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In this letter, we present a holographic metasurface (HMS) based on an orthogonally discrete unit-cell. The proposed unit-cell possesses discrete surface impedance tuning abilities in two orthogonal directions, providing flexible beam formation as a scalar unit-cell and polarization control as a tensor unit-cell. Operation principle and design formulas for generating independently linearly polarized beams and circularly polarized beams using the orthogonal components are concluded. Two example antennas utilizing this HMS are measured to demonstrate the beam formation and polarization control abilities at 11.0 GHz. The first example antenna generates dual beams with independently linear polarizations whereas the second example antenna generates dual beams with independently circular polarizations. Our letter indicates that there exists a middle type of HMS between scalar and tensor HMSs.

This article presents a holographic metasurface antenna with stochastically distributed surface impedance, which produces randomly frequency-diverse radiation patterns. Low mutual coherence electric field patterns generated by the holographic metasurface antenna can cover the K-band from 18 to 26 GHz with 0.1 GHz intervals. By utilizing the frequency-diverse holographic metasurface (FDHM) antenna, we build a near-field microwave computational imaging system based on reflected signals in the frequency domain. A standard horn antenna is adopted to acquire frequency domain signals radiated from the proposed FDHM antenna. A detail imaging restoration process is presented, and the desired targets are correctly reconstructed using the 81 frequency-diverse patterns through full-wave simulation studies. Compressed sensing technique and iterative shrinkage/thresholding algorithms are applied for the imaging reconstruction. The achieved compressive ratio of this computational imaging system on the physical layer is 30:1.

This paper presents the design of 1-bit programmable holographic metasurface (PHMS) concept for monopulse radar applications. A 1-bit programmable unit-cell with only one PIN diode, which can tune the surface impedance for high impedance or low impedance mode as the PIN diode flipped, is proposed. Holographic patterning technique is employed to realize the sum ( $\Sigma$ ) and difference ( $\Delta$ ) patterns based on the proposed PHMS. A 20×20 ( $5\lambda_{0}\times 5\lambda_{0}$ , where $\lambda_{0}$ is the wavelength at 10.0 GHz) PHMS is built and analyzed using a commercial full-wave simulator. The simulated results suggest that two-dimensional $\Sigma$ pattern scanning and one-dimensional $\Delta$ pattern scanning within ±40° are achieved, which can be applied for tracking radar enabled by monopulse technique.