A Wideband Low-Profile All-Metal Cavity Slot Antenna With Filtering Performance for Space-Borne SAR Applications

This letter presents a wideband all-metal cavity slot antenna with a filtering performance for space-borne synthetic aperture radar applications. The proposed antenna element consists of a metal cavity and several radiation slots. It is fabricated by aluminium through milling and welding process, the techniques of which are reliable for the space environment. Benefiting from multiresonances of the cavity and slots, the antenna is able to obtain a wide operating bandwidth. Additionally, the cavity has a very low profile of 2.8 mm, equivalent to 0.093 wavelength at the central operating frequency. An 8 × 12 antenna array is designed, fabricated, and measured for performance verification. The measured impedance bandwidth with S
₁₁
<;-10 dB is achieved from 7.2 to 12.2 GHz, giving a relative bandwidth of 51%. Furthermore, it shows good filtering characteristic with more than 20 dB out-of-band rejections, which is capable to suppress unwanted interferences and contribute to a good electromagnetic compatibility design.