Key Technologies Of Infinite Long Slot Array Antennas With Dual Polarization

With the development of modern radar and EW technologies, people pay more and more attention to phased array antennas. With a good broadband wide-angle scanning capability, infinite long slot array antennas are considered as an excellent candidate for phased array antennas. Owing to the advantages of low profile and ultra-wideband performance, the long slot array antenna is studied in this thesis, which is one typical design of tightly coupled array antennas.Several long slot array antenna elements have been investigated in infinite array environment. The active input impedance of the antenna element is decreased by using a bowtie antenna as the feeding structure. Metal patches printed on two dielectric plates are placed over the antenna element. The simulation results demonstrate that the input impedance of the antenna element is reduced from 300? to 140?. A long slot array antenna consists of 4×8 antenna elements is designed, improved and fabricated. Sixteen elements located along the edge in the E-plane are loaded with 150?. The experimental results illustrate that VSWR is less than 2 over the 5:1 frequency band(0.7-3.5 GHz). The overall dimensions are 0.7?_l ×0.35?_l ×0.18?_l, where ?_l is the wavelength at the lowest operating frequency. The measured gain increases from 6 to 19 dBi within the operating frequency band. The cross-polarization level is less than-30 dB, while the radiation patterns show great directional radiation performance.As we all know, antenna performance is limited by using PEC as a reflector, including profile reduction and the operational bandwidth. A hybrid EBG/Ferrite ground plane is selected as a solution. The simulation results show that the magnitude of the reflected coefficient of the hybrid EBG/Ferrite ground plane is less than-14 dB at low frequency. The phase of the reflected coefficient is between ±90° regardless of the magnitude of the reflected coefficient at high frequency. Feeding by orthogonal stepped dipoles, a dual-polarized long array antenna element in infinite array environment is studied. The simulation results indicate that the proposed element has a wide scanning range of ±45° with the active VSWR less than 3 over the 30:1 frequency band. The isolation between two lumped ports is less than-50 dB. This antenna has a profile of 41.5mm, nearly 1/60 of the wavelength at the lowest operating frequency.