"Tom Donaly" wrote in
:

....
Why would NEC reduce a TL two-port to a lumped load? Two-port
parameters can handle transmission line problems quite well without
the simplifying assumption that all components are of zero length.

Hi Tom,

I expect that NEC does model the propagation delay from end to end on a
transmission line. My comment was that NEC reduces a s/c TL stub to a
lumped load for the stub input end which is inserted in the vertical.

The problem here perhaps is our viewing the phasing section as a s/c stub
of two wire line, when perhaps is it better described as a single wire TL
of a half wave length.

With that thought in mind, I have constructed a model where the phasing
section is configured in a double triangular shape, but with the same
conductor length, and NEC suggests in-phase currents. In fact, it has
slightly better pattern symmetry than a).

CM
CE
GW 1 15 0 0 0 0 0 5 0.0005
GW 5 30 0 0 5.1 0 0 15 0.0005
GW 10 7 0 0 5 1.47 0 5. 0.0005
GW 11 10 1.47 0 5. 0 1.47 5. 0.0005
GW 12 15 0 1.47 5. 0 -1.47 5.1 0.0005
GW 13 7 0 -1.47 5.1 -1.47 0 5.1 0.0005
GW 14 15 -1.47 0 5.1 0 0 5.1 0.0005
GE 1
GN 1
EK
EX 0 1 1 0 1.0 0
FR 0 0 0 0 15 0
EN

Owen