Beam Scanning Capability Research Articles

A Wideband Conformal Array Antenna With Dual-Polarized Transmission and Reflection Element for Full-Space Beam-Scanning Capability

A Wideband Conformal Array Antenna With Dual-Polarized Transmission and Reflection Element for Full-Space Beam-Scanning Capability

Two-dimensionally high AR performance beam scanning utilizing randomly-rotated single-PIN-diode elements for circularly-polarized programmable metasurface

In this paper, we introduce a novel technique that utilizes randomly rotated elements (RREs) for the cross-polarization and axial ratio (AR) control of a circularly polarized programmable metasurface (CPPMS). We evaluate the CPPMS performance by comparing RREs layout with uniform elements (UEs) layout, and analyze far-field radiation parameters for 50 groups of CPPMS with different RREs layouts. Simulation results demonstrate consistent and improved performance across various RREs layouts, showcasing reduced cross-polarization and enhanced AR beamwidth. To validate these findings, we design a 1-bit CPPMS in Ku-band comprising 20 × 20 elements with the optimal RREs layout, and conduct measurements in an anechoic chamber. The CPPMS prototype achieves high gain (22.34 dBi), low cross-polarization (-20.5 dB), and a narrow 3 dB AR beamwidth (8.93°). Notably, it offers wide-angle beam scanning capabilities of up to ±60°. The gain bandwidth at -3 dB ranges from 14.54 to 16.65 GHz, with a relative bandwidth of 7.3%, while the 3 dB AR bandwidth extends from 14.24 to 16.07 GHz. Consequently, the proposed 1-bit CPPMS exhibits high-performance two-dimensional AR beam scanning, presenting promising applications in satellite communications.

Power screw-assisted reconfigurable reflective metasurface with spatial modulation

Reconfigurable reflective metasurfaces (RRMs) have garnered significant attention due to their capability to control reflection characteristics. While conventional metasurfaces manipulate the phase and amplitude of the reflected beam through the arrangement of sub-wavelength scatterers in a periodic array, achieving dynamic manipulation typically necessitates external stimuli. Alternatively, spatial modulation within a metasurface introduces gaps in the metastrips, enabling a spatial phase shift across the reflected beam and facilitating real-time beam steering and shaping. This paper proposes a novel power screw-assisted reconfigurable reflective metasurface for achieving beam control and spatial modulation. The design integrates a power screw into the metasurface structure, providing controlled displacement and continuous beam scanning capabilities. Experimental results demonstrate that the proposed metasurface can scan from ±32° to ±15° at 28 GHz. Unlike current designs requiring complex external control systems for beam scanning, this approach offers a simpler yet powerful method for real-time control of the reflected beam. The novelty of this work lies in the integration of the power screw mechanism, presenting a promising advancement in the field of reconfigurable reflective metasurfaces with potential applications in communication systems, energy harvesting, and adaptive optics.

Dual-polarized bidirectional beam-steering array with beam-scanning capability in full-space

This paper presents a dual-polarized bidirectional electronically reconfigurable beam-steering array (DBSA) for the first time, which integrates the beam-scanning capabilities of both dual-polarized reconfigurable transmitarray and dual-polarized reconfigurable reflectarray. First, a novel phase and direction reconfigurable dual-polarized element is proposed. Four PIN diodes are soldered onto the symmetric transmitting patches to tune the 1-bit transmission phase, while two PIN diodes are soldered onto the reflecting patches to tune the 1-bit reflection phase. By controlling the states of the PIN diodes, the DBSA element can achieve 1-bit reconfigurable phase in both transmission and reflection modes. Second, based on the proposed element, a 100-element DBSA prototype is fabricated and measured. At dual-polarization, the angles of the scanned beams can reach 45∘ and 222∘ in forward- and backward-spaces. Therefore, the proposed novel method opens a new avenue to designing a dual-polarized electronically reconfigurable spatially fed array antenna with full-space beam-scanning capabilities, and the proposed design is suitable for dual-polarized bidirectional wireless communication applications.

Wide-Angle Scanning and High Isolation Dual-Polarized Base Station Antennas for Sub-6 GHz Applications

This paper presents a wide-angle scanning and high isolation base station antenna array. The antenna element employs a compact dual-polarized umbrella-shaped printed dipole with a small size of 0.23λ0 × 0.23λ0 × 0.26λ0, which provides the possibility for a small element spacing array. The antenna element possesses wide 3 dB beamwidth of 84.6∘ benefiting from the pulling down of the dipole arms. Then, a dual-layer metal superstrate structure and metal wall is adopted to mitigate different kinds of mutual coupling between the dual-polarized antenna elements in the array. Owing to the wide beamwidth of the element and the low mutual coupling between the elements, the final 4×6 antenna array can achieve a good beam-scanning capability with maximum scanning angle up to ±55∘ and a small gain variation of less than 3 dB over the operation band 3.3-3.8 GHz. The fabricated array shows the measured isolation between all ports of the antennas is increased to more than 20 dB. Scanning characteristics also agree well with the simulated results. With the merits of wideband, low-cost (simple design and easy fabrication), wide-angle beam-scanning capacity, and good radiation performance, the proposed design has potential for application in 5G base stationsystems.

Dual-Band Coradiator Antenna Employing Cascaded Triangular Cavities With a Steerable Beam in the Millimeter-Wave Band

A dual-band coradiator antenna with a beam-scanning capability for the sub-6 GHz andmm-wave bands is proposed in this paper. First, four subarrays based on cascaded triangular cavities are arranged using a mirror operation to form the mm-wave antenna array. Then, four mm-wave subarrays are connected at the position where the electric field is at a minimum on their edges. Lastly, the entire mm-wave array structure resonates in the microwave band, which can be equivalent to a shorted quarter-wavelength patch antenna in the sub-6 GHz band. Hence, the same radiator can work as both a sub-6 GHz antenna and a mm-wave antenna array with broadside patterns in both cases. Attributed to the novel co-radiator structure, the proposed design is simple and compact. An interdigital coupled line with a high-pass filtering characteristic is inserted into each mm-wave feeding line to enhance the isolation. Besides, two parasitic patches are loaded to increase the microwave bandwidth. The experimental results show that the peak gain at 2.56 GHz is 3.2 dBi and at 28 GHz is 14.3 dBi for the sub-6 GHz and mm-wave bands, respectively. The isolation among different feeding ports is greater than 15 dB and the mm-wave array also provides ±38° beam scanning performance.

Dual Frequency Multi-Functional via-Less Leaky Wave Antenna Featuring Enhanced Frequency Sensitivity and Dual Beam Scanning Capability

Dual Frequency Multi-Functional via-Less Leaky Wave Antenna Featuring Enhanced Frequency Sensitivity and Dual Beam Scanning Capability

Design of a 2*2 Microstrip Phased Array Antenna for Radar Applications

Micro-strips patch antennae used in array configurations are more beneficial than single antenna element by augmenting the directivity (dB) radiation pattern, and lowering the substrate's permittivity to overcome its drawbacks, which include poor gain, low efficiency, narrow bandwidth limited directivity. It also facilitates beam-steering capability which is obtained by enabling phase difference(β) between the antennas. Beam scanning capability is used in radar and GNSS technologies. This paper proposes a 2*2 microstrip phased array antenna by using rectangular microstrip patch antenna on an FR-4 dielectric substrate for beam scanning. The resonant frequency of the antenna is at 2.52GHz frequency with a good Voltage Standing Wave Ratio (VSWR) value of 1.1325. The design has been simulated in Ansys HFSS software. The simulation results exhibit antenna better performance of the proposed antenna compared to state-of-art designs present in the literature. The compactly designed Rectangular Micro-strip Patch Antenna array shows a low S-parameter (–24.127858 dB), high gain (13.689104 dB), directivity (14.055125 dB), and efficiency of 91.917%.

Leaky wave antenna with backfire to endfire beam-scanning capability based on even mode spoof surface plasmon polaritons

In this paper, a leaky wave antenna (LWA) based on even mode excited spoof surface plasmon polaritons (SSPPs) is proposed. The LWA can radiate beams from backfire to endfire as the frequency increases. The proposed LWA is asymmetrically modulated by the method of sinusoidal modulation of the reactance surface at two sides of the SSPP structure, which brings a phase difference between two sides of the antenna. The phase difference produces the field component that radiates the beam in the backfire or endfire direction. In this way, the full-angle beam scanning is realized. Moreover, to reduce the open-stop band effect, an improved LWA with multiperiod modulation and asymmetric units is proposed. The simulated results indicate that the radiation beam steers from backfire to endfire. A prototype of the proposed LWAs is fabricated and measured. The measured results agree well with the simulated ones.

Low-Profile P-I-N-Diode-Controlled Bezel Fit Radiation-Pattern Reconfigurable Antenna Arrays for 5G Smartphones

The spatial coverage of a 5G smartphone antenna array is an important factor to consider in the design and implementation of 5G wireless communication systems. In this paper, we present a compact, low-profile, and reconfigurable radiation pattern mm-wave smartphone antenna array that can provide high spatial coverage through its hybrid structure and beam-scanning capabilities. The proposed antenna array introduces PIN diode-controlled strips that enable beam tilting of (±)50° in the vertical direction with respect to a smartphone. In addition, the antenna array can beam scan (±)45° while maintaining a gain of >5 dBi. The compact antenna array measures 28 mm × 5.5 mm × 0.508 mm, including the director and reflector, which are situated next to the antenna. The array exhibited a wide –6 dB impedance bandwidth of 3480 MHz (26.42–29.90 GHz) and >25 dB of isolation in the simulation environment. The on/off state of the diode results in three operating modes of the antenna array: (a) broadside -x, (b) broadside, and (c) broadside +x modes. The radiation performance of the antenna array was analyzed in each operating mode, with and without a smartphone present. Additionally, power density analysis was performed for safety analysis using a frequency–dependent homogeneous hand and head model while the antenna array was installed in a smartphone model. Finally, an antenna array was fabricated, and the measurement results were verified, showing good agreement with the simulated results.

Design of Low-Cost Single-Layer 2-Bit Reflective Programmable Metasurface Based on Folded Ground

A low-cost single-layer 2-bit programmable metasurface (PM) is proposed in this article. This PM is processed on a single-layer printed circuit board (PCB) with the microwave structure, ground, and bias lines, enabled by a folded ground. The folded ground design moves a part of the ground from the bottom to the top layer to leave an area for bias lines. Vias are used to connect the ground in top and bottom layers to form a whole. The bias line in the microwave structure area is grounded by two capacitances to isolate microwave current with the bias line area. An asymmetric patch is designed in microwave area as the 2-bit microwave structure. To verify the microwave performance of this PM, functions of generating double beams, electromagnetic (EM) waves with orbital angular momentum (OAM), and a high gain beam are simulated. The far-field pattern of a 16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 16 PM antenna in beam scanning is measured. The measured results show that the PM antenna has a beam scanning capability of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> and a maximum aperture efficiency of 44.6%. Finally, to illustrate the universality of the folded ground design, the varactor-loaded continuous phase adjustable PM and variable polarization 1-bit PM are discussed.

3D Printed Multi-Beam OAM Antenna Based On Quasi-Optical Beamforming Network

In this paper, a multi-beam orbital angular momentum (OAM) antenna is proposed. By employing 3D printed millimeter-wave quasi-optical beamforming network (BFN), the emitted OAM wave can realize passive beam scanning capability. The antenna is composed of a pillbox BFN, a slotted waveguide antenna (SWA) array, and several full-dielectric phase elements (PEs) on the top of the SWA array. The required phase distribution of the OAM beams is turned by the phase shifts of the PEs. The pillbox BFN can generate the input waves with different phase gradients for the SWA array, and thus steer the beam direction. Moreover, the folded structure of the pillbox BFN can greatly decrease the size of the antenna. The proposed topology can be easily expanded to realize more beam number, higher directivity, and other OAM modes for its periodical structure. To verify the performance of the proposed antenna, a prototype is fabricated and measured. Two types of 3D printing technology are used, i.e., selective laser melting (SLM) for the pillbox BFN and the SWA array, and fused deposition modeling (FDM) for the PEs. The application of the 3D printed method greatly helps to decrease the fabrication difficulty. The measured results show that the antenna can achieve five +1 mode beams with ±20° 3 dB beam coverage range. Moreover, due to the full-metal structure of the BFN and the SWA array, the proposed design can achieve the minimum efficiency of 83.2%, which is much better than the other printed circuit broad (PCB) based OAM antennas. The advantages of low-cost beam scanning capability and the extensibility make the proposed antenna topology a good choice for future OAM communication and sensor systems.

Theory, Design, and Verification of Miniaturized Phase-Controlled Huygens Antenna for 360° Continuous Beam Scanning

The theory, design, and verification of a novel miniaturized reconfigurable Huygens antenna with 360° continuous beam-scanning capability are demonstrated in this article. Different from the conventional Huygens topology, both the monopole-like Huygens form and the metamaterial loading technique are explored for size reduction. By creatively tuning the direction (or polarization) of the electric dipole (E-dipole) or magnetic dipole (M-dipole), a novel miniaturized pattern reconfigurable Huygens source is first proposed. Then, to control the polarization of the M-dipole [linearly polarized (LP)], a double circularly polarized (CP) wave with a tunable phase difference is introduced. Furthermore, a novel phase-controlled Huygens mechanism is developed by combining the polarization reconfigurable M-dipole and fixed E-dipole. By modulating the feeding phase of the Huygens source, the beam can be steered in any direction in the horizontal plane. The proposed theory and working principle are verified by a metamaterial-loaded tri-mode dielectric resonator radiator and a three-way phase-shifting network. The antenna is operated from 3.40 to 3.68 GHz and is capable of continuously scanning a directional beam from 0° to 360°. The realized peak gain and 3 dB beamwidth are greater than 6.3 dBi and 90°, respectively. This work proposes a new realization method for a simple, low-cost, miniaturized, vertically polarized (VP), 360° continuous beam-steering antenna. It is promising for intelligent wireless communications, the Internet-of-Things (IoT) devices, and DOA estimation applications.

One‐bit wideband reconfigurable reflectarray with stable beam‐scanning gain for X‐band application

AbstractA wideband and electrically reconfigurable reflectarray (RRA) is presented for X‐band application. The unit cell is composed of two heterogeneous resonators, that is, a split resonator ring and a metallic patch, and two positive‐intrinsic‐negative (PIN) diodes integrated between these two resonators. A bias circuit on the bottom layer is designed to achieve the switching of the two states via properly placing the PIN diodes on the resonators with minimal electric field. One‐bit phase quantization is obtained by switching two different resonant mode via controlling the ON or OFF state of two PIN diodes. The simulated results show that the proposed unit cell can achieve one‐bit phase quantization with 180° ± 20° and reflection coefficients of ‐1 dB from 9.5 to 10.8 GHz, corresponding relative bandwidth of 12.81%. In addition, a fully functional 12 × 12 RRA fed by a linearly polarized horn is theoretically designed, simulated, and fabricated. The measured results show that the main beam can be steered from −50° to +50° at operating frequency, for example, 10.1 GHz with 1.5 dB gain loss within the scanning range and 20.34% aperture efficiency. In addition, the measured average gain is about 17.5 dBi and 3 dB gain bandwidth is about 15.68% from 9.4 to 11 GHz. In virtue of wide bandwidth, stable radiation gain, and good beam scanning capability, the proposed RRA is promising for future wireless communication and radar.

A 3-D-printed Wideband Millimeter-Wave Fan-Beam Antenna With Flat-Top, Sharp Cutoff Patterns, and Beam-Scanning Capability

This article presents a wideband millimeter-wave (MMW) fan-beam antenna with a flat-top, rapid cutoff radiation pattern, and beam-scanning capability through the use of 3-D printer technology. The proposed antenna, consisting of several periodic structures that composed of dielectric and air slabs, is fed by the WR-28 waveguide. By tuning the ratio of dielectric slab thickness to that of unit cell, the effective permittivity is controlled flexibly. The phase distribution on the aperture is carefully modulated in this way to devote high-quality flat-top patterns. In addition, the beam can be continuously scanned within the angle range of 70° without scarifying the gain performance dramatically. For demonstration, a prototype with boresight fan-beam radiation is first fabricated and measured. The proposed antenna achieves an impedance bandwidth of 50% from 24 to 40 GHz. Measured results indicate that the wide beamwidth patterns show flat-top and sharp cutoff performance. Both E-plane and H-plane patterns draw low cross polarization (smaller than −22 dB). Another prototype, aiming to verify the beam-scanning capability, is investigated. Measured results demonstrate the performances of the proposed antennas. With such favorable electrical performance, simple structure, and low-cost fabrication, the proposed antenna is a promising candidate for 5G MMW and satellite applications.

An SIW Pillbox-Based Compact Dual-Polarized Multibeam Antenna With Passive 2-D Beam Scanning Capability

In this brief, a dual-polarized multi-beam antenna is proposed based on substrate integrated waveguide (SIW) pillbox beamforming networks (BFNs). By using a rotationally symmetrical frequency scanning leaky-wave antenna (LWA) array and four SIW pillbox BFNs, the 2-D beam steering capability is realized for two polarizations. Due to the rotationally symmetrical geometric characteristic of the LWA, the orthogonally placed BFNs can excite orthogonally polarized beams. A stable gain with a wide beam scanning range in the limited bandwidth is realized, where only the backward to broadside scanning region of the LWA is used, and the forward radiation is compensated by the axisymmetric BFN. Moreover, the stacked layout of the multi-layer antenna structure greatly helps realize miniaturization. The proposed antenna can provide ±35° beam scanning range by switching 7 ports in the multi-beam plane and ±31° frequency beam scanning range within the bandwidth of 21 GHz to 27.5 GHz. The advantages of the proposed antenna, including dual-polarization, 2-D beam scanning, low profile, compact size, and low cost, make it a very appropriate choice in millimeter-wave multi-beam radars systems.

A Low-Cost and Low-Profile Electronically Programmable Bit Array Antenna for Two-Dimensional Wide-Angle Beam Steering

An electronically programmable bit array antenna (PBAA) is designed with a low profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.09\lambda _{0}$ </tex-math></inline-formula> at 11 GHz) and 2-D wide-angle beam steering. The planar PBAA is composed of 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times8$ </tex-math></inline-formula> elements, and each of them can be individually addressed through the meticulously designed dc bias. By controlling two PIN diodes and four varactor diodes embedded, the PBAA element provides a maximum phase shift of 337.5° and 16 (4 bit) phase coding states with a 22.5° regular interval. The design is verified through simulations and measurements. The experimental results of the fabricated sample exhibit a broadside gain of 16 dBi, corresponding to the radiation efficiency of 33.1%, and 3 dB gain bandwidth of 11.8%. The sidelobe and cross-polarization levels of the broadside beam are below −19.6 and −30 dB, respectively. Moreover, the main beam is capable of scanning in the range of ±60° <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> ±40°, and the gain fluctuations in E- and H-planes are less than 3.6 and 3 dB, respectively. The design provides flexible 2-D beam-scanning capability while being low cost, low profile, low complexity, and low power consumption, which will benefit various applications with sensing and wireless communication through electromagnetic (EM) waves.

Is CBCT a must for the dental office?

The question is whether a CBCT machine is necessary in the dental office. Setting aside the important aspect of the financial resources of both the dentist and the patient, there is still doubt about the need for a cone-beam CT system within the practice. The possibility to perform an immediate second-level radiological examination is an unquestionable benefit for both the dentist and the patient, but it's also a luxury that (at least in Italy) obligates compliance with provisions, national and regional laws, as well as circulars and regulations. It's here, in the seemingly endless authorization requirements, training, continued education, informed consent and competence limits, that the average Italian dentist loses his way, as the path is not straightforward. The quest for the perfect CBCT protocol requires dental professionals to go back to square one, which is the question: "To have or not to have?". In the case of young patients, protection from unnecessary radiation is even more important. In Italy, this complex matter is regulated by the Ministry of Health through special guidelines aimed at growing subjects [2017]. These guidelines require adaptation of work practices and retention of documents (such as internal processes, patient information notes, informed consent, technical documentation, etc.), in addition to the ability to show documentary evidence of appropriate, complementary, contextual, integrated and undeferrable diligent application of the above. I do believe in the importance of reflecting on the cost-benefit aspect in order to decide whether having CT Cone Beam Scanning capabilities in the dental office is worth the trouble! In conclusion: yes or no to CBCT? To each his own opinion. In this respect, I'd like to ask my colleagues what the status is in their countries regarding this important topic. Is the CBCT use widespread in dental practices, are there any guidelines in place for each country? I'll look forward to your input and insights, which we will gladly publish in our journal! Reference Ministry of Health. National Guidelines for Dental Diagnostic Imaging in the Developmental Age. 2017. https://www.salute.gov.it/imgs/C_17_pubblicazioni_2690_ulterioriallegati_ulterioreallegato_0_alleg.pdf https://www.salute.gov.it/imgs/C_17_pubblicazioni_2690_allegato.pdf.

SIW-Based -Band Leaky-Wave Antenna With Improved Beam Steering Performance

A high-scanning rate leaky-wave antenna (LWA) working at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band with continuous backward-to-forward beam-scanning capability, good open stopband (OSB) suppression and wide scanning angle is exhibited. The proposed LWA is made by etching an array of cascaded high-Q resonators and open discontinuities on the substrate integrated waveguide (SIW). The resonator is designed by combining two symmetrically unbalance split ring resonators (USRRs) on the top surface of the SIW. The LWA's working mechanics were thoroughly investigated through band structure theory. An in-depth interpretation of the LWA's characteristics is provided by studying the surface current distribution and the equivalent circuit model of the resonator structure. The LWA's OSB is effectively alleviated by properly selecting the length of the radiation slot. Yet, the antenna scanning rate is directly improved by the oscillation quality of the resonators (i.e., USRRs), which is realized by tuning the split gap of the USRR. In the experiments, a prototype of the proposed LWA was fabricated and measured. The simulated and measured data show good agreement in terms of the antenna's scanning range and radiation gain. The measured results indicates that a continuous beam scanning from −56° to +48° is rendered over the frequency band from 32 to 36 GHz, which implies a spectral scanning rate of 8.84° per percentage. Finally, it is shown that the average gain can reach up to 9.1 dBi.

Transmitarray Antenna for Conical Beam Scanning

Conventional transmitarray antennas are designed to produce a directional pattern with the beam peak in a single direction when the feed is placed at a distinct location. A real-life application requiring conical beam scanning necessitates the development of antennas with patterns that sweep out a cone in space through successive excitation of feeds placed at multiple locations along the body of the revolution ring focus. In this communication, we propose transmitarrays as an antenna solution that can achieve the conical beam sweep. Compared to the previously reported transmitarrays, the development of an off-axis-fed transmitarray for conical beam scanning requires significant advancements regarding the synthesis and optimization of the off-axis-fed transmitarray. A novel synthesis algorithm is presented based on the optimization of the feed location and a modified transmitarray phase compensation. To validate the approach, an 18 cm transmitarray with a thickness of 0.8 cm operating at 13.4 GHz is designed, simulated, prototyped, and measured. Predictions obtained by full-wave simulations agree well with the measured results. The conical beam scanning capability of the transmitarray is demonstrated through measurements taken with the feed placed at five locations within the ring focus.