EQUIVALENT ELECTRICAL CIRCUIT FOR DESIGNING MEMS-CONTROLLED REFLECTARRAY PHASE SHIFTERS

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INTRODUCTION
Electronically tunable microstrip re°ectarrays are getting more and
more attraction and signi¯cance these days and are successfully being
applied in electronically scanning and beam-steering antennas [1{
3]. These recon¯gurable re°ectarrays possess the advantages of
both ¯xed beam re°ectarrays (such as small size, less weight and
low cost) and active phased arrays (e.g., beam scanning, adaptive
radiation pattern and dynamic phase control).


EQUIVALENT ELECTRICAL CIRCUIT MODEL
Geometry of the Problem
A complete schematic diagram of the phase shifter cell loaded with
MEMS switches is shown in Fig. 1. All the details of the unit cell are
given in the caption.
In the arrangement shown in Fig. 1, the transverse electromagnetic
mode (TEM) is the only one propagating mode within the operating


Methodology for the Extraction of the Equivalent
Electrical Circuit
The equivalent circuit is derived from step by step approach. First,
in the set of Fig. 1, replace the patch loaded with slot and MEMS by
a simple metallic patch having the same dimensions Wp £ Lp. Full-
wave EM simulations of this simple patch indicate that the two ¯rst
resonant modes, i.e.,