CM Dipole with coaxial feedline. CM CM This file shows how you how you can model a coaxial feed CM To do so, use the default Nec TL card to model the feed CM and in parallel with this feed, model a wire with the CM same physical length as the feedline. The length specified CM in the TL card equals the physical lenght / the velocity CM factor for the coax. Use 'Currents->Magnitude' on the CM 'Geometry (F3)' window and use Page-up/down to magnify the CM current on the 'outer' of the coax. Click on the wire CM resembling the Coax to see how large the current is for CM the specified power input. Although the coax is fully CM symmetrical with respect to the antenna the current on CM the outer wire can cause trouble with RFI if the feedline CM is very close to a TV/telephone-line or electrical house CE wiring. SY hgh=10 ' Antenne height sy len=5.11 ' Half wire length GW 1 20 0 -len hgh 0 -0.03 hgh 1.026e-3 ' Left wire GW 2 1 0 -0.03 hgh 0 0.03 hgh 1.026e-3 ' Mid TL segment GW 3 20 0 0.03 hgh 0 len hgh 1.026e-3 ' Right wire GW 4 1 0 -0.03 1 0 0.03 1 1.026e-3 ' V-src segment GW 5 40 0 0.03 hgh 0 0.03 1 1.026e-3 ' Outer coax wire GE 0 SY Z0=50, Vf=0.66 ' Coax Z0 and Vf SY Tlen=hgh-1 ' Physical length SY Elen=Tlen/Vf ' Electrical length TL 2 1 4 1 Z0 Elen EX 6 4 1 0 1 0 GN 2 0 0 0 20 0.0303 FR 0 1 0 0 14 0 EN