Today with regard to the needing for miniaturized communication block have been raised small antennas applications. Microstrip patch antennas are suitable candidates for such applications. But size of these antennas is large in low frequencies. Several methods have been proposed for the miniaturization of antennas in some references, which have some shortcomings, such as reduction of impedance band widths. Realization of both good, impedance bandwidth and small antenna size is difficult and are almost contradictory. That is, improvement of one, deteriorates the other. Moreover, reduction of antenna size caused to perturbation in radiation pattern and reduction of gain and radiation efficiency. In this work, present some of novel methods for reduction of antenna size and increasing bandwidth; as minimum perturbation in radiation pattern, efficiency and gain of antenna occur . In one of methods, a square patch with mitred corners on low dielectric substrate together with some of smaller square parasitic patches on a substrate with high permittivities is introduced, which tends to reduce the antenna size, generate circular polarization, and increase the frequency bandwidth. In another method, for the increase of antenna bandwidths. We use appropriate feeding systems, impedance matching techniques and increase of substrate thickness. These techniques have been use in such a way to produce antenna miniaturization. Then production structure integrated using SIW technique. In third method, design a miniaturized multiband microstrips antennas with helical slot patterns on patches. Then, a novel microstrip notch filter with slotted patch resonator is introduced which may be used for rejection of spurious signal frequencies and prevention of wave interference (for example rejection of the WLAN frequency bands from the UWB communication systems). Finally, survey influences body on UWB antenna and introduce a method for reduction of influences Body on radiation antenna.

  defence date: 2010/07/06 Time: 17:00