Thinned Subarray Antenna Design Enabling Dual-Polarization Monopulse Patterns and Beam Steering for Integrated Sensing and Communication Systems

A high-isolation slot antenna array design is presented offering dual-polarization, sum and difference beam patterns with high isolation for integrated sensing and communications (ISAC) applications. The 16-port single-layer design is competitive when compared to the state-of-the-art, and is defined by a sub-array arrangement in a cross-shaped orientation and this setup is made possible by light element thinning of the planar array. Also, the antenna has been designed considering dual-differential, dual-common, or common/differential feeding to generate reconfigurable or agile sum and difference beam patterns as required in the far-field for communications, sensing, or monopulse tracking. Measured isolation ranges for these cases are well above 55 dB for the antenna system ports. Additionally, the maximum realized gain for both polarizations is approximately 22 dBi. We have also demonstrated the beam-steering capabilities of our antenna array using a Butler matrix beamformer, which enables steering up to ±60°. This approach not only provides flexible control over the radiation pattern but also maintains high isolation between the dual-polarization beams. A case study is further reported demonstrating the proposed antenna in a realistic ISAC system setup. Such a low profile, microwave/millimeter-wave antenna array with high isolation can also be useful for full-duplex communication systems, dual-polarized radar sensing, other tracking applications, or whenever a dual-polarization antenna array for beam-steering is required.