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Folded dipoles



Hi All,

Following this thread with great interest.

On 2M  I have been using  a 5element  X  yagi  with folded dipole driven
elements and a phasing line for RHCP.  SWR is good.

My suspisions that true RHCP is diffucult to achieve with phased dipoles
(except in the text books) is supported by  observation made over  several
months on the Amsat 2m Satellite net.   I am able to get signal reports
from 
varying distances and from  receiving stations with a variety of antennas. 
My transmissions have a noticeably stronger vertical component than
horizontal 
suggesting that my theoretical accurate system does not produce  RHCP. 

2nd Point.   The Remote Imaging Fraternity use a variety of antenna types
with
the aim of achieving omni directional RHCP weather satellite reception on
137-138MHz.
If the received signal dips in strength the deterioration in S/N ratio is
very obvious
visualy as a drop in received picture quality, even though audibly the
signal appears 
unchanged. Antennas designs that work well at one QTH seem to give  "fades"
at other QTH's.  
People with practical experience in this phenomenon  suggest  that these
fades can be 
due to strong local reflections arriving at the antenna out of phase.

73 John 
G7HIA  Net Controller Amsat-UK Midland VHF Net
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