The many designs proposed for bandwidth improvement
[4,9] can he categorised as two general methods: broadband
matching. and using coplanar or multi-layer parasitic
elements. This classification excludes the straightforward
approach of increasing the antenna volume, for example by
increasing the substrate thickness or reducing its permittivity.
Broadband matching is usually implemented by attaching a
lossless matching network to the patch antenna. without
altering its shape. Normally, the matching network is
included in the feed part of the antenna, and it could be
realised in lumped, microstrip and coplanar technologies. It
may be integrated to some degree with the antenna hut it is
not itself a radiating element. It therefore raises the order of
the impedance response, and allows the same intrinsic
bandwidth to be used more effectively