Multibeam Applications Research Articles

SLM Printed Wideband Filtering Antenna With Low Sidelobe and Controllable Bandwidth for K-Band Multibeam Applications

SLM Printed Wideband Filtering Antenna With Low Sidelobe and Controllable Bandwidth for <i>K</i>-Band Multibeam Applications

Multibeam Cylindrical Conformal Array in the Presence of Enhanced Mutual Coupling

The limitations of conventional sensors have made array antennas increasingly crucial for gathering information and communication applications in intelligent transportation and communication systems. Compact cylindrical arrays are particularly favored for their ability to achieve azimuth angle scanning. However, the substantial mutual coupling effect between the elements on curved surfaces and its implication for these arrays remain unclear, which is a key factor to consider when such arrays are used for multibeam applications. This study investigates the effect of mutual coupling in a dual-slant-polarized cylindrical array. The results showed that mutual coupling is predominantly observed among the closely located elements, and it is essential for achieving an ultra-wide bandwidth. The study also analyzes the impact of mutual coupling on the scan impedance and radiation characteristics for multibeam applications and reveals that these arrays exhibit robust multibeam capability, hence having great potential for use in sensing and communication applications.

A Broadband Quad-Beam Patched Leaky-Wave Antenna Based on Substrate Integrated Coaxial Line for Multi-Beam Applications

A Broadband Quad-Beam Patched Leaky-Wave Antenna Based on Substrate Integrated Coaxial Line for Multi-Beam Applications

Cavity-Filter-Based 3-D-Printed Gain-Filtering Transmitarray for Multibeam Applications

Cavity-Filter-Based 3-D-Printed Gain-Filtering Transmitarray for Multibeam Applications

Evaluating Noise in Passive Beamforming Networks for Multibeam Applications

In this work, we identify that the analysis in terms of noise of multibeam passive beam forming networks requires a proper formulation, in order not to overestimate the noise generated by the network. We show that the inherent spatial diversity offered by this type of networks results in an improvement of the SNR, similar to the one obtained by digital architectures, with a penalty due to the insertion loss. To illustrate this phenomena, two generalized equivalent circuits are proposed are a numerical example is presented.

Design of Broadband 9×9 Butler Matrix and its Extension for Multibeam Application

In this brief, a broadband 9×9 Butler Matrix (BM) and its extension for multibeam antenna array (MAA) application are presented. Based on the configuration of 3×3 beamforming network (BFN) comprised of three couplers and two 90∘ phase shifters, the topology of 9×9 BM is built, which can provide in-phase signals at output ports. And a broadband 9×9 BM is implemented to verify the design by adopting broadband components. The results indicate that the designed broadband 9×9 BM achieves equal power division and 9 uniformly distributed progressive phases (PPs) between output signals in a relative bandwidth of 40% when the 9 input ports are excited, respectively. And the fabricated 9×9 BM is applied in MAA for producing 9 beams including a boresight beam. In addition, according to the design method of 9×9 BM, the topology of the extended 27×27 BM is built and presented, which validates that an extended BM with higher order can be realized by the design method, and the extended BM can also provide in-phase signals at output ports.

A continuous transverse stub array with parabolic reflector for [formula omitted]-band multibeam application

This paper proposes a compact continuous transverse stub (CTS) array that utilizes substrate integrated waveguide (SIW) technology. The CTS array includes six radiation slots and is powered by a novel linear source generator (LSG) with a parabolic reflector located on the bottom layer. The LSG converts the input wave into a planar wave that is subsequently coupled to the parallel-plate waveguide (PPW) of the CTS array through a coupling slot. By utilizing different input ports, the CTS array can produce planar waves in various directions, allowing for the production of beams with different pointing. The CTS array comprises four-layer substrates with a total thickness of only 0.24λ0. The measurement results show that the reflection coefficient of the array is below -10.9 dB in the operating range of 33-37 GHz. The array scanning angle theta can be up to about ±38°at the center frequency of 35 GHz, with a maximum gain of 20.9 dBi. When using the middle port feed, the measurement gain is superior to 20.1dBi and the radiation efficiency is above 87.1% in the 33-37 GHz range. Simulation and measurement results are in agreement, demonstrating that the proposed CTS array is suitable for multibeam applications in the Ka-band.

Miniaturized Pattern-Reconfigurable Multimode Antennas With Continuous Beam-Steering Capability

In this paper, two miniaturized multi-mode pattern steering antennas for Internet of Things (IoTs) applications are proposed. A compact multi-mode cavity functions both the hybrid and radiator. A continuous 360° pattern scanning in the azimuth plane is controlled by the amplitude and phase of three excitation ports. The first design achieves the smallest size with TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> modes. In contrast, the second design has improved impedance bandwidth and mode isolation by introducing TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> and high-order TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> modes. Eight dipole chokes are attached to the cavity for surface current suppression. This approach eliminates the unwanted patch mode radiation. The antennas support multibeam applications with digital beamforming and analog beamforming with the 0°/180° phase switch and variable gain amplifier (VGA). The direction of arrival (DOA) can be estimated by directly measuring the amplitude and phase of the receiving signal. No full phase shifter and signal classification algorithm are required. The prototypes are fabricated and measured at 2.4 GHz. The diameters of the two antennas are 0.4 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and 0.9 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . The achieved antenna size is very miniature as shown by the literature comparison. The radiation and DOA performance is evaluated. The peak system efficiency is better than 60% after calibration and a good DOA estimation result is obtained.

Design of Modified Butler Matrix Based on N-Way Directional Coupler and Its Multibeam Application

In this article, a new approach to designing a modified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N^{2} \times N^{2}$ </tex-math></inline-formula> Butler matrix (BM) based on an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -way directional coupler (NWDC) is presented. First, by introducing phase shifters and ingeniously arranging the input and output ports, the topologies of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9 \times 9$ </tex-math></inline-formula> BM based on a three-way directional coupler (3WDC) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16 \times 16$ </tex-math></inline-formula> BM based on a four-way directional coupler (4WDC) are built. Next, according to the design method of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9 \times 9$ </tex-math></inline-formula> BM and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16 \times 16$ </tex-math></inline-formula> BM, the topology design of modified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N^{2} \times N^{2}$ </tex-math></inline-formula> BM based on NWDC is developed. Considering whether there are progressive phase differences (PPDs) of 0° at output ports, the two cases in which <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> is odd and even are discussed. Finally, in order to verify the design method, a prototype of microstrip <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9 \times 9$ </tex-math></inline-formula> BM working at 5.5 GHz is designed, fabricated, and measured. The results show that the designed microstrip <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9 \times 9$ </tex-math></inline-formula> BM achieves equal power division and nine different PPDs among the output signals when the nine input ports are excited, respectively, which meets design expectations. And it is used as a beamforming network (BFN) for a multibeam antenna array (MAA) to generate nine radiation beams. And then, the design method of modified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N^{2} \times N^{2}$ </tex-math></inline-formula> BM is validated by the implementation of microstrip <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9 \times 9$ </tex-math></inline-formula> BM. And the design method of the modified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N^{2} \times N^{2}$ </tex-math></inline-formula> BM provides a novel approach for BFN technology when massive input and output ports are required.

Design and Extension of Modified Butler Matrix Based on Three-Way Directional Coupler and Its Multibeam Application

A new topology of modified Butler matrix (BM) based on three-way directional coupler (TWDC) is proposed in this brief. The two TWDCs are regarded as two submatrices, by alternately arranging the output ports of the two submatrices and introducing a front network consisting of 3dB/90∘ hybrid couplers, 3dB power divider and phase shifters, a topology of modified five-input six-output (5×6) BM is constructed. In order to verify the design method, a prototype of microstrip 5×6 BM operating at 5.5 GHz is implemented and it is used as a beamforming network (BFN) for multibeam antenna array (MAA) to generate five radiation beams including a boresight beam. The measured and simulated results coincide well with each other. And according to the design method, a topology of extended 9×12 BM is designed based on the 5×6 BMs, which validates the capacity of building a modified BM with a higher number of the input and output ports.

Study of a Toroidal Lens

This letter presents a study of a toroidal-shaped lens following a Luneburg-like distribution of refractive index intended to multibeam radio frequency front ends. Due to its toroidal shape, this is a new model of lens that does not present any blind spot, as an opposite to any other kind of either spherical or cylindrical lens when adding both antennas and associated electronics. A sidelobe level reduction is proposed based on interface intrinsic impedance matching with magnetic–dielectric composite materials. It also proposed a set of numerical approximations of the main electromagnetic parameters, such as the half-power beamwidth in both the E- and H-planes, and the sidelobe level, and the directivity, in order to provide some basic guidelines for such a lens project. Given the new shape, the impacts of the curvature of the torus on the radiation pattern are also carried out. In order to prototype a toroidal lens with 3-D printing technology, a material has been fully characterized electromagnetically considering infill ratio variations in some effective dielectric constant models for multimaterial mixtures. The resulting toroidal lens has been characterized in far field, demonstrating a good agreement with the model and confirming its great potential for multibeam applications.

Design of broadband microstrip three‐way directional coupler for multibeam antenna application

AbstractIn this letter, a design of broadband microstrip three‐way directional coupler (TWDC) is presented. The broadband performance of the microstrip TWDC is realized by the method of cascading multi‐section. The broadband TWDC is designed to achieve equal power division and −120°, 0°, and +120° phase differences between output signals. To verify the broadband design, a prototype of three‐section microstrip TWDC operating at C‐band is designed, fabricated and measured. The measured results show that the power division error of the designed broadband TWDC is less than ±0.7 dB and phase error is less than ±12° at a relative bandwidth of 16%. To verify its performance in multibeam application, the designed TWDC is used as a beamforming network for multibeam antenna array to generate three orthogonal beams.

Wideband Conformal Transmitarrays for E-Band Multi-Beam Applications

Wideband conformal transmitarrays at E-band are developed for multibeam applications in this article. A triple-layer element with double split rings is presented for wideband transmissions, achieving a 360° continuous phase variation range at 74 GHz with less than 2.3 dB transmission loss. A comprehensive design methodology of multibeam conformal transmitarrays is demonstrated for various platforms with different curvatures. To validate the theoretical analysis, conformal transmitarrays with two different curvatures are designed, fabricated, and measured. Multiple radiation beams are realized between ± 30° and ± 45° for the two prototypes, respectively. Good agreement is obtained between simulation and measurement. The 3 dB gain bandwidths are 30% from 66.5 to 90 GHz, and 27.8% from 68 to 90 GHz for the two designs, respectively, covering the entire E-band.

Design of millimeter wave dual‐polarized multibeam antenna array with a boresight beam

A design of millimeter wave (mm-wave) dual-polarized multibeam antenna array (MAA) with a boresight beam is presented. In order to generate a boresight beam, a 5 × 6 Butler matrix based on three-way directional couplers is designed as the beamforming network, which achieves equal power division and −60°, +120°, 0°, −120°, +60° progressive phase differences among the output ports when the five input ports are excited, respectively. By four-layer design, the two 5 × 6 BMs for horizontal polarization (HP) and vertical polarization (VP) are constructed. The patch is used as radiator element, and the HP and VP wave are excited by aperture coupling and microstrip feed, respectively. A prototype is fabricated and measured to verify the design. The measured results show that the designed mm-wave dual-polarized MAA can generate five radiation beams including a boresight beam and the five beams with HP and VP cover the range of ±50° at 28 GHz. In addition, the designed mm-wave dual-polarized MAA can be a potential option for mm-wave multibeam application.

Millimeter-Wave Fully Integrated Dielectric Resonator Antenna and Its Multi-Beam Application

To address the issues of the inconvenient fabrication and integration for millimeter-wave (MMW) dielectric resonator antennas (DRAs), a new configuration is proposed. First, a dielectric resonator with artificial electromagnetic boundaries is implemented by introducing the electromagnetic band-gap structure along the four side-wall boundaries of a certain dielectric region on a printed circuit board. The electromagnetic bandgap (EBG) structure is constructed using a printed array of periodic upside-down mushroom-type unit cells. The resonant-mode analysis reveals that the proposed DR can support conventional dielectric resonator modes and dense dielectric patch (DDP) cavity modes simultaneously. To excite the DR, a substrate-integrated gap waveguide transmission line is embedded in the proposed structure for implementing a fully integrated DRA. For demonstration, a fully integrated dielectric resonator antenna (FIDRA) operating at 31 GHz is designed. Simulated results show that the antenna offers an 11.5% −10 dB impedance bandwidth (29.6 to 33.2 GHz), in which a peak gain of 7.85 dBi is obtained. As an extension, a multi-beam antenna array composed of a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 \times 4$ </tex-math></inline-formula> FIDRA antenna array and a SIGW <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \times 4$ </tex-math></inline-formula> Butler matrix is designed and fabricated. The experimental results verified the effectiveness of the proposed configuration in integrating the DRA and feeding network.

A Wideband 3-D-Printed Multibeam Circularly Polarized Ultrathin Dielectric Slab Waveguide Luneburg Lens Antenna

This letter presents a wideband three-dimensional (3-D)-printed circularly polarized (CP) ultrathin dielectric slab waveguide (DSW) Luneburg lens (LL) with multibeam application in X-band. The characteristic that DSW supports TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> waves to pass through with different phase constants is used to generate 90° phase difference to compose CP wave for the proposed structure. To prove the point, the prototype antenna is fabricated by 3-D printing and measured. The results show that the proposed LL supports multibeam application with 11 beams covering ±60° range in azimuth plane, and the 3 dB axial ratio bandwidth for multibeam antenna is 23.5% with reflection coefficient lower than −10 dB and gain higher than 13.7 dBi. The measured results show good coincidence with simulated ones.

A wide‐angle scanning Luneburg lens antenna

The Luneburg lens is an effective way to implement multibeam antennas. However, the existing planar Luneburg lens configuration usually can only provide a relatively narrow scanning range. To deal with this problem, a Luneburg lens consisting of one dielectric cylinder and nine dielectric rings is proposed. It can be easily fabricated using low cost ABS material through 3D printing technology. The lens is placed between two metal plates which have an additional flare structure to enhance the antenna gain. To effectively excite the lens for multibeam applications, 9 magneto electric dipoles are utilized. For validation, a wide-angle scanning planar Luneburg lens antenna operating at 35 GHz was designed, fabricated and measured. A good agreement between simulation and measurement can be observed. At the center frequency, a wide scanning coverage of 172° can be obtained with a gain variation less than 1.6 dB.

A Dual Slant-Polarized Cylindrical Array of Tightly Coupled Dipole Antennas

This study proposes a design of a low-profile ultra wide-band cylindrical antenna array with plus/minus 45-degree dual polarization. The proposed compact cylindrical antenna array produces an omnidirectional radiation pattern in the azimuth plane to cover all directions. It consists of <inline-formula> <tex-math notation="LaTeX">$20\times 4$ </tex-math></inline-formula> dual-polarized elements within a diameter of 131 mm and a height of 116 mm. The array elements are tightly coupled slant-polarized wideband dipole antennas, and hence, rotational symmetry of radiation patterns in the horizontal plane is achieved for the two orthogonal polarizations. Furthermore, a metasurface structure has been designed and placed over the interconnected array elements to achieve ultrawideband capabilities. The proposed array provides less than &#x2212;10 dB reflection coefficient over a frequency band between 1.7 GHz and 5.9 GHz. The cross-polarization discrimination (XPD) is 15 dB at boresight in the azimuth plane. The electromagnetic characteristics of the cylindrical array and its corresponding planar array before bending have been evaluated and compared via simulations, and verified by measurements. The compact size, lightweight, and printable design of the proposed antenna array enable low-cost manufacturing and ease of installation. The proposed array design overcomes many challenges encountered in wide-band MIMO systems by covering the entire sub-6 GHz band while providing wide 360-degree coverage in the azimuth plane, hence, supporting multibeam applications.

Design of compact wideband Rotman lens for 5G multibeam application

In this paper, a compact broadband Rotman lens beamforming network based on equal optical path difference is proposed. The beamforming network is intended for applications in a multi-beam antenna array of 5G millimeter-wave (mm-wave) communication. Firstly, the theoretical design of the Rotman lens is introduced in detail. A power divider is used to replace the standard single-port feeding mode to generate a high-directional beam, reducing the scattering of the lens’ internal energy and the energy loss at adjacent ports. The Chebyshev multi-stub matching converter is used to optimize the original tapered array output port. To ensure a wide frequency band, the original matching port size is reduced, and the overall size of the lens is reduced by 20%. Measurement results of the improved model, show that the working frequency band of the lens is 16.5−33.8 GHz, of which S11 is better than 15 dB at 17.2−32.0 GHz, and the scanning angle is ±30°. The lens has a simple and compact structure, can effectively provide a stable phase difference signal for adjacent array elements, and achieve the goal of 5G millimeter-wave array multi-beam.

Compact SIW 2-D Butler Matrix and Its Multibeam Application

This letter presents a compact 2-D Butler matrix (BM) realized by multilayer substrate integrated waveguide (SIW) technology. The 2-D BMs in the open literature suffer from either bulky size or poor integration with the radiation portion. Facing this issue, a new SIW 2-D BM is developed and realized in planar configuration easily integrated with the slot antenna array. The key point of this letter is to design planar 2-D components, including 2-D couplers, 2-D crossovers, and 2-D phase shifters, of the proposed SIW 2-D BM, which can perform coupling, intersection, or phase shifting in both E- and H-planes. The proposed SIW 2-D BM also has the merit of ease integration with radiation portion and it is used to build a compact 2-D multibeam antenna in this letter. Simulation, fabrication, and experiments are conducted to verify the performance of the realized 2-D multibeam antenna.