A novel 1-bit reconfigurable transmitarray antenna (RTA) based on a Yagi-Vivaldi unit cell for wideband and beam scanning application at the Ku-band is presented. The unit cell consists of a tightly coupled microstrip (MS) Yagi antenna and a Vivaldi antenna as the receiving and transmitting elements, respectively. To achieve a reconfigurable performance, a novel slot line to MS line phase shifter with a pair of reverse-mounted p-i-n diodes was introduced, and a 180° phase difference was achieved based on the current reversal mechanism. To improve the oblique incidence performance of the unit cell, a metasurface based on subwavelength metal crosses was loaded in front of the antenna, and the scan loss in the H-plane was improved by 2 dB. An RTA prototype with 16×16 unit cells was designed, fabricated, and tested. The measured 1 dB bandwidth of the RTA is 14% with a maximum gain of 22.3 dB at 13.6 GHz, corresponding to an aperture efficiency of 25.6%. Good beam scanning performance has also been achieved with a scan loss better than 4 dB in both the E-plane and the H-plane at 60°.

In this paper, a folded low-profile wideband 1-bit reconfigurable transmitarray (RTA) with 2D beam-scanning capacity is proposed. To reduce the profile of the whole RTA, the ray tracking mechanism and the feed optimization is introduced. A 1-bit wideband RTA element with polarization selection function and polarization rotation function is designed based on a regular hexagonal resonant patch and PIN diodes. Furthermore, a specially designed waveguide structure is fabricated to verify the performance of the RTA element. To achieve the low-profile design, a wideband polarization rotation reflectarray (PRRA) element acting as the reflecting surface is proposed and a 2×2 U-slotted planar patch antenna is designed to replace the horn. With these designs, the profile can be compressed by two-thirds compared with the conventional space-fed architecture. A 16×16-elements low-profile RTA is designed and fabricated. The measured and simulated radiation patterns are in good agreement. The measured peak gain is 19.6 dB, corresponding to an aperture efficiency of 13.8%, and the measured 3-dB gain bandwidth is 17.5% (from 15.1 GHz to 18 GHz). Good scanning performance with ±60° scanning coverage in both principal planes has been obtained, and the scan losses are 3.97 dB and 4.15 dB respectively. Besides, the measured SLLs and cross-polarization levels remain better than -15 dB and -20 dB, respectively, at all beam directions.

In this paper, a 1-bit wideband electronically reconfigurable reflectarray (RRA) in Ku-band is proposed. In order to achieve the wideband and reconfigurable characteristics, the stacked microstrip structure and a 1-bit “microstrip line-slot line-microstrip line” phase shifter (MSMPS) were introduced in this design. A novel “receiving-phase shift-transmitting” unit cell was gotten by connecting two stacked microstrip structures using MSMPS. Due to the receiving and transmitting parts are perpendicular to each other, the polarization rotation characteristic was demonstrated. To avoid the blockage of the feed horn, it was placed above the reflecting surface array with an offset angle of 25° to the normal direction. A $16\times16$ obliquely-fed RRA was designed and fabricated. The measured 1-dB gain bandwidth of the RRA is 15.4%. The measured results show that the fabricated prototype can achieve beam scanning from −20° to 50° in the elevation plane, and ±50° beam scanning in the azimuth plane.

In this paper, a novel singlet based on TE$_{301}$ mode resonant cavity is first introduced and analyzed. By using the mode cancelling between the dominant resonance and the spurious resonance, a transmission zero (TZ) is then produced. Furthermore, the position of TZ can be controlled properly by changing the dimensions of the resonant cavity. Based on the novel singlet, a fifth-order filter centered at 140 GHz with two TZs at 131 and 151 GHz has been presented and fabricated by conventional computer numerical control-metal-milling technology. The measured results are in excellent agreement with the simulated ones with a low insertion loss of 0.52 dB and a 3-dB bandwidth of 13 GHz. A high selectivity with a 40 dB outband rejection at 132 and 149 GHz is achieved.

A simultaneous transmitting and reflecting reconfigurable array (STAR-RA) with independent beams is proposed in this paper. This STAR-RA can realize bidirectional beams simultaneously and the forward and backward beam directions can be controlled independently. To realize this function, a novel element consisting of the forward and backward phase-controlling patches is proposed. With the help of two pairs of PIN diodes, it divides the incident wave into a 1-bit reconfigurable reflecting part and a 1-bit reconfigurable transmitting part. Further, a STAR-RA prototype with 16 × 16 elements is designed, fabricated, and measured. The measured results show a good beam-scanning capability of ±60° with a maximum gain fluctuation of 5.5 dB in E- and H-planes for both the transmitting and reflecting beams. The 1-dB gain bandwidth of the STAR-RA is 8.4% from 5.7 to 6.2 GHz. The distinctive advantage of the proposed design is the independently controlled bidirectional beams that work simultaneously, which is suitable for bidirectional wireless communication applications.