Query: 1 bit beam

title: Simplified Transmitarray Unit Cell for 1 Bit Beam Steering Operation
abstract: In this paper, a simplified design of transmitarray unit cell for 1 bit beam steering operation is proposed. It can provide 1 bit phase quantization by switching on/off the loading capacitors, which could be realized by using varactors and switching the dc bias voltages between a predetermined value and zero. The proposed unit cell is made of two identical, back to back rectangular patch antennas, coupled through a ground slot. Each patch is cut into halves by a transverse slit, at the middle of which the varactor is loaded. For preliminary verification, two test pieces of fixed beam X band transmitarray (0deg and 20deg from broadside, respectively) based on the proposed unit cell (loaded with and without capacitors) are fabricated and tested. The agreement between the simulated and measured results is satisfactory.

title: Characterization of Tiled Architecture for C Band 1 Bit Beam Steering Transmitarray
abstract: A new implementation of a beam steering transmitarray is proposed based on the tiled array architecture. Each pixel of the transmitarray is manufactured as a standalone unit which can be hard wired for specific transmission characteristics. A set of complementary units, providing reciprocal phase shifts, can be assembled in a prescribed spatial phase modulation pattern to perform beam steering and beam forming in a broad spatial range. A compact circuit model of the tiled unit cell is proposed and characterized with full wave electromagnetic simulations. Waveguide measurements of a prototype unit cell have been carried out. A design example of a tiled 10 x 10 element 1 bit beam steering transmitarray is presented and its performance benchmarked against the conventional single panel, i.e. unibody, counterpart. Prototypes of the tiled and single panel C band transmitarrays have been fabricated and tested, demonstrating their close performance, good agreement with simulations and a weak effect of fabrication tolerances. The proposed transmitarray antenna configuration has great potential for fifth generation (5G) communication systems.

title: Broadband transmission type 1 bit coding metasurface for electromagnetic beam forming and scanning
abstract: Coding metasurfaces make it possible to manipulate electromagnetic (EM) waves digitally by means of several discrete particles. Hence, there have been rapid advances in this field recently. Here we propose a novel design of a broadband transmission type coding metasurface, which is valid to both x and y polarized EM incidences from 8.1 12.5 GHz while satisfies the requirements of 1 bit coding without changing the polarization. Two types of multi layer coding particles with different geometrical parameters are adopted to represent the digital states "0" and "1" which are easily promoted to terahertz and optics through modifying the size scale. To verify the ability to manipulate the EM waves, we first adopt the coding metasurface to achieve broadband beam forming by converting spherical waves to plane waves and realize high directivity pencil beam in far field with low side lobes. We further arrange the particles according to the coding sequence 010101. to steer two symmetrical beams in different directions controlled by frequencies with the maximum range of the scanning angle of 30deg 50.5deg. The good agreements between the simulated and measured results validate the proposed broadband coding metasurface, indicating its huge potential in communication and radar imaging systems.

title: A Novel 1 Bit Wide Angle Beam Scanning Reconfigurable Transmitarray Antenna Using an Equivalent Magnetic Dipole Element
abstract: A novel 1 bit reconfigurable transmitarray antenna (RTA) using an equivalent magnetic dipole element for wide angle beam scanning at Ku band is presented. The RTA element consists of a rectangular patch and a side shorted patch with an equivalent magnetic dipole radiation. A 1 bit phase difference is achieved by controlling two p i n diodes on the side shorted patch based on the current reversal mechanism. The half power beamwidth of the presented antenna element is 142deg in E plane, which is significantly larger than other conventional elements. A RTA prototype with $16\times16$ elements is designed, fabricated, and tested. The measured results show good beam scanning capabilities of the 1 bit RTA. The measured gain in the broadside direction is 21.4 dBi, and the scan gain loss is 3.6 dB for the 60deg scanned beam in E plane.

title: Single Beam 1 Bit Reflective Metasurface Using Prephased Unit Cells for Normally Incident Plane Waves
abstract: A single beam prephased 1 bit reflective metasurface is proposed to achieve single beam patterns under normally incident plane waves. Theoretical analysis and numerical simulations are presented to show that, under normally incident waves, single beam patterns can be achieved by introducing a fixed prephase distribution with two values in the 1 bit metasurface. Compared with conventional 1 bit reflective metasurfaces, the proposed scheme alleviates the inherent limitation of single beam patterns on 1 bit reflective metasurfaces under normally incident plane waves. To verify the proposed scheme, a 1 bit unit cell is designed with a $180^\circ \pm 25^\circ phase difference between the two states for frequencies ranging from 34.3 to 49.9 GHz, and a layer stacking method is proposed to achieve two prephases with a 90deg phase difference. As an example, three 1 bit reflective metasurfaces comprising 20 x 20 unit cells with single beams pointing separately at 0deg, 15deg, and 30deg are designed and measured over frequencies of 37.0 to 41.0 GHz; the measured sidelobe levels are less than 7.8 dB. Simulated and measured results show that the proposed prephased 1 bit metasurface can achieve single beam patterns under normally incident plane waves.

title: Design and Experiment of a Dual Band 1 Bit Reconfigurable Reflectarray Antenna With Independent Large Angle Beam Scanning Capability
abstract: A 1 bit reconfigurable reflectarray antenna with independent dual band phase controlling and large angle beam scanning capabilities is designed and experimentally verified. By exploiting polarization orthogonality, the proposed element achieves 1 bit phase shift at 12.5 GHz for x polarization and at 14.25 GHz for y polarization with only two p i n diodes in each element. The element structure and biasing circuits are optimized. Low element magnitude loss, cross polarization, and out of band interference are verified. A prototype with 256 elements is fabricated and tested. The measured gains are 22.3 dBi at 12.6 GHz and 22.5 dBi at 14.25 GHz, respectively. 2 D scanned beams up to 60deg at both frequencies are measured to demonstrate the independent dual band beam scanning capability. The proposed design can transmit and receive orthogonally polarized signals simultaneously and is believed to be a promising candidate for the point to point full duplex mobile communication applications.

title: Single Beam 1 Bit Reflective Metasurface Using Pre Phased Unit Cells for Normally Incident Plane Waves
abstract: A single beam pre phased 1 bit reflective metasurface is proposed to achieve single beam patterns under normally incident plane waves. Theoretical analysis and numerical simulations are presented to show that, under normally incident waves, single beam patterns can be achieved by introducing a fixed pre phase distribution with two values in the 1 bit metasurface. Compared with conventional 1 bit reflective metasurfaces, the proposed scheme alleviates the inherent limitation of single beam patterns on 1 bit reflective metasurfaces under normally incident plane waves. To verify the proposed scheme, a 1 bit unit cell is designed with a 180* 25* phase difference between the two states for frequencies ranging from 34.3 to 49.9 GHz, and a layerstacking method is proposed to achieve two pre phases with a 90 degree phase difference. As an example, three 1 bit reflective metasurfaces comprising 20 x 20 unit cells with single beams pointing separately at 0, 15 and 30 degrees are designed and measured over frequencies of 37.0 to 41.0 GHz; the measured sidelobe levels are less than 7.8 dB. Simulated and measured results show that the proposed pre phased 1 bit metasurface can achieve single beam patterns under normally incident plane waves.

title: 1 Bit Electronically Reconfigurable Folded Reflectarray Antenna Based on p i n Diodes for Wide Angle Beam Scanning Applications
abstract: In this communication, an electronically reconfigurable folded reflectarray antenna (ERFRA) which includes <inline formula> <tex math notation="LaTeX"$14 \times 14$ /tex math>/inline formula> reflecting elements and features a fully planar compact configuration and wide angle beam scanning performance, was developed, fabricated, and tested. A novel reflecting element that is able to carry out cross polarization rotation and electronically reconfigurable 1 bit compensation phases was first developed. After experimentally demonstrating its feasibility, the new reflecting element was then applied to the design of a <inline formula> <tex math notation="LaTeX"$14 \times 14$ /tex math>/inline formula> ERFRA, with a planar feed in the center of the reflectarray and a beam control system based on the field programmable gate array (FPGA) The measurements of the fabricated ERFRA prototype show a wide beam scanning range, up to 60deg, a peak gain of 17.07 dBi, and an aperture efficiency of about 13.2%

title: Real Time Mode Switching and Beam Scanning of High Gain OAM Waves Using a 1 Bit Reconfigurable Reflectarray Antenna
abstract: A reconfigurable electromagnetic surface has been studied to realize the adjustable orbital angular momentum (OAM) beams for real time wireless communication and dynamic target detection in the future. OAM mode switching realized by many previous designs suffers from low gains without OAM beam scanning. In this article, a 1 bit reconfigurable reflectarray antenna is designed, fabricated, and tested for the real time control of OAM mode switching and large angle vortex beam scanning in three dimensional space. The proposed reflectarray surface is composed of 1 bit electronically reconfigurable cells, and the size is 24 l x 24 l with 2304 units. The reconfigurable element is designed by using a radiation patch loading a PIN diode with effective control of two states, "ON" and "OFF" for the demand of 180deg phase difference. The reflectarray surface can be assigned to a code sequence of 0 or 1 by the Field Programmable Gate Array (FPGA) in real time. Henceforth, the coding surface can dynamically control the generation of high gain OAM beams, where only the optimized phase distributions on the surface need to be changed according to demand. To verify the concept, a large scale reflectarray surface is fabricated and measured with an oblique feed at 15deg. Different OAM carrying phase distributions for different OAM beam states are calculated and tested. The test results show that the OAM mode switching between l 1 and l 2 is realized, and other variable modes such as l 3 or l 5 can also be achieved by modifying the phase encoding sequence. Furthermore, the direction of the vortex beams can be accurately controlled with gains over 20 dBi, and the large angle vortex beam scanning is verified. Therefore, all results demonstrate that the proposed 1 bit reconfigurable reflectarray is efficient for the regulation and control of OAM carrying beams for the demand of real time dynamic wireless communications in the future.

title: Versatile Airy Beam Generation Using a 1 Bit Coding Programmable Reflective Metasurface
abstract: The Airy beam, known to present particular unique features, such as diffraction free, self healing, and self bending, has attracted considerable interest in recent years. Here, an electronically controlled reflective coding metasurface is exploited to generate and dynamically manipulate the Airy beam over a wide frequency band in the microwave regime. By judiciously controlling the external dc bias voltage applied to the programmable metasurface, two distinct control states, `0' and `1' are engineered as digital codes for \ensuremath{ \ensuremath{\pi}/2 and \ensuremath{\pi}/2 phase responses, respectively. The programmable binary phase coding metasurface enables the generation and active reshaping of the Airy beam to be numerically simulated and experimentally validated. Moreover, the metasurface allows the bandwidth limitation of passive counterparts to be overcome and is able to modulate electromagnetic waves over a broad frequency range, spanning from 9 to 12 GHz, to realize diffraction free Airy beams.