did a good job ...

1) two sites to one, going from real estate in two states and two 
counties, to one and one,

2) twelve total towers down to five,

3) reduction in power from 1/1 kW to 0.5/0.4 kW, but using the same array 
parameters day and night, just different augmentations day and night, and

4) employed somewhat tall towers (166.9 degrees, about 300') and 
"squishing" in order to get the equivalent of very tall towers, 205 
degrees, give or take, and the corresponding higher efficiency this 
provides.

As the day and night parameters are the same, we can compute the RMS 
efficiency to be 412.23 mV/m/kW at 1 km ... significantly higher than 
Class A efficiency, and way, way higher than Class B efficiency.

Adjusting for the much higher efficiency of this array and considering 
the minimum Class B efficiency, this 0.5/0.4 kW station is equivalent to 
a 1.08/0.86 kW station, which compares favorably with its prior, higher 
power 1/1 kW operation, using conventional arrays.

A Carl E. Smith Engineers job.

Peter:

As the designer of this antenna system, I really appreciate your kind words.  
This was all made possible by the move of WDEO -  Ypsilanti, Michigan from 
1520 kHz to 990 kHz. We originally intended to utilize taller towers to simplify 
providing the high angle nighttime protection to WWKB, but were prevented 
from doing so by FAA restrictions associated with an instrument approach to 
Metcalf Airport, which is located a couple of miles to the north of the new site.  
Further improvements in the daytime facilities were precluded by the fact that 
the WDMN 0.5 mV/m daytime contour is totally encompassed by the 0.025 mV/m 
daytime contour of WQCT - Bryan, Ohio, which also operates on 1520 kHz.  
Unfortunately, reradiation and other environmental issues required different 
adjustments for the day and night patterns to permit augmentation which would meet the 
protection requirements to all stations requiring protection  consideration.  
This required the installation of a second phasor and pattern switching after 
the initial construction had been completed.

BTW, the last I knew, the old WDMN night site near the Ohio Turnpike/I-75 
interchange, which has been off the air for years, was still owned by a previous 
licensee of the station.

Roy Stype
Carl E. Smith Consulting Engineers