[amsat-bb] NASA Helical Antenna Question

[Gregory Beat]

I posted the NASA upgrade article on QRZ Satellite Forum, April 28, 2018
https://forums.qrz.com/index.php?threads/nasa-upgrades-space-station-emergency-communications-ground-stations.608557/

Patrick Stoddard, WD9EWK provided additional information from 
the frequency chart at the ISS Fan Club web site.
VHF1 is 143.625 MHz FM, and 
VHF2 is 130.167 MHz FM

ISS Fan Club web site: https://www.issfanclub.com/
ISS Frequency Chart (includes telemetry downlinks, beacons):
https://www.issfanclub.com/frequencies

AMSAT members at NASA Goddard should be able to answer additional questions.

Greg, w9gb
— EOM —
===
Date: Tue, 8 May 2018 16:30:18 +1200
From: "Wendy and Terry Osborne"
To: "John Mac",  "Glenn Little WB4UIV"
Subject: Re: [amsat-bb] NASA Helical Antenna Question

Hi,
Yes, it's an 8 turn helix with a Gamma match (50 ohms to 120 ohms).
The advantages of ring reflector are in an IEEE Transactions paper 
somewhere. (about 25 years ago?).
Not sure what the VHF 1 and VHF 2 frequencies are but if they are more than 
a few MHz apart, that would explain the use of a helix
rather than a crossed yagi antenna.

The other picture (existingvhf.jpg) on the web page shows a 4 crossed yagi 
array with rotators.
73,
Terry Osborne ZL2BAC