| In recent years, there has been increasing interest in wideband phased-array radar due to its wide applications in military and commercial areas, such as, microwave imaging, target identification, low angle of elevation tracking and anti-jamming, etc. In this thesis, several compact wideband antennas have been designed and analyzed for different X-band wideband phased-arrays.(1) Two wideband Vivaldi antennas have been designed and analyzed, with the antenna gain of more than 10 dB within 8GHz~14GHz. A novel wideband Microstrip-to-CPS balun is designed and applied as the feeding structure of the Vivaldi antenna. In addition, an X-band five-elements Vivaldi antenna array with wide bandwidth and wide beamwidth is designed and fabricated.(2) A low profile wideband Bunny-Ear antenna with wide beamwidth has been designed. The antenna is of 33% size of the compact X-band Vivaldi antenna, with monopole type radiation patterns. With proper notches, the bandwidth and gain of the Bunny-Ear antenna have been improved. The antenna is then applied for the 32-elements triangular grid array with the periodicities of 22mm in the E-plane and 15mm in the H-plane. The antenna array is Taylor weighted with low sidelobe. In addition, an 8-element array is fabricated and measured, demonstrating good impendance matching and radiation pattern over the whole X-band.(3) A coupling based X-band Vivaldi antenna is designed. The antenna width is reduced to be 14mm, which is 70% of the compact X-band Vivaldi antenna. In addition, a 7-elements triangular grid antenna array (with the spacing of 14mm in the E plane and 15mm in the H plane) is designed and fabricated. The Vivaldi antenna is demonstrated to be with good matching and wide beamwidth within 8GHz~16GHz, which can be applied for two-dimensional wide angle scanning.(4) A tear shaped antenna with reflector has been designed and fabricated, demonstrating the antenna bandwidth of 104%. |
PDF Full Text Request