[amsat-bb] TUning the antennas on a Cubesat

[Arthur Feller, W4ART]

Bob, doesn’t this assume a perfectly resistive load presented by the antenna?  If the antenna presents a reactive load, it will be non-linear, so a peak on the fundamental may well result in spurious emissions.  No?

73, art…..
W4ART  Arlington VA


> On 2-Oct-2017, at 04:27 PM, Robert McGwier <rwmcgwier at gmail.com> wrote:
> 
> Yes
> 
> On Thu, Sep 28, 2017 at 5:02 PM, Franklin Antonio <antonio at qti.qualcomm.com>
> wrote:
> 
>> Can't you just tune for maximum signal level received, and bypass
>> measuring SWR?
>> 
>> ________________________________________
>> From: AMSAT-BB <amsat-bb-bounces at amsat.org> on behalf of Robert Bruninga <
>> bruninga at usna.edu>
>> Sent: Thursday, September 28, 2017 1:25 PM
>> To: amsat-bb at amsat.org
>> Cc: Jin Kang
>> Subject: [amsat-bb] TUning the antennas on a Cubesat
>> 
>> Someone asked me how to tune the antennas on a cubesat without the
>> instrumentation totally becoming part of the antenna system itself?
>> 
>> 
>> 
>> I said you have to put the SWR instrument inside the cubesat as we did
>> here:   http://aprs.org/PSAT2/SWR-testing-0160x.jpg
>> 
>> 
>> 
>> But that only works on a 1.5U cubesat where and MFJ Antenna Analyzer will
>> fit!
>> 
>> 
>> 
>> The other method is to just put in a bidirectional coupler chip, and then
>> feed the forward and reflected voltage taps to the internal cubesat
>> telemetry system and then compute the SWR from these two Forward and
>> Reflected power telemetry channels.
>> 
>> 
>> 
>> Bob, WB4APR
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>> _______________________________________________
>> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
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> 
> 
> 
> -- 
> Bob McGwier
> Founder, Federated Wireless, Inc
> Founder and Technical Advisor, HawkEye 360, Inc
> Research Professor Virginia Tech
> Chief Scientist:  The Ted and Karyn Hume Center for National Security and
> Technology
> Senior Member IEEE, Facebook: N4HYBob, ARS: N4HY
> Faculty Advisor Virginia Tech Amateur Radio Assn. (K4KDJ)
> Director of AMSAT
> Member of PVRC (Roanoke-Blacksburg), TAPR,  life member of ARRL and AMSAT,
> NRVR.ORG (Rocketry)
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions expressed
> are solely those of the author, and do not reflect the official views of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
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