Re: [IRCA] Short antenna radials

["Mark Durenberger" <Mark4@xxxxxxxxxxxxxxx>]

To add to Dennis' info:  The KSTP antenna was/is a 179.4/179.4 and appears 
to be considered a "Sectional" rather than a Franklin by the FCC. 
Nit-picking' I guess.

Happy Holidays!

Regards,

Mark Durenberger


-----Original Message----- 
From: Dennis Gibson
Sent: Saturday, November 30, 2013 10:26 PM
To: irca@xxxxxxxxxxxxxxxx
Subject: Re: [IRCA] Short antenna radials

KFI's original tower was there before the industrial complex was built. The 
new tower was built at the same place as the old and uses the same ground 
radials.

KFBK and the KSTP day site both use Franklin antennas, the only two in the 
country. A Franklin antenna consists of two 180 degree electrical height 
(one half wavelength) antennas separated by an insulator, stacked vertically 
and fed at the center. The top half radiates and the bottom half is the 
ground. There are no ground radials.

Date: Sat, 30 Nov 2013 13:50:34 -0800 (PST)
From: Stephen Airy <pianoplayer88key@xxxxxxxxx>
To: w7swl@xxxxxxxxx, irca@xxxxxxxxxxxxxxxx
Subject: Re: [IRCA] Short antenna radials

I've been recently wondering about this myself (short-radial efficiency, or 
lack thereof), but more from the standpoint of low-power part 15 
transmitting setups.  One example I'm thinking of is such that the total 
length of the antenna AND all ground radials is 3 meters, and does it make 
much difference if you use a base-fed radiator with radials vs a center-fed 
segmented short dipole without radials. (The rule in 15.219 specifies the 
antenna, transmission line, and ground lead cannot exceed 3 meters.) 
There's other scenarios I'm wondering about, but I'll leave them off as I 
think it's beyond the scope of this list.

As for KFI, I believe the original tower was there long before the 
industrial complex was built. So, I think there could be ground radials 
there already, and the new tower was hooked up to them?  Or maybe they have 
another way of grounding it. KFI *is* a few dB weaker at my house than KNX, 
in spite of being 12 miles closer (99 vs 111).  I think it's primarily the 
partial saltwater path for KNX in my case, though.  At a friend's house in 
Moreno Valley, as well as at my grandma's house in San Gabriel, KFI is 
considerably stronger, like 10-15 dB.

There is a very efficient station that I believe doesn't have ground 
radials - 1530 KFBK in Sacramento, CA.  Also I suspect 1500 KSTP St Paul, 
MN's daytime site may also not have ground radials, but I'm not totally 
positive on that one.

73, Stephen

Sent from my iPad
_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the 
original contributors and do not necessarily reflect the opinion of the 
IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx 

_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx