Abstract： A frequency and pattern reconfigurable microstrip patch antenna is designed, which consists of a metal floor with an inverted "Ω" slot and a radiation patch, printed on both sides of the substrate. By changing the operating state of the switching diode located at the center of the floor slot, the local structure and the surface current distribution of the antenna will change, and the antenna's working frequency and direction pattern will be reconstructed. The simulation and measurement results show that the antenna can work in both single-frequency and dual-frequency modes. When the diode is in the on-off state, it first works in single-frequency mode, the resonant frequency of the antenna is at 3 GHz, and its working bandwidth covers the main frequency band of world interoperability for microwave access (WiMAX). While the diode is in the cut-off state, the resonant point of the antenna is at 3 GHz and 5.8 GHz respectively, realizing the dual-frequency working mode. And the operating band covers WIMAX and part of the wireless local area networks (WLAN) band, and the antenna far-field pattern changes with different working modes.

Abstract：A 5.5 GHz band wideband directional pattern diversity antenna based on metasurface is designed, which can be used in single band on-/off-body dual communication mode. By analyzing the characteristic mode of the metasurface antenna, the appropriate directional and omnidirectional characteristic mode is selected, the metasurface structure is modified,the higher-order mode is suppressed, and a suitable feed structure is designed to excite it. Finally, the simulation and test results show that port 1 has omnidirectional radiation characteristics and can be used in on-body communication mode, and port 2 has directional radiation characteristics and can be used in off-body communication mode. The working bandwidth of the two modes of the antenna is 23.6% (4.98 GHz~6.25 GHz), and the in-band isolation is higher than 30 dB.

Abstract：In this paper, a V-band waveguide slots array antenna suitable for FOD detection system is presented. The operation frequency range of the proposed array antenna is 74~79 GHz and the array contains 2 048 elements. The proposed antenna has excellent characteristics such as high gain and low profile by using the form of a multi-mode waveguide slot array antenna and a waveguide power division network. The thickness of the antenna is within 10 mm and the radiation efficiency is above 50%. The experimental results show that the measured and simulated results are agreed well with each other, so it is of good practical engineering application.

Abstract： In order to solve the problem that the receiver of millimeter-wave high-power radar seeker is easy to burn, this paper designs a millimeter-wave microstrip one-divided-eight-sector fan-shaped power divider working in Ka band, which is used in millimeter wave receiving front-end to achieve the function of anti-burning and low noise. The power divider has a compact structure, and has the advantages of miniaturization, low insertion loss and good phase consistency. The power divider, ultra-low noise and low noise amplifier, limiter and its corresponding eight-channel synthesizer are applied to the receiving front-end as a whole, which breaks the bottleneck of the development of millimeter wave high-power seeker and has broad application prospects.

Abstract： In this paper, a composite antenna working in L and C bands is designed. The antenna adopts the composite design of discone antenna and microstrip array gold layer. By loading metal short circuit pull, the discone antenna is miniaturized and broadband, it can transmit horizontally polarized omnidirectional electromagnetic waves at 0.95 to 1.6 GHz. The 2×2 microstirp array transmits high-gain directional electromagnetic waves at 4.25 to 4.35 GHz. The composite antenna is embedded in a metal cavity with a diameter of 200 mm and a height of 26.5 mm, which is easy to conform with the aircraft skin. It can meet the requirements of L-band database function and C-band radio altimetry function. The antenna can be widely used in aviation and aerospace fields.