Study Of A Number Of New Planar Antennas

Antenna is the crucial equipment of the radio application systems. Planar antenna has small size, light weight and low profile. Because of all those characteristics, the planar antenna is easily to be integrated with circuits. In recent yeas, with the great development of manufacture workmanship of the antenna, the planar antenna has become a new star in many applications. In this thesis, three different types of planar antennas are designed and fabricated.A 35GHz H-shaped aperture-coupled microstrip antenna for the element of MEMS millimeter phased antenna arrays is presented in chapter 2. In order to integrate the antenna element with the MEMS phase shifter, multilayered structure is applied in the design. It allows for the electromagnetic separation of the radiation of the microstrip patch and the feed network with the use of the ground plane. The simulated results show that the antenna has rather high gain and wide bandwidth. At 35GHz, the S11 of antenna is -48dB,and the bandwith (S111<-10dB) is 2GHz, the gain is about 4dB. A novel broad band PBG structure for microstrip line has been proposed in chapter 3. The bandwidth of the stop band is about 6GHz. The relative bandwidth is over 55% and the return loss in the band of interest is at least -47dB dB. The experimental and simulated results are in good agreement. It was applied to a microstrip slot antenna. The experiment result shows that the antenna gain is improved about 1dBA uniquely S-shaped compact dual-band planar inverted-F antenna is proposed for WLAN applications in chapter 4. The designed antenna can work in both 2.45GHz and 5GHz frequency bands. Although the height of the antenna is reduced to 4 percents of working wavelength (2.25GHz), the patterns of the antenna in both low- and high-frequency bands are essentially omni-directional by optimum tuning. Moreover, the antenna keeps the vertical polarization in respect to the antenna surface.