Hi Peter I think it more due to the fact that commercial bridges and meters
really want to cover the widest range. There is obviously a problem with serial
connected reactances when one is very much larger than the other. Then the
nulls on bridges become shallow and ill defined. If you use a parallel
arrangement this is not a problem. For most Amateur aerial cases you can get
away with serial connection because there is not the need for the wide range
needed for laboratory equipment.....10^3 compared with maybe 10^6.
Alan G3NYK
--- On Wed, 19/11/08, Peter Dodd <g3ldo@ukonline.co.uk> wrote:
> From: Peter Dodd <g3ldo@ukonline.co.uk>
> Subject: LF: More on Admittance
> To: rsgb_lf_group@blacksheep.org
> Date: Wednesday, 19 November, 2008, 6:55 PM
> Many thanks to those who responded to my question regarding
> an
> Admittance to Impedance converter.
> I have a further question. Since most of the measurements
> we make on
> antennas and transmission line require the answer in term
> of impedance
> why are there so many commercial instruments calibrated in
> units of
> Admittance, particularly at VHF and UHF. I suspect that it
> is because it
> is easier to make accurate variable bridge standards if
> they use a
> parallel arrangement; is this true
> Regards
>
> Peter, G3LDO
>
>
> > The best program (as far as I am concerned) is called
> Z-Y Converter,
> > which was sent to me by Rik Strobbe.
> > It came direct because it gave the reflector
> indigestion although it
> > is only 160KB.
> > I was given a General Radio 1602-B Admittance Meter as
> a pre Christmas
> > present, which is calibrated in millimhos, which I
> guess is the same
> > as millisiemens.
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