Investgation Of W-band Beam-scanning Array-Fed Reflector Antenna

An increasing demand on operating bandwidth and resolution ratio to object identification for modern wireless communication system is put forward.Contributed to a wider absolute bandwidth,millimeter wave band can meet the abovementioned requirements.As an important atmospheric window within the millimeter wave band,W-band(75 GHz to 110 GHz)has a significant research value.In order to achieve the application requirements of long-distance communication and wide beam coverage,using an array feed,which is used to replace the horn antenna,to feed a large-aperture reflector antenna can be a suitable choice.In this paper,the W-band array-fed reflector antenna(AFRA)is investigated based on subatrate integrated waveguide(SIW).The research contents mainly include the following aspects:First,to realize the characteristics of multi-polization and wide bandwidth for the beam-scanning reflector antenna,the W-band AFRA with a ports-switchable integrated array feed is researched.Using the linear polarized patch antennas with array scales of 4×4 and 8×4,which are fed by SIW slot,as the array feeds.The 34-dBi reflector antenna with beam scannable ranges of –2.1°~2.7° and –5.8°~–0.9° is achieved.On this basis,to achieve the characteristic of multi-polization,the circular-polarized 4×4 patch array feed,which is fed by SIW slot,is designed and the patch has a rotation of 45°.Then,the 33-dBi reflector antenna with a beam scannable range of –2.3°~2.5° and an axis ratio less than 2.5 dB is achieved.Meanwhile,to improve the characteristic of bandwidth,the 4×4 SIW varing-length slot array antenna is adopted as the feed.The 32-dBi reflector antenna with a beam scannable range of no less than –2.2°~2.3° within the entire operating bandwidth(86GHz~94GHz)is achieved.Next,aiming to widen the beam coverage and improve the performance of scanning loss for the reflector antenna,the W-band AFRA with an amplitude-phase-controlled array feed is researched.To achieve the wide beam coverage,the influence of different array arrangements(element spacing,subarray configuration)for the array feed on scanning performance is analyzed firstly.Meanwhile,to reduce the element amplitude dynamic range,the defocused distance is optimized.To further improve the performance of scanning loss,the influence of spatial positions for the subarray on the radiation performance of reflector antenna is researched.Based on that,the three-dimensional topological 12×4 array feed,including 3 indepentantly controlled subarray feeds,is implemented.Fed by the amplitude-phase-controlled array,the simulated gain of the reflector antenna reaches up to 40.3 dBi and the beam coverage is –6.5°~5.5°.The scanning loss is improved from 1.9 dB to 1.6 dB compared with the conventional planar array feed.To verify the beam-scanning capability of the reflector antenna,the subarray feed antennas for different beam directions of –0.5° and –6.5° are designed and fabricated.The measured results agree well with the simulated ones.