ABSTRACT
It is well-known that the directivity of microstrip antennas is inherently low, but it can be enhanced by using a frequency selective surface (FSS). There are two basic types of FSS structures: reflection and transmission. Reflective FSS structures are used to improve the directivity as shown in References 64-67. In References 68 and 124, the FSS exhibits transmission characteristics, and in Reference 68 the FSS is used for antenna directivity improvement.
