NEC-LIST: NEC applicable to CFA?

Dear Jack,

    I am sending to you by US Mail a copy of US Patent 5,155,495 by
Hately, et al.

    According to my understanding, the inventor maintains that
radiated power depends upon the E and H fields notwithstanding how E
and H are generated. Distributed current flow in a wire is a special
case but certainly we can both visualize how E and H fields can be
generated by other means. In keeping with that thesis, I especially
invite your attention to lines 58-60 of column #1 in the patent under
the heading 'THE INVENTION'. I interpret that statement to be a
declaration by the inventor that the disclosed antenna generates the E
and H fields by means other than a distributed current flow in a wire.

    I am by no means qualified as an expert on NEC so please forgive
my boldness that follows. I understand NEC to be a special
application of the method of moments wherein the moment being
considered is a current moment. In support thereof, I refer to the
electric field integral equation used by NEC whose form follows from
an integral representation for the electric field of a volume current
distribution. Moreover, the magnetic field integral equation used by
NEC is derived from the integral representation for the magnetic field
of a surface current distribution. From that I conclude that NEC
arrives at E and H fields (and hence radiated power) starting with the
analysis of currents.

    My question as to whether or not NEC is the appropriate means to
analyze the CFA stems from the difference mentioned above. NEC
determines radiation by applying the E and H fields generated by a
distributed current flow. The inventor of the CFA claims radiation
due to E and H fields generated by means other than a distributed
current flow. There appears to be no obvious correspondence between
the NEC calculated E and H fields and the fields of the CFA so perhaps
we should not expect a correspondence between the calculated radiated
power, impedance values, etc.

    I can readily agree that NEC will analyze any antenna that depends
upon a distributed current flow to generate the E and H fields. On
the other hand, perhaps the CFA is a different breed and requires a
different approach to analysis.

    Jack, I am very interested in your response and I'm sure others
are also. Please continue to share your analysis with us on the
NEC-LIST.

With personal regards,

J.L. Smith
jlsmith_at_datasync.com
Received on Wed Apr 14 1999 - 22:42:59 EDT