Millimeter-Wave High-Gain Frequency-Scanned Antenna Based on Waveguide Continuous Transverse Stubs

A millimeter-wave frequency-scanned antenna based on continuous transverse stubs applications is presented in this communication. The waveguide CTS radiation slots are fed by a wideband quasi-TEM linear source generator (LSG). To increase the scanning angle, a nonuniform slow-wave structure is employed underneath the radiation slots to control the amplitude and phase distributions. The LSG is constructed of a parallel-plate waveguide excited by a modified three-stage 1-to-8 power divider, generating high-quality quasi-TEM wave over a wide frequency band. The beam direction is tunable with varying frequency. To validate the design, a prototype array at the Ka-band is designed, fabricated, and measured. Excellent agreement is achieved between simulations and measurements. The measured results show that the proposed array has an impedance bandwidth from 26 to 42 GHz (47%). The peak gain is 22.9-29.2 dBi, and the radiation angle can be scanned from -56.2 degrees to -2.2 degrees. Over the entire frequency band, the first sidelobe is suppressed to below -12.6 dB.