[amsat-bb] 10m on a 20" whip.

[Bob Bruninga <bruninga@xxxxxxxx>]

Matching 29 Mhz to a 19" satellite whip:

If any RF engineers wanna Kibitz on this, feel free...

If I was to attach a 1w 10m SSB xcvr to our satellite 2m whip antennas, I
would need a matching network to both match the very short whips to 29 Mhz
and to also isolate the 10m xcvr from the existing 2m transceiver.  Here
is my approach:

I get a 2m dipole at 29.4 MHz shows the feed point impedance to be about 
2 - j1300 ohms.  Here is my approach:

First a series j1300 ohm inductor (7 uH) to cancel out the reactance (and
provide good isolation to the 2 meter side of the Diplexer.

Next an L network with a series 53 uH inductor and a shunt 530 uF
capacitor to give me a 50 ohm match to the 10m transmitter?

Thus it only takes a 530 uF and 60 uH (7 + 53 uH) inductor to do the
whole thing? (Neglecting the 2m side for now)...

Am I in the right ballpark?  If so, then the next step is to do a refined
calculation for the actual 2m satellite antennna which is a 90 deg phased
pair of 20" whips matched with 4 lengths of 1/4 transmission lines as
shown towards the end of http://web.usna.navy.mil/~bruninga/PSKsat.html

I think the easier thing to do will be to just measure it to find its
load impedance at 29 Mhz... rather than trying to calculate the
capacitance loading of the 4 quarter wave transmission lines at 29 Mhz.

Just looking for an easy way to get a PSK-31 xcvr into space..

de WB4APR@amsat.org, Bob

PCsat Design        http://web.usna.navy.mil/~bruninga/pcsat.html
CUBESAT Designs     http://web.usna.navy.mil/~bruninga/cubesat.html
APRS LIVE pages     http://web.usna.navy.mil/~bruninga/aprs.html
APRS SATELLITES     http://web.usna.navy.mil/~bruninga/astars.html
MIM/Mic-E/Mic-Lite  http://www.toad.net/~wclement/bruninga/mic-lite.html

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