[amsat-bb] Re: Antenna Analyzer

i8cvs domenico.i8cvs at tin.it
Sun Mar 6 19:56:33 PST 2011

Hi Art, KC6UQH

If you are satisfied with an antenna  VSWR in the order of 1.5 : 1 then
you don't need an antenna analyser but only a VSWR meter.

An antenna analyser must be able to measure with accuracy the real part and
the imaginary part of the impedance i.e. the resistive and the reactive part
of the impedance Z = R +/- jX

For example the same antenna VSWR of 1.5 : 1 can be obtained with an
antenna impedance having the following values and all of them are laying
over the same VSWR circle of the Smith Chart

Z1 = 38+j13 ohm
Z2 = 66+j16 ohm
Z3 = 58- j20 ohm
Z4 = 34- j0   ohm

Since the same VSWR can be found over a VSWR circle then the values
of the impedance giving the same VSWR are infinite values.

The MFJ-269 analyser make acceptable  R +/-jX measurements only up to
30 MHz but fail to measure accurate resistive and reactive part of the
impedance above 30 MHz and in other words it is not a respectable antenna

Why to wast money to buy an antenna analyser to measure wrong values of
Z= R+/- jX if been happy with only the value of the VSWR you need only a
VSWR meter ?

73" de

i8CVS Domenico

> ----- Original Message -----
> From: "Art McBride" <kc6uqh at cox.net>
> To: "'i8cvs'" <domenico.i8cvs at tin.it>; "'Pete Rowe'" <ptrowe at yahoo.com>;
> "'AMSAT BB'" <amsat-bb at amsat.org>; "'Howard Kowall'" <hkowall at shaw.ca>
> Sent: Sunday, March 06, 2011 7:38 PM
> Subject: RE: [amsat-bb] Re: Antenna Analyzer
> Domenico,
> For most Amateur Radio work a VSWR of 1.5:1 is adequate. I personally have
> never expected MFJ products to be in the League of Anristu, HP and Rohde
> and  Swartz.
> MFJ is a yard stick, the others are a micrometers
> Art,
> -----Original Message-----
> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
> Behalf Of i8cvs
> Sent: Sunday, March 06, 2011 9:41 AM
> To: Pete Rowe; AMSAT BB; Howard Kowall
> Subject: [amsat-bb] Re: Antenna Analyzer
> Hi Pete, WA6WOA
> I do not recommend the MFJ-269 antenna analyser because it is very
> inaccurate particularly on 435 MHz
> I have compared the MFJ-269 with several professional network analysers
> and  I have found that at most the MFJ is usable up to 30 MHz maximum
> because above 30 MHz the inaccuracy on the real part and the imaginary
> part of the impedance reading becomes absolutely unacceptable.
> My MFJ-269 was purchased as new but connecting to it a professional
> 50 ohm termination good up to 12 GHz the VSWR shown at 435 MHz
> was 1.1
> I have sent back my MFJ to the factory for inspecting  and calibration but
> I belive that the above instrument was a very bad affair for me and will
> be a bad affair for all that intend to use the analyser above 30 MHz.
> Be happy with your MFJ-269 even if  dreaming while sleeping I am sure that
> my message made you suspect a wrong real part and a wrong imaginary part
> on your impedance reading !
> Best 73" de
> i8CVS Domenico
> ----- Original Message -----
> > From: "Pete Rowe" <ptrowe at yahoo.com>
> > To: "AMSAT BB" <amsat-bb at amsat.org>; "Howard Kowall" <hkowall at shaw.ca>
> > Sent: Sunday, March 06, 2011 4:45 PM
> > Subject: [amsat-bb] Re: Antenna Analyzer
> >
> >
> > Hi Howard
> > I wouldn't be without my MFJ-269 analyzer. It is very accurate and a
> > handy size. Highly recommended. (no, I don't own stock in MFJ)
> > One word of caution: mine (and maybe there is something wrong with mine)
> > draws some power from the batteries with the power switch OFF. So I take
> > one of the batteries out when not in use.
> >
> > 73,
> > Pete
> > WA6WOA
> >
> > --- On Sun, 3/6/11, Howard Kowall <hkowall at shaw.ca> wrote:
> >
> > From: Howard Kowall <hkowall at shaw.ca>
> > Subject: [amsat-bb]  Antenna Analyzer
> > To: "AMSAT BB" <amsat-bb at amsat.org>
> > Date: Sunday, March 6, 2011, 6:16 AM
> >
> > Hello to everyone
> > I am seriously thinking about buying an antenna analyzer,I build enough
> > antennas to justify buying one.I enjoy building HF,VHF,UHF antennas of
> > all flavors.The standard swr bridge is just not cutting it anymore.So I
> > guess what I am looking for is one that will do 3mhz to 500mhz,nice to
> > have computer interface but not a priority.I have seen a few on the
> > internet but its nice to get some user input,rather then the sales
> > pitches.
> > Thanks to all who read and reply in advance
> > Howard
> > VE4ISP
> > _______________________________________________
> > Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT-NA member? Join now to support the amateur satellite
> > program!
> > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list