[HamWAN PSDR] Improved radiation pattern software and new antennas on the way

[Rob Salsgiver]

Bart,

 

Can you send me a photo or two of the internals of one of these sector
antennas?  I’ve done some work with 2.4 but not 5.8.  I’m curious to know if
they are flat panels or if they are contoured (rounded or otherwise shaped).


 

I’m thinking along the lines of your sheet metal shields.  Depending on the
internal design, I’m wondering if we can’t apply some different approaches
here. 

 

The potential downside of a sheet metal shield is parasitic reflections,
unless they are spaced such that they enhance the signal (ala a reflector)
as well as shield from adjacent RF.

 

Using it as a reflector then gets me thinking of applying some other
geometries – how about a yagi or log periodic design for 5.8?  Given the
frequencies involved, it likely would fit into a similar footprint.

 

I need to do some calcs and brainstorming.  There’s definitely advantages to
having off the shelf equipment, and if possible it would be good to launch
with standard items if they work, but there may be longer-term advantages to
using some of the benefits of our “amateur” roots if we can get them to be
stable and reliable.

 

Cheers,

Rob

 

 

From: PSDR [mailto:psdr-bounces at hamwan.org] On Behalf Of Bart Kus
Sent: Wednesday, February 06, 2013 9:45 PM
To: psdr at hamwan.org
Subject: [HamWAN PSDR] Improved radiation pattern software and new antennas
on the way

 

Hello,

I've taken some time tonight to improve the radiation pattern measurement
software.  The algorithm for auto-centering the rotation of the pattern
won't be fooled now by the presence of a non-centered peak lobe.  Full
description of the software function and the software itself have both been
published to the Antenna Analysis
<https://www.hamwan.org/t/tiki-index.php?page=Antenna+Analysis&structure=Ham
WAN>  labs page.  The radiation pattern for the Laid sector
<https://www.hamwan.org/t/tiki-index.php?page=Laird+SAH58-120-16-WB&structur
e=HamWAN>  has been updated and you can see the wonky alignment is now gone!

Since neither of these antennas are thrilling performers in the HamWAN Labs
tests, a couple more candidates have been added to the Sector Antenna -
120deg
<https://www.hamwan.org/t/tiki-index.php?page=Sector+Antenna+-+120deg&struct
ure=HamWAN>  component engineering page.  A HamWAN community member who
wishes to remain anonymous has generously purchased sample antennas of the
Teletronics and RF Elements brands for lab testing.  They should arrive some
time next week.

In the meantime, I've had a thought about how to improve F/B ratios in these
sector antennas.  Using a sheet of aluminum and my sheet metal brake
<http://www.harborfreight.com/30-inch-bending-brake-67240.html> , I should
be able to manufacture traditional RF shields, like this:

VARIA 14-19dBi
variable sector antenna 45-120°, 2.4-2.5GHz

but without fancy holes or adjustable features.  It might be enough to keep
that nasty high power adjacent RF out.

--Bart

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