[BC] Short AM Tower

[Tom]

Cite :

http://www.courts.state.nh.us/supreme/opinions/2002/0212/koor152.htm

And put up a 190 foot, 18" face tower, with standard ground radials, 
etc. NEC-2 modeling gives a nominal base impedance of ~ 37.49 + j3 
ohms.  Tell local officialdom that FCC trumps local ordinances inre: 
transmitting antennas, and the size thereof.

Here in Indy, "local ordinance" generally prohibits towers over 75 
feet... Yet there are several towers built since then for FM and 
commercial repeater use WELL over 75 feet.  Including the 300 meter one 
on National Avenue (about 4 blocks from my church) that has 106.7 on 
top, and the backup for 96.3 at the 2/3 level.

So!

Tom S.

R A Meuser wrote:
> About 30 feet of top loading and a fat tower (2 to 3 foot face) will 
> get the drive point impedance to a reasonable value. I would also 
> agree with those who suggest a series fed radiator. The simplicity 
> will help keep the station with a good signal after the engineers 
> leave. It would be worth getting this all properly modeled first to 
> optimize the tower size and loading.
>
>
>
> Richard Fry wrote:
>> Larry Lamoray wrote:
>>
>>> Have a client trying to use a 100 ft tower for AM on 1230.
>>> 200 feet is prohibited by local ordinance. :-((
>>> Any suggestions as to how to make the best of a bad situation?
>>
>> ______________
>>
>> A quick look with NEC hints that a 100' monopole with 2' faces used 
>> with 120 radials each at least 1/4-wave long could just make 241 mV/m 
>> at 1 km for 1 kW of applied power if the total of the r-f ground and 
>> matching loss was ~ 4 ohms.  The SWR bandwidth when optimized for 
>> 1230 kHz shows to be less than 1.3:1 at +/- 10 kHz.