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This paper proposes a nonreciprocal array antenna based on spatiotemporal modulation. This approach relies on the drastically different phase response during the frequency conversion processes in the time‐modulated antenna element. A prototype linear array composed of a pair of resonant patches is designed and fabricated for proof‐of‐concept validation. Measured results are in good agreement with simulation. The results show that the proposed array antenna is capable of providing versatile radiation performance for transmission and reception, including reciprocal transmission and reception radiation beams, nonreciprocal symmetric transmission and reception radiation beams, and nonreciprocal asymmetric transmission and reception radiation beams, by manipulating the RF signal phase and modulation signal phase. [ABSTRACT FROM AUTHOR]

This article presents a W‐band three‐layer reflectarray antenna that can be easily fabricated using printed circuit board (PCB) process. The proposed reflectarray element is composed of substrate integrated waveguide (SIW) structure and slot‐coupled patch. By controlling the length of SIW in each element, the compensation phases required for the reflectarray to generate focused beam at in‐band frequencies are realized. However, at the out‐of‐band frequencies, the elements fail to provide the required compensation phases as the incident electromagnetic wave cannot couple to the SIW. Thus, filtering performance is realized. A circular aperture prototype reflectarray comprising of 5024 elements are employed to yield a high‐gain narrow beam. The measured results show that the proposed reflectarray antenna attains a peak gain of 40.5 dB at 94 GHz with aperture efficiency of 41.3%, and out‐of‐band suppression higher than 22 dB. [ABSTRACT FROM AUTHOR]

This paper presents a magnetless nonreciprocal diplexing antenna that uses time modulation. The device combines the functions of diplexers, filters, isolators, and antennas in a highly integrated manner. The magnetless nonreciprocity response is achieved by applying time modulation to the resonators of the filtering structures. These resonators are implemented in quarter‐wavelength microstrip lines terminated with varactors that are time modulated by low‐frequency signals fed from Coplanar Waveguides built on the ground plane of the microstrip structure. A prototype multilayer patch antenna is fabricated, which is fed through two orthogonal feedlines and the radiating square patch is coupled by a square ring slot etched in the ground plane. The experimental results show that a gain of 4 dB, out‐of band rejection of 22 dB, in‐band isolation of 20 dB, and inter‐port isolation of 35 dB is obtained at both 1.5 GHz (lower band) and 1.8 GHz (higher band). [ABSTRACT FROM AUTHOR]