Re: NEC-LIST: Near-field coupling of antennas

Todd Nichols <nichols_at_rtp.ericsson.se> wrote:
>Does anyone have a suggestion for the most straightforward way of
>determining the coupling (or isolation) between two antennas on a
>metallic structure? I have a wire-grid model of the system, but
>the antennas are close enough together that near-field effects
>cannot be ignored.

I think that what you want is easily done. NEC-2's solution of the field
equations does not neglect near-field effects. Only the radiation-pattern
calculation is far-field only. So, if you want to know the coupling
between any two "ports", e.g., their mutual impedance, just excite one port
(the feed-point of one antenna) with a source (voltage or current) and
observe the current and/or voltage at the other port (the feed-point of the
second antenna) by connecting the appropriate load (e.g., zero or 50 or
near-infinity ohms, or whatever) to the appropriate port and NEC-2 will
tell you the load voltage & current. Of course, NEC-2 can tell you the
currents _everywhere_ if you want.

-Chuck.
Received on Thu Jul 17 1997 - 10:53:37 EDT