Research On W-Band Microstrip Antenna Arrays

In the W-band,electromagnetic waves have advantages such as short wavelength,wide bandwidth,ability to penetrate the atmosphere,and all-weather operation.They are commonly used in the military field and have broad application prospects in guidance systems,strategic communication,and other areas.The W-band millimeter-wave radar consists of the RF front-end circuitry for generating/processing W-band signals and a Wband antenna array.It can be applied to missile-borne millimeter-wave radar seekers for precise missile guidance.The detection range,accuracy,and anti-interference capability of the W-band millimeter-wave radar determine the missile’s guidance and survival capabilities.These parameters are closely related to the performance of the radar’s antenna,such as gain,beamwidth,and bandwidth.A single antenna is difficult to meet the high requirements of these application scenarios.Microstrip antennas are low-profile,easily conformable,and can be arranged in arrays,making them suitable for practical applications.This study used two low-loss substrate materials suitable for carrying W-band RF circuits as the integrated platforms for millimeterwave antennas.Based on this,research was conducted on W-band microstrip antenna arrays suitable for W-band millimeter-wave radar.The main work contents are as follows:Combining the advantages of low loss and low dielectric constant in the millimeterwave frequency range of quartz substrates,a 4×10 element structure of high-gain and widebandwidth quartz-based microstrip patch antenna array was designed.The operating frequency of this antenna array is 94 GHz.By using a thick substrate and the method of inserted feeding,the bandwidth of the microstrip antenna elements was extended.Compared to ordinary microstrip antennas,the bandwidth was extended by approximately 5%.Based on this element,a non-uniformly fed series-fed microstrip patch antenna array was designed,optimizing the sidelobe level.The antenna array was composed of a feed network that followed the Chebyshev distribution.To facilitate on-wafer testing,a microstrip line-toground coplanar waveguide(GSG)probe test structure was designed.Simulation and test results show that the maximum gain of the quartz-based antenna array reaches 19 d Bi,the sidelobe level in the E-plane is-13.33 d B,the sidelobe level in the H-plane is-18.53 d B,and the relative bandwidth of the antenna exceeds 9%.It basically meets the design requirements of W-band millimeter-wave radar.Using C-cut sapphire as the dielectric substrate,a compact high-gain narrow-beam microstrip comb-shaped antenna array with a 17×16 element structure was designed.The antenna array also operates at 94 GHz.The high dielectric constant of sapphire was utilized to reduce the size of the antenna elements.Microstrip shorting stubs with smaller dimensions were used as the array elements,forming a non-uniformly excited microstrip comb-shaped antenna array.The comb-shaped antenna array,combined with a feed network that followed the Chebyshev distribution,can accommodate more elements within the same area and achieve a narrower beam.The high thermal conductivity of sapphire effectively solves the heat dissipation problem caused by the high transmission loss of W-band electromagnetic waves.Simulation results show that the designed sapphire-based antenna array achieves a gain of 19.05 d Bi,with sidelobe levels reduced to-15.92 d B in the E-plane and-28.29 d B in the H-plane.The relative bandwidth also exceeds 9% and covers the radar’s operating frequency range.The overall beamwidth is narrower,with an E-plane half-power beamwidth of approximately 16.95° and an H-plane beamwidth of approximately 12.1°.