NEC-LIST: Re: NEC-LIST:Simulations of Q and the Chiu-Harrington Limit

In a message dated 11/30/02 12:59:07 PM Eastern Standard Time, srbest_at_att.net
writes:

> Hi Chip,
>
> I'm assuming that you are considering antenna designs that are
> self-resonant (series resonance - dX/dw is positive) at or below some
> small KA (KA <0.5). If so, you should be able to design an antenna
> with a lossless Q that is at least within 1.5 times the fundamental
> limit. Small antennas with Qs at these levels have been described in
> the literature.
>
> The only place to be cautious is at frequencies near an anti-resonance
> (parallel resonance - dX/dw is negative). Near an anti-resonance, the Q
> of the antenna may approach zero. For this reason, Q cannot be
> approximated from 1/BW (BW being the 1/2 power or conductance bandwidth)
> or from the reactance formula: Q = (w/2R) (dX/dw + |X|/w).
> Additionally, in the anti-resonance regions, you should cautious as to
> how you interpret the relationship between Q and the fundamental limit.

The insight that is addressed is with respect to the 'Q' vs 'KR' diagram.
That is not the same as other optimization issues I am also addressing.

If you have a design that fits on that diagram, kindly guide me to it so it
may be referenced. It is not my objective to slight the professional and
useful design efforts of colleagues. On the contrary, I get a kick out of all
new designs, not just fractal ones.

73,
Chip N1IR

-- 
The NEC-List mailing list <nec-list_at_gweep.ca>
http://www.gweep.ca/mailman/listinfo.cgi/nec-list