Towertalk
[Top] [All Lists]

[Towertalk] Testing Equipment?

To: <towertalk@contesting.com>
Subject: [Towertalk] Testing Equipment?
From: ka4inm@tampabay.rr.com (Ronald KA4INM Youvan)
Date: Fri, 13 Dec 2002 16:54:35 +0000
>>>When a manufacturer tests antennas on a range, what 
>>>equipment is used?   A field strength meter?........

>>   The transmit antenna was a frequency cut dipole about 
>>6 miles away........


> Seems to me that with that set up,  the main "beam" of the
> transmit antenna would be high in the sky,  way above
> the "beam" of the rcv antenna under test.  Or do they
> assume both beams will intersect up there somehow to
> come together correctly???


   They are horizontal dipoles.

 >  Proper way to do a real,
 > out in the feild test of an antenna's radiation pattern,  would
 > be to have the rcv'ing gear up in a helicopter flying at just
 > the correct altitude to be at the correct height for the distance/
 > radiation angle calculation for the particular antenna under
 > test,  wouldn't it?

   The original question and the replies related to antenna test ranges.

   The antenna under test was at the factory, it was mounted 30 feet
in the air on a wooden trestle (on a turntable, they are also rotated
on their axis) 30 feet from the edge of a cliff with a huge drop off
to the normal ground level and it is within 1/2 mile of the Mississippi
river in Missouri, the dog house with the transmitter and the antenna
selector stuff with the antennas around it is 5 miles on the other side
of the river in Illinois.
   When antennas are mounted on the final tower and tested,
by any means, this far field testing arrangement proves to be accurate.

   Preliminary near field tests are used to ready (adjust) the
antennas for the turntable tests.

  I think I forgot to say the chart recorder that printed the results 
is a circular chart that rotated in phase with the antenna's motion.
  Yes, but how much would it cost to rent a helicopter every other 

day at the factory?  This way adjustments can be made until the 

antenna meets it original specifications with no rental or fuel 

costs.

   If I gave all of the details of my 1987 factory visit I would be
here all day and you would be there all day tomorrow reading it.
   This is the finest test site of it's kind in continental
America.
-- 
        73 (= Best Regards) de: Ron ka4inm@tampabay.rr.com
     100% Slack. since July, 1997 (still free!) SENT D&T are UTC
        Visit my HAM Web SITE at: http://www.qsl.net/ka4inm     


<Prev in Thread] Current Thread [Next in Thread>