Dispersion and series gap discontinuity of shielded suspended striplines (SSL’s) on Duroid substrate (εr = 2.22) are analyzed using the finite-difference time-domain method (FD-TD). Numerical accuracy of better than 0.15% is achieved when the FD-TD is used to calculate the effective dielectric constant (εreff) of an air-filled rectangular coaxial transmission line. Data obtained for the frequency-dependent εreff of uniform SSL’s, and both scattering and equivalent circuit parameters of various series gap discontinuities, are then presented. In general, presence of sidewall mounting grooves causes a nearly frequency-independent small reduction in εreff On the other hand, proximity effects of the housing are found to be more important. It is demonstrated that: 1) for a given housing, εreff decreases first with an increase in strip width before increasing again when strip is wider enough to interact strongly with the sidewalls and 2) reducing sidewall spacing causes an increase in εreffFor the gap discontinuity, coupling across the gap is stronger for wider strips and/or narrower gap width. Irregular transmission behavior is also found when strip is wide enough to interact strongly with the sidewalls.
|Number of pages||6|
|Journal||IEEE Transactions on Microwave Theory and Techniques|
|State||Published - 1 Jan 1992|