Dear Mike, LF group,
...I am writing a short chapter on using
computers in amateur radio, for
the new edition of the RSGB's Radio
Communication Handbook.
This is about construction and not
operating, and I am interested in
what software is used by group members when
designing building and
testing amateur radio equipment, including
antennas and not just for
LF...
Spectrogram programmes, such as
Spectrum Lab, are useful for very many things apart from LF reception, such as
measuring distortion, intermodulation, noise, oscillator drift, modulation, and
propagation study (see, for example, the CDG2000 transceiver articles from RadCom
a while ago, the various LF propagation web pages). The performance of
spectrogram software plus soundcard as an audio spectrum analyser is hard to
beat, provided you don't mind supplying your own amplitude calibration.
There are quite a few NEC-based programmes around for
antenna analysis, some available in free demo versions - see for example: http://www.cebik.com/model/nec.html
I suspect that amateur antenna designers have become a
bit over-reliant on NEC, and tend to neglect the “real world”
aspects of antenna behaviour as a result, but it certainly does provide a useful
facility, all the same.
There are also many SPICE-based
simulator programmes around - see http://www.terrypin.dial.pipex.com/ECADList.html
, for example. Some of these are available as free demos (as rather large
downloads), usually with restrictions on the free version. These things are
very useful to see if or how a circuit "works", and can usually quite
accurately predict performance (mostly for analogue circuits), although they do
require substantial effort to learn to use effectively. I have used PSpice a
lot when designing amateur radio circuits, mostly because I can “borrow”
it from work. A circuit simulator won’t do the designing for you, but it
does help a lot in finding out what is wrong with a design, and predicting what
will happen before you actually build the circuit.
I would echo what people have
already said about G4FGQ’s software utilities, and the AADE filter design
software – these programmes have saved me a lot of time pushing buttons
on a calculator in the past!
Cheers, Jim Moritz
73 de M0BMU
