RE: NEC-LIST: Small antennas: can they me multiply resonant?

Chip

You say you have made measurements with 'acceptable' precision. I assume
the precision is acceptable to you, but you would benefit if it's also
acceptable to potential customers. Maybe it is, maybe it isn't. What I
said is not a personal opinion, it is what any antenna engineer would tell
you. You would not expect to buy a pound of apples measured on scales with
untraceable calibration, antenna measurements are done to the same standards
in the real world.

73s

Alan

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Subject: Fwd: NEC-LIST: Small antennas: can they me multiply resonant?

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Subject: Re: NEC-LIST: Small antennas: can they me multiply resonant?
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In a message dated 1/8/2003 7:31:38 AM Pacific Standard Time,
alan.boswell_at_baesystems.com writes:

>
> Chip
>
> I have not seen any gain measurements for fractal antennas so cannot
> comment
> on validity or otherwise. But I would characterise a traceable
measurement
> as one in which the quantities are measured with instruments whose
> calibration is traceable to an international standard by an established
> quality control procedure.
>
> In professional antenna engineering the strategy is to feed a measured
> amount of rf power to the antenna and to measure the radiated field (power
> density) at a set of points around the antenna, sufficient to calculate
the
> total radiated power. Then the gain is equal to the directivity (i.e. the
> pattern gain) less the efficiency factor, and the efficiency is the
> radiated
> power divided by the power accepted at the terminals. Gain can be
measured
> within about 0.5dB above 1GHz and about 1-2dB below 30MHz by this
approach.
>
>
> Antenna measurements techniques are summarised in "IEEE standard test
> procedures for antennas", ANSI/IEEE Std 149-1979, and the terms used
> internationally are defined in "IEEE standard definitions of terms for
> antennas", IEEE Std 145-1993.
>
> Anyone offering a new antenna for general acceptance has a good chance of
> success if the gain and efficiency are measured to professional standards.
> I don't know if this has been done for fractal antennas in particular so
> maybe you could point me to some references.
>
> All the best,
>
> Alan
>
>
>

That's a wonderful process, and I am familiar with the metrology. But
frankly, I don't care about what you call 'traceable' methodology.

With acceptable precision, the measurements I make from relative dipole
differentials, using S12, are more than adequate, and I have sufficient
confirmation from outside customers--who make their own measurements--that
we
see apples to apples.

I presume you would also disagree with a Wheeler cap method for efficiency
(that is, when applicable).

In any case, it is important for others to understand that what you and Doug

are discussing is not a question of validity, but whether one can only
believe a result if done at the highest priced facilities, such, as you
know, exist at BAE systems.

That's beyond my interest of discussion.

73,
Chip N1IR

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