BW Enhancement Using air substrates

One way of improving the bandwidth to 10-20% is to use parasitic patches, either in another layer (stacked geometry) or in the same layer (coplanar geometry). However, the stacked geometry has the disadvantage of increasing the thickness of the antenna while the coplanar geometry has the disadvantage of increasing the lateral size of the antenna. It would therefore be of considerable interest if a single-layer single-patch wideband microstrip antenna could be developed. Such an antenna would better preserve the thin profile characteristics and would not introduce grating lobe problems when used in an array environment.

Fig: Using air or foam substrates