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From: Dan Handelsman, N2DT
Date: 17 Apr 2002
Time: 14:46:06
Remote Name: 168.100.201.177
Bill,
Two points I would like to make.
1 - I don't know if you caught it but I waded into this discussion last week - somewhere below here - to put in my two cents about NEC being able to model some aspects of your dielectric loading problem.
2 - in reference to the reply I made just below to DJ's question on patch antennas, one point that Bob Haviland brought out in his article is the effect of dielectric on the wavelength of a EM wave. The wavelength is changed when compared to air and this results in a lower VF. But also, when you look at closely spaced metallic plates or shielding sorrounding an axial center conductor, the effective separation is decreased as compared to an air dielectric.
Or to put it another way, an effective .01 wl separation results from a dielectric in a distance less than .01 wl in air. So the effect on coaxial lines is not at all surprising.