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Coding metasurfaces (MSs) provide an effective strategy for designing highly integrated devices due to their powerful ability to flexibly manipulate the wavefront of electromagnetic (EM) waves. To date, it remains a great challenge to theoretically construct and experimentally verify highly integrated MSs for manipulating both linear polarization (LP) and circular polarization (CP) waves in full-space at millimeter-wave (mmWave) and sub-terahertz (sub-THz) bands. In this work, a highly-integrated, low-crosstalk, six-channel coding meta-atom is developed using hybrid phase manipulations, which can achieve independent full-space phase controls for three LP channels and three CP channels across three mmWave and sub-THz bands. To validate the concept, we designed and fabricated a compact coding MS, including refracted four-beam splitting for LP wave at 65 GHz; radar cross section (RCS) reduction, anomalous reflection and dual-vortex beam generation for LP and CP waves at 0.12 THz; two-beam splitting for two decoupled CP waves at 0.154 THz. All the theoretical, simulated, and experimental results agree well with each other. The developed highly integrated MS with multiple independent channels presents a promising candidate for future advanced 5G and 6G systems.

A wideband switchable L-probe patch antenna with reconfigurable 12 linear polarizations (LPs) and dual circular polarizations (CPs) is presented in this letter. We developed a novel feeding method that comprises three different strategies, i.e., adjacent triple feeding strategy enables six LPs, adjacent quadruple feeding strategy enables another six LPs, and orthogonal dual feeding strategy enables dual CPs. Moreover, every set of six LP states excited by same strategy show almost rotationally invariant performance including bandwidths and gains. Through measurement, the antenna exhibits a 35.7% impedance bandwidth in LP states [(2.05 to 2.94) GHz] and a 28.9% impedance bandwidth in CP states [(2.01 to 2.69) GHz], with a 23.8% axial ratio bandwidth [(2.15 to 2.73) GHz]. The measurement results agree well with the full-wave simulation ones.

Digital antenna array-based transceiving platforms are critical for research and development in modern wireless systems, covering 5G communications and beyond fields, satellites, and many other fields. However, existing low-cost platforms, such as software-defined radios, have limited antenna numbers, lack continuous data collection capability and do not support online array calibration. To contribute to filling these gaps, this letter presents a versatile design of a digital antenna array transceiving system. An antenna calibration network is designed to support online self-calibration of all transceiving channels. Utilizing a small onboard storage and the memory of a host computer, a continuous data capturing scheme is developed. The system is implemented and applied in over-the-air experiments for unmanned aerial vehicle (UAV) detection, demonstrating the effectiveness of the developed design and its potential to enable fast development and validation of wireless system applications.

6G technologies are poised to revolutionize telecommunications in the coming decade, building on the commercial deployment of 5G systems. The evolution of 6G is expected to unlock transformative applications, such as connected intelligence, smart cities, artificial intelligence (AI), and digital twins, among others. To support these advancements, antennas and metasurfaces, being fundamental components of wireless systems, will play a pivotal role in shaping and expanding 6G's capabilities.

In this communication, we develop a wideband and high-gain multilinear polarization-reconfigurable antenna integrated with nonuniform partially reflective surface (PRS). It leverages a compact L-probe feed source with 25.71° interval reconfigurable linear polarizations (LPs). A polarization-independent nonuniform PRS with both reflection magnitude and phase control is introduced to significantly enhance the gain of the feed source. Furthermore, a systematic analysis on antenna gain relative to the PRS size is conducted, and the obtained gain can vary from around 15 to 20 dBi by carefully designing the PRS. Besides, a partial metallic cavity is presented to further improve the peak gain without enlarging the antenna. An example of seven-LP reconfigurable antenna was designed, simulated, and fabricated. The prototype achieves an overlapped −10-dB impedance bandwidth from 9.28 to 11.32 GHz (19.8%) and a maximum gain of 15.08 dBi. The 3-dB gain bandwidth is 15.7% (from 9.4 to 11 GHz). These measured characteristics validate the antenna’s good performance in delivering wide bandwidth and high gains across multiple LPs.

A low-profile multiple linear-polarization (multi-LP) reconfigurable cavity-backed magneto-electric (ME)-dipole antenna is developed in this letter. The magnetic-dipole is realized by a TM$_{020}$-mode slotted substrate-integrated cavity, and the electric-dipole is the printed microstrip dipole coupled above the slotted cavity. By introducing a rotationally symmetrical configuration of ME-dipoles with switchable feeding networks, we have realized the reconfigurable multi-LP states for the cavity-based ME-dipole antenna. As a benefit of the dipole-loaded slotted cavity configuration, the antenna profile is only $0.09\lambda _{0}$, which is much lower than conventional reconfigurable ME-dipole antennas. The developed antenna is capable of switching eight LP states at a $22.5^{\circ }$ interval in real time by electronically controlling PIN diodes loaded on the slotted cavity. Measured results agree well with the simulated ones. At the center frequency of 5.04 GHz, a measured maximum gain of 4.46 dB is obtained for all polarization states. It is the first time to achieve simultaneous multi-LPs and low profile for ME-dipole antenna.

Polarization reconfigurable antennas are useful in certain wireless systems to adapt to different incident polarizations or measurement systems. In this work, we develop an innovative and simple frequency-controlled polarization-rotating antenna. The antenna provides continuous adjustment of the orientation of linear polarization (LP) over a range of 180°, making it suitable for applications such as identifying objects with diverse orientations in sensing and detection systems. We introduce a general model of an LP antenna, in which the orientation of polarization can be controlled with an adjustable phase shift. By substituting the phase shift in the model with one that is frequency dependent, a 180° LP rotation can be attained by sweeping the source frequency across a custom-designed bandwidth. This allows the implementation of an antenna system that can continuously adjust the orientation of LP in response to frequency scanning over a wide operating bandwidth. As demonstrated in a prototype, a 180° polarization scan with a realized gain varying between 7.0 and 9.8 dBi is achieved by sweeping the frequency from 9.6 to 11.65 GHz. The continuously frequency-scanning polarization rotation behavior offers a novel and efficient solution for polarization reconfiguration.

This letter proposes a novel technique to produce desired circularly polarized (CP) pencil beams at entire working frequency band for ultrawideband (UWB) planar array while suppressing grating lobes in pencil beams at high-frequency band. The approach is based on a ${\text {2}}\times {\text {2}}$ irregular sequential rotated subarray (ISRS) configuration, using UWB linearly polarized elements. The synthesis procedure involves optimizing initial element rotation angle of each ISRS, while ensuring that the rotation interval of $\pi /2$ is still maintained between neighboring elements of each subarray. The phase term applied to the array elements is determined by the contribution of the phase associated with rotation. The proposed technique suppresses grating lobes in the obtained patterns at high-frequency band more effectively than the sequential rotation technique (SRT) while maintaining a simple sequential phase feeding network compared with the random SRT. Finally, one typical case of synthesizing pencil beam with a planar rotated Vivaldi array is presented to confirm the benefits of the proposed technique.