# Explain the RG62 thing to me, please...

• Subject: [amsat-bb] Explain the RG62 thing to me, please...
• From: "Jim Shorney" <jshorney@xxxxxxxxxxxxx>
• Date: Thu, 05 Apr 2001 23:41:31 -0500

```-----BEGIN PGP SIGNED MESSAGE-----

This has been bugging me for a while, so maybe some of you with more
book-learnin' can explain it to me.

You've got two 50-ohm antennas essentially in parallel (say, crossed
dipoles in a turnstile arrangement), but one is fed with the RG62
phasing section.  I understand that the phasing section also acts as an
impedance transformer, but I don't see how it can transform the _whole
system_ to a 50-ohm impedance.

I've seen designs that use a 1/4 wave section of 75-ohm coax from each
antenna, with a 1/4 wave phasing section of 50-ohm coax in series on
the antenna side of one of the 75-ohm sections.  This seems to make
more sense to me from the standpoint of making the whole system come
out to be 50 ohms.

What am I missing?  Does the mountng method of putting the elements in
such close proximity skew the impedance such that the RG62 does the
right stuff?  Or are we using 'bistro math' in the equations...?

TIA, es 73

- --
Jim Shorney      -->.<--Put complaints in this box
nu0c@amsat.org
Lincoln, NE, USA
EN10KA
http://incolor.inetnebr.com/jshorney/
-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQCVAwUBOs1XCkCBN4ScxcExAQHUwwP/aPa+VXRyScsKxI+h4lmuHtz4xEkjsKNp
rBnZCnkeHF0PzgLs1iJwbReU3T0sq8Hk4lgmYUdHZ8PJgnYYCdTBcvRpDfmJLZIB
nGmKDfNC8hYWuefPUhAilB+92YUy2Fte1OLRS4cmxn7RTLeDWn4PkfJ+2nQjZGmU
bdpG5Vu2E14=
=TfYP
-----END PGP SIGNATURE-----

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

```

AMSAT Home