Hi Rune
I'm quite late on these comments; however I would like to recommend some
reading on recent new phased arrays.
Dr Dallas is working hard to improve his Quad Delta Flag, he is focus on
maximum F/B, for ham use we can change the phase for maximum RDF. Increasing
F/B reduces the RDF and wide the front lobe, just keep the phase close to
180 degree, like 180 front and 175 in the back flag, this will give you a
good RDF and a decent F/B.
http://www.kongsfjord.no/dl/dl.htm
As Gary just mentioned, interaction with TX antenna is could be very deep
for all kind of receiver antennas. The issue is not to change the impedance
on the TX coax line, it is to remove the 1/2 wave length wire or structure
interacting with the RX antenna and re-radiating signals and noise back into
the receiver antenna, like elevated radials must be disconnected in 1/4 wave
parts, any wire close to 1/2 wave in the air or 1/4 connected to the ground
will reradiate signals and noise into the RX antenna.
Second most common problem is common mode noise; you won't like to phase the
signal from your receiver antenna with the signal coming from the coax
shield, BUT... and here is the but... if you don't choke properly the common
mode current will add in you phased signal.
Small phase arrays can delivery a fantastic performance if well implemented.
Here one excellent example of small lot high performance RX antenna.
http://www.kongsfjord.no/dl/Antennas/Phased%20Delta%20Flag%20Arrays%20rev%20
6.pdf
Regards
Carlos
N4IS
-----Original Message-----
From: topband-bounces@contesting.com [mailto:topband-bounces@contesting.com]
On Behalf Of La7tha
Sent: Wednesday, August 12, 2009 6:27 AM
To: topband@contesting.com
Subject: Topband: InfoK9AY Phased array and EWE posible problem.
Hi all
Thanks to all that have send me info about K9AY Phased array.
At the same time i will ask for a EWE possible problem.
I mounted a EWE antenna last summer, but could not get it to work.
after some Google etc i have found that the EWE antenna are very critical to
ground.
Some Hams mention that they use a ground wire under the antenna.
Is this wire just put on the ground, or is it connected to the feed point
ground and also @ the far end (reistor end) ground.
Any suggestion on this one.
73 de Rune LA7THA
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.392 / Virus Database: 270.13.52/2298 - Release Date: 08/12/09
06:09:00
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|