[BC] Franklin Antenna - KTTO (ex-KREM)]

[Peter]

On Sep 13, 2008, at 1:22 PM, Peter wrote:

>
>> I have heard that an asymetrical Franklin is called a Jeffers  
>> Antenna.
>
> Interesting.
>
> Every example I have seen has been signed by A.D. Ring &  
> Associates. Perhaps Jeffers was a Ring employee.

I'll correct myself, and amplify this subject somewhat.

"An Antenna for Controlling the Nonfading Range of Broadcast  
Stations", Charles L. Jeffers, Proc. IRE, Waves and Electrons  
Section, Nov. 1948, pp. 1426-1431.

Jeffers credits A.D. Ring for "a helpful comment" in  the development  
of this type of antenna. Jeffers was apparently an employee of Radio  
Station WOAI. At least he is so listed in the cited article.

Although the cited article was for a 180 degree over 120 degree  
antenna (WHO used this type), and the cited station was indeed WOAI,  
WOAI actually implemented a 120 degree over 120 degree radiator (two,  
at different sites), not a 180 degree over 120 degree radiator as was  
stated in the article. Apparently, all the modeling was done for 180  
over 120, but the actual implementation was 120 over 120, at two  
sites at different times.

It may well be that the ideal configuration is a function of frequency.

180 over 120 is being used successfully at 1040 kHz. About 470 mV/m/ 
kW at 1 km.

120 over 120 was used successfully at 1200 kHz (two sites, abandoned  
for a 195 at a third site). About 420 mV/m/kW at 1 km.

179 over 179 is being used successfully at 1500 kHz (days only).  
About 510 mV/m/kW at 1 km.

180 over 180 is being used successfully at 1530 kHz (days and nights,  
in a two-tower DA-2 configuration, with both towers being 180 over  
180). About 510 mV/m/kW at 1 km.

The "reference standard" for Class As is 195 degrees as the average  
height over all ND-U Class As in the U.S. is 195. About 400 mV/m/kW  
at 1 km.

I guess in the last analysis the difference between 195 and 240 (120  
over 120) wasn't worth the extra 45 degrees.

So, yes, the term "Jeffers" could be attributed to an asymmetrical  
sectional with no top loading of either section. (A symmetrical  
sectional with no top loading of either section, other than 360  
degrees total height, too).

Jeffers provided analytical solutions for this type of radiator. An  
analytical solution (never a table-driven solution) is an absolute  
requirement for inclusion in the FCC's programs, yet the FCC has not  
done so, not withstanding the facts that these types of radiators  
have been used since at least the end of WW-II, if not earlier, and  
more than a handful are still in use.

Peter