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15
Planar Transmission Lines
15.1 Introduction
A class of transmission lines referred to as planar transmission lines is used
over a very wide frequency range starting from centimetric to the submil-
limetric zone to guide the electromagnetic waves. These have the same
characterising parameters (viz. Z
0
,
γ
,
α
,
β
, c,
υ
p
and
υ
g
) as applicable to other
transmission structures. Their geometry allows the control of these param-
eters, particularly the characteristic impedance by dening dimensions in a
single plane. This feature allows a complete transmission line circuit to be
fabricated in one step by using thin lm and photolithography tech ...