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Registered User · December 12th 10, 02:01 PM posted to rec.radio.amateur.antenna

On Sun, 12 Dec 2010 06:26:29 -0000, wrote:

joe wrote:
Art Unwin wrote:

Think about it Joe
If you had an equation for efficiency it would be dimensionless.

It depends upon how efficiency is measured. My more efficient car gets
30 MPG, My less efficient car gets 15 MPG. Any equation defining
efficiency in terms of miles per gallon does not have a dimensionless
result.

That isn't "efficiency", which is what is applies to antennas and it is
ALWAY a dimenionless number.

Efficiency is a measure so it must have one or more dimensions to have
relative meaning. The subject doesn't really matter. If Nigel Tufnel
says his antenna has an efficiency of 11 what does the number
represent beyond being one more efficient than ten? One more what?
Without any metadata the value is just a number, it just as well could
be 3.14159265 or 0xBADF00D.

A measure such as SWR might appear to be dimension-less because it is
a calculated value based upon dimensional values.

What you are talking about is "fuel efficiency", a different thing entirely.

It's not really different, units consumed is a measure and units
traveled is a dimension. An attribute of the dimension is city or
highway driving. By adding metadata in the form of additional
dimensions, attributes and hierarchies more meaning can be given to
the measure.

The efficiency of a car is the useful energy output divided by the energy
in the fuel.

Limited dimensions suggest that 4 passenger vehicle's 40 MPG is more
fuel efficient than a 40 passenger bus getting 8 MPG. Add the
dimension of passengers carried, change the measure to passenger*miles
per gallon, and the bus (320 PMPG) becomes more fuel efficient than
the car (160 PMPG). More metadata provides more meaning to measures
which in turn provides better foundation information for effective
decision making.

In every case dimensions add meaning to the measure. The whole issue
with Art's magic antennas is he values their efficiency by presenting
measures that have no relative dimensions. The efficiency of his
antennas may well be 11. The question remains eleven what?