Many thanks everyone.  I'm spoilt for choice. 

John F5VLF

On 6 Jul 2011, at 20:06CEST, Rick Jenkins wrote:

> Hi John,
> 
> On Wednesday, July 06, 2011 11:21:35 AM you wrote:
>> I am experimenting with various forms of matching network to go between my
>> 136kHz antenna and the transmitter. It would be very handy if I had a
>> fairly simple circuit analysis program with which to do the following:
>> 
>> Having measured the input impedance to the combined matching unit and
>> antenna, then “subtract” the components of the matching network, see what
>> I get and compare it with what I actually measure. I'm not always
>> convinced that what I measure is what I think I'm measuring.
>> 
>> Platforms available: XP, Linux and MacOs X.
>> 
>> Yes, I could write something, but somebody must have done this and there is
>> no point in reinventing the wheel.
>> 
>> Any suggestions, please?
> 
> Faced with the need to do math, I usually turn to Maxima. This is a 
> descendant 
> of the original DOD Macsyma, now with an open-source license. I run it on 
> Linux, but I am told the W*ndows version is good too. 
> 
> With a little fiddling I can usually carry through a symbolic s-plane 
> analysis 
> of a network with not too much trouble, then substitute s=jw, then throw in 
> numerical values and plot the results. There is a visual interface called 
> wxmaxima, and plotting is best done via gnuplot. 
> 
> It takes a while to do your first analysis, but as you use the system you 
> slowly come to understand its philosophy, and life gets faster and slicker. I 
> find this *much* more accurate than fiddling about with pencil and paper. 
> Maxima 
> never drops a sign or a 2*pi.
> 
> Hope this helps,
> -- 
> Rick Jenkins <[email protected]>
> Hartman Technica           http://www.hartmantech.com 
> Phone +1 (403) 230-1987
> 221 35 Avenue. N.E., Calgary, Alberta, Canada T2E 2K5
>