Dual-Band Antenna With Large Beam Steering Angle Incorporating Endfire and Frequency Scanning Modes Using Double-Layer SSPPs Structure

A dual wideband antenna with a large beam steering angle through endfire radiation and frequency scanning radiation in each band is proposed for the first time. The antenna utilizes a double-layer (D-L) spoof surface plasmon polaritons (SSPPs) structure which exhibits stronger field confinement and lower cutoff frequency than the single-layer (S-L) SSPPs structure. The modulated D-L SSPPs structure can excite the space harmonic distributing in the fast-wave region and retains transmission in the slow-wave region. By combing the modulated D-L SSPPs waveguide and the Vivaldi radiator, both the slow-wave radiation (endfire mode) and the fast-wave radiation (frequency scanning mode) can be aroused in the two operating bands. An example antenna is designed and fabricated. In the slow-wave range from 3 to 9 GHz, the antenna works in the endfire mode with the beam direction of 90° and the realized gain varying from 3.55 to 8.24 dBi. Within the fast waveband from 13 to 34 GHz, the antenna operates in the frequency-scanning mode, accomplishing beam scanning from −90° to ±42.5° with the realized gain of 9.45–15.67 dBi. Thus, the proposed dual-band antenna can achieve two operating bands and two radiation modes, which offers a 180° beam-changing angle in total.