Re: NEC-LIST: Quadrifilar Helix Modelling on NEC

From: Max J. Schmitt <mjschmit_at_email.domain.hidden>
Date: Sat, 24 Jun 2000 13:17:14 -0400

Joe Noci wrote:

> As a hobby I chase the orbiting WXsats around the skies and am always
> trying out different receive antennae.
>
> I have been modelling the QFH and have concluded that there is more to
> learn than meets the eye....

Hello Joe,

Two years ago, I designed a dielectric-loaded helix antenna for 1800
MHz for satellite communications. I used NEC - WIN Pro and got good
results, i.e., antenna patterns, gain, impedance, VSWR, etc. Of
course, this was for a stationary satellite. I guess your WXsats are
weather satellites, because of the 137 MHz frequency, so the
satellites are low polar orbit ? I am familiar with quad helix
antennas, and should be relatively simple to model those. However, I
believe you should calculate the design and model only check your
design. Also, I guess, a regular high gain helix antenna, or a helix
array should give you sufficient gain to get satisfactory
reception. If you can tell me your gain requirements, I probably could
give you advice with the basic equations. Of course, many antenna
design books contain those basic formulations. I would try,e.g.,
Antenna Theory by Constantine A. Balanis .

Best regards,

Max Schmitt
Cons.Eng.
Received on Tue Jun 27 2000 - 14:14:05 EDT

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