Re(2): [Antennas] mobile ants

[cboone at earthlink.net]

Depends....a 1/4wave, yes...but not all stations use a 1/4wave...some are shorter, some longer; depends on their operating class, the required radiation minimum at 1km and other issues; also depends on how much skywave signal they want....(a 210-215 degree tall antenna is the best for minimum skywave and best groundwave...CLOSE to a 5/8wave but not exact)...I worked at a 560kHz station whose towers were 66degrees tall.. 90degrees equals 1/4wave....thus they were SHORT for the freq...4 of them straight inline and the lead tower at night is a negative Z...feeds power back into the phasor...theorectically it does not radiate!! (and a PAIN to maintain)...
Active arrays can be fun! (I used to be an engineer at the former KLIF 1190 Dallas....that runs a 12 tower array, 6 in 2 rows, broadside radiation on its night site! The main lobe is less than 20 degrees wide)

-----Original Message-----
>From: DavidE Benedict <iam at pmug.org>
>Sent: Jan 30, 2007 7:44 PM
>To: cboone at earthlink.net
>Cc: antennas at mailman.qth.net
>Subject: Re(2): [Antennas] mobile ants
>
>As
>>someone who has done active antenna arrays (especially in AM broadcast)
>>for 30 years
>
>
>So, I always wondered about broadcast...
>Are the antenna for 1600KHz significantly shorter than for 600 KHz? Seems
>like they would be by far shorter and a great financial advantage to
>high-end broadcasters.
>
>David
>W7DBH
>