ABSTRACT
Miniaturization and de-miniaturization of an antenna are both required for practical applications. Use of higher permittivity DRA can significantly reduce the size of DRA, and use of low permittivity material can increase the size of DRA. Manipulation of resonant modes can also help us to reduce and increase the size of DRA. Use of metallic strips further decreases the size of DRA. Defected ground plane structure is one more technique that can be used for miniaturization. Applying metallic strips based on image effect is another technique to reduce dimensions. Specific structure of DRA can also miniaturize the size of an antenna. A metallic patch is used to miniaturize the size of rectangular DRA. DRA at higher frequencies in the range of terahertz need smaller dimensions. Fundamental and higher order modes can be excited into single DRA. Designing of DRA for fundamental mode and operating the same at higher order mode need larger dimensions. The fabrication of DRA with bigger dimensions seems to be an easy task. De-miniaturization of DRA can be achieved this way. Similarly, the opposite is also true; that shall be called miniaturization. In this chapter, de-miniaturization and miniaturization techniques of DRAs have been studied. Shifting of fundamental mode in DRA to the lower side will miniaturize the DRA. This can be achieved by using metal strips on DRA.
