End-fire Array Research Articles

Maximizing Gain of Endfire Arrays Based on Electrical Dipoles Using Spherical Harmonics

Maximizing Gain of Endfire Arrays Based on Electrical Dipoles Using Spherical Harmonics

End-fire optical phased array for passive beam steering on thin-film lithium niobate.

Autonomous driving technology has put forward higher requirements for sensors, including light detection and ranging. An optical phased array (OPA) is a viable solution, and numerous efforts have been made in this area. For its outstanding optical properties such as linear electro-optic effect and low optical loss, lithium niobate exhibits great potential and unique advantages in solid-state light-emitting arrays. Here we propose and experimentally demonstrate an end-fire optical phased array on a thin-film lithium niobate (TFLN) for passive beam steering. Furthermore, based on this work, we propose a three-line optical phased array to achieve a larger beam steering range. Our results provide a solution for the integrated optical phased array that shows potential in sensing and imaging with reduced size and power.

Effects of Mutual Coupling for Bistatic Airborne Radar with End-fire Array in Clutter Environment

Abstract The end-fire array is widely used in airborne radar systems for its specific physical configuration. However, mutual coupling is usually inevitable in the close-spaced end-fire array, which brings a great challenge for target detection in a clutter environment. In this paper, we investigate the effect of mutual coupling for the bistatic airborne radar with the end-fire array. Firstly, the signal model of the bistatic airborne radar with the end-fire array is presented. Then, the beam pattern and clutter model with mutual coupling are constructed. Furthermore, we analyze the clutter spectra with mutual coupling for different terrain types of the glistening zone. Finally, the simulation results validate the negative impact of the mutual coupling on target detection in clutter environment.

Reduced-Dimensional STAP Method for Nonstationary Clutter Suppression in Endfire Array Airborne Radar

Reduced-Dimensional STAP Method for Nonstationary Clutter Suppression in Endfire Array Airborne Radar

Low profile cavity-embedded ultra-wideband UHF array antenna with end-fire beams

A low profile, vertically polarized, ultra-wideband array antenna with end-fire beams operating in an ultra-high frequency (UHF) band is developed in this paper. The array antenna consists of 1×16 log-periodic top-hat loaded monopole antenna arrays and is feasible to embed into a shallow cavity to further reduce the array height. Capacitance is introduced in the proposed antenna element to reduce profile height and the rectangular top hats are carefully designed to minimize the transverse dimension. Simulated results show that when the antenna array operates in a frequency range of 300 MHz–900 ​MHz, the end-fire radiation pattern achieves ±45° scanning range in the horizontal plane. Then prototypes of the proposed end-fire antenna element and a uniformly spaced linear array (1×2) are fabricated and validated. The end-fire antenna array should be suitable for airborne applications where low profile and conformal scanning phased antenna arrays with end-fire radiations are required. This design is attractive for airborne platform applications that are used to search, discover, identify, and scout the aerial target with vertically polarized beams.

Wideband Wide-Angle Scanning Endfire Phased Array Antenna Based on Heterogeneous Beam Elements for Millimeter-Wave Mobile Terminals

Wideband Wide-Angle Scanning Endfire Phased Array Antenna Based on Heterogeneous Beam Elements for Millimeter-Wave Mobile Terminals

Millimeter-wave End-Fire Magneto-Electric Dipole Antenna and Array with Horizontal Polarization and Wide Bandwidth

Millimeter-wave End-Fire Magneto-Electric Dipole Antenna and Array with Horizontal Polarization and Wide Bandwidth

A Novel Quad-Band Branched Monopole Antenna with a Filter Suppressing Higher Order Modes

This paper proposes a novel quad-band branched monopole antenna with a filter. The proposed antenna has a simple configuration in which branch-elements are added to a basic configuration consisting of a mast and dielectric wires. The antenna is characterized by performances such as wideband impedance matching, gain stabilization, and gain enhancement. Wideband impedance characteristics satisfying the voltage standing ratio of less than 2 are obtained by exciting a parallel resonance at the lowest band and multi-resonance at high bands. The filter suppressing higher order modes is used for gain stabilization, so that averaged gains above 5 dBi are obtained at the quad-band. The antenna has a high gain of 11.1 dBi because the branch-elements work as an end-fire array antenna at the highest band. Furthermore, it is clarified that an operating frequency is switched by using a variable bandpass filter at the lowest band. Last, a scale model of the antenna is fabricated and measured, then the effectiveness of the proposed antenna is demonstrated.

Linear phased meta-material incorporated patch antenna array at sub-6 GHz for 5G base stations

ABSTRACT This article presented a four-element dual-band linear phased antenna array operating at sub-6 GHz. The single-element antenna was designed by mounting a double-negative single- layered Complementary Split Ring Resonator (SL-CSRR) on the patch and grounding with a rectangular slot and four SL-CSRR’s array; it was resonated at dual bands 3.43–3.56 GHz and 4.93–5.75 GHz and got size shrinkage of 80.45% with dimensions 0.35λx0.35λx0.028λ mm3. The proposed phased array antenna was resonated in 3.42–3.57 GHz and 4.86–5.74 GHz with central frequencies 3.49 GHz and 5.18 GHz, respectively, with respect to −10 dB impedance bandwidth. It was dimensioned with 0.35λx2.42λx0.028λ mm3. The isolation of > 16 dB, ECC < 0.1, DG ~ 10 dB, CCL < 0.15bits/s/Hz and MEG<-6 dB were achieved. The maximum gain of 8.4dBi and 10.4dBi and maximum efficiency of 81.14%, and 99.12% were achieved over the two resonated bands, respectively. The array antenna excited initially with 0° phase difference was radiated bi-directional beam focused to 0° and 180° in the pattern like a broadside array and with the change of phase difference, the structure capable to focus the beam to ± 90° like end-fire array at 3.49 GHz and it was capable to steer the beam to ± 48.6° at 5.18 GHz. These results demonstrated that the proposed phased array antenna is a good candidate to provide services at base stations for 5 G sub-6 GHz applications. The prototypes of the single-element antenna and four-element phased array antennae were fabricated and tested. The matching of simulation results with measurement one has a good commitment to similarity.

Performance Analysis of MVDR Beamformer Applied on an End-fire Microphone Array Composed of Unidirectional Microphones

Performance Analysis of MVDR Beamformer Applied on an End-fire Microphone Array Composed of Unidirectional Microphones

Superdirective Unidirectional Mixed-Multipole Antennas: Designs, Analysis, and Simulations

Highly directive antenna systems that will address the needs of space-limited Internet-of-Things devices and their NextG applications are in demand. Compact high-frequency high-directivity alternatives to complex, power hungry phased arrays are desired. Several compact, unidirectional mixed-multipole antennas (UMMAs) based upon mixtures of primarily dipoles and quadrupoles are reported. The simulated performance characteristics of these 28 GHz near-field resonant parasitic (NFRP) antennas, notably their large peak directivities and front-to-back ratios, are presented; they are all demonstrated to be superdirective while having attractive radiation efficiencies. Uniform endfire arrays of active closely-spaced equal-length idealized wire dipoles are exemplified as reference cases. The Rayleigh quotient (RQ) method typically used to determine their amplitude coefficients is extended for the first time to achieve unidirectional versions. Comparisons between these unconstrained and constrained RQ-designed arrays are made. While the performance characteristics of the single-source broadside-radiating UMMAs approach those of the reference arrays, a direct comparison of a realizable UMMA with the analogous unequal-length, non-uniformly-spaced idealized dipole array demonstrates its superiority. A two-element UMMA array that is scalable to a larger number of elements is also presented and shown to be superdirective, illustrating that the attractive properties of its individual elements are maintained even when mutual coupling occurs.

Beamforming Network Design Utilizing Node Microstrip Architectures for Dual-Polarized Endfire Millimeter-Wave Antenna Arrays

A node microstrip architecture is proposed for designing a compact Butler Matrix (BM) that is integrated with a dual-polarized endfire antenna array. The node microstrip architecture can be used to form a variety of compact 2 × 2 port networks including, but not limited to, couplers and crossovers. By concatenating the 2 × 2 port networks together, a compact BM with any number of ports can be formed. Using the proposed method, a compact 4 × 4 port BM operating in the millimeter wave band is designed and integrated with a dual-polarized endfire antenna array. The size of the compact BM is 2.1λ × 2λ and the size of the whole dual-polarized endfire antenna array with BM is 2.6λ × 4.8λ, which is smaller than traditional structures. The measured radiation pattern of the dual-polarized antenna array can achieve beam-scanning up to ±38° in the azimuth plane. The two beams in the dual-polarized endfire antenna array can also be independently steered. The optimized compact BM is potentially suitable for use in 5G wireless communication handsets.

Wideband Dual-Polarized Endfire Phased Array Antenna With Small Ground Clearance for 5G mmWave Mobile Terminals

A dual-polarized end-fire phased array antenna is presented for 5G mmWave mobile terminal applications. The antenna element combines a pair of top-hat dipoles with an open slot in two substrate layers. The dipole is excited by an open-ended substrate integrated waveguide (SIW) for vertical polarization, and the slot is coupled by a bent stripline for horizontal polarization. Both radiators can provide wide bandwidth, and share a small ground clearance of merely 1.6 mm. A 1 × 4 phased array is designed with an element spacing of 6 mm. Decoupling vias and decoupling slots are added between elements to improve port isolation. The simulated and measured overlapped bandwidth of the two polarizations are 21.4% and 14.6%, respectively. The isolation between any two ports is higher than 18 dB. The measured scanning beams of both polarizations are capable of covering ±42° within 3-dB gain variation.

A Compact Dual-Polarized Endfire Antenna Array for 5G Millimeter-Wave Terminal

This paper proposes a compact dual-polarized end-fire antenna array for 5G millimeter-wave (mmWave) application. The dual-polarized antenna unit is constructed by an open-ended substrate integrated waveguide (SIW) cavity for vertically polarized (VP) radiation and a broadband electric dipole for horizontally polarized (HP) radiation. By sharing the side walls of two neighboring SIW channels of the VP elements, the substrate integrated coaxial line (SICL) feeding structure for the HP element is achieved, thus a compact size of the final antenna array can be accomplished. To extend the bandwidth of the VP element, the quasi-TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode of the cavity and the slot mode of the end-fire aperture are adopted for the VP element. A corresponding linear array with four units is designed and fabricated. The common -10-dB impedance bandwidth covers from 24.8 GHz to 29.2 GHz. The maximum gain is 10.0 dBi for both polarizations, with an overlapped scanning coverage ranging from -41.5º to 45.5º at 27 GHz. The proposed design has a compact configuration, and a wide scanning range, which is alternative for 5G mmWave terminal application.

3-D SISL Feeding Network for 2-D Cavity-Backed Endfire Dipole Array at 24 GHz

This letter presents a 4×4 cavity-backed endfire dipole array with a novel feeding structure named as three-dimensional substrate integrated suspended line (SISL) feeding network (TSISLFN). Based on the SISL's structural superiority, air-filled substrate integrate waveguide (AF-SIW) can be vertically integrated with planar SISL in a self-packaged manner to form the TSISLFN. TSISLFN can be easily integrated with 2-D cavity-backed dipole array and the overall architecture can be realized through printed circuit board (PCB) technology. Then, the cost and weight of the whole structure are significantly reduced compared to the metal-waveguide counterpart. TSISLFN possess merits of self-packaging, low cost, and low loss. Both 2×2 and 4×4 cavity-backed endfire dipole arrays fed by TSISLFN are fabricated and measured. At 24.5 GHz, high efficiency of better than 91% and 79%, gain of 15.2 and 20.6 dBi are all obtained for the proposed 2×2 and 4×4 array respectively. Similar narrow beam widths in both E and H planes are also obtained.

Non-Uniform Metasurface-Integrated Circularly Polarized End-Fire Dipole Array Antenna

This paper presents a high-gain wideband circularly polarized antenna composed of an end-fire dipole array antenna integrated with a metasurface. The antenna consists of a two-layer cascaded non-uniform metasurface made up of 4 × 4 circular patches with cross-slots of unequal lengths placed above an end-fire dipole array antenna with an air gap between the structures. The end-fire dipole array antenna comprises four equally spaced dipole elements, and each dipole is connected to a parallel stripline printed on the front and back sides of the substrate. The metasurface, which is made up of a circular patch with 2 × 2 center patches that have a different radius than the outer patches, and the cross-slots of unequal lengths are used for the polarization conversion of a linearly polarized wave to a circularly polarized wave. The measured reflection coefficients for |&lt;i&gt;S&lt;/i&gt;&lt;sub&gt;11&lt;/sub&gt;| &lt; -10 dB yielded an impedance bandwidth of 25.6–31.8 GHz (21.5%), a 3-dB axial ratio (AR) bandwidth of 26.1–30.5 GHz (15.5%), a 3-dB gain bandwidth of 26.0–31.1 GHz (17.4%) with a peak gain of 11.0 dBic, and a radiation efficiency of more than 80% in the axial ratio bandwidth.

K-/Ka-Band Shared-Aperture Phased Array With Wide Bandwidth and Wide Beam Coverage for LEO Satellite Communication

A K-/Ka-band shared-aperture endfire phased array antenna is presented in this article. The antenna has the properties of dual wide bandwidths, orthogonal circular polarizations (CPs), wide beam coverage, and high isolation between the K-band and Ka-band channels. In this work, a new array topology is proposed to enhance the design freedom and the periodicity of the antenna array. Then, the filtering structures used to reflect the crossband coupled power also enhance the isolation between the K-band and Ka-band channels. The crossband mutual coupling is reflected and reradiated to generate the wideband CP beams. The high-order parallel plate waveguide (PPW) mode is suppressed to realize the wide CP beam coverage. The working bands at the boresight are 17.7–21.2 and 27.5–31.0 GHz, respectively. The polarizations are right-hand CP (RHCP) in K-band and left-hand CP (LHCP) in Ka-band. The maximal scan angles are ±60°. The axial ratios (ARs) are below 3 dB at boresight and below 5 dB when the beam scans to ±60°. The isolation between the K-band and Ka-band channels is higher than 40 dB.

Sustainable Design of Multiband Antenna for Wireless Communication Applications

This work emphasises sustainability as a crucial component of the design process and offers a novel approach to antenna design. A miniature circular microstrip antenna array with 1800 hybrid coupler operating at different modes of frequency, specifically aiming for multiband wireless communication is presented. The Circular patch, two element broad side array and end fire array structures are designed and analysed by using High Frequency Software Simulator (HFSS) software. Measured results are also presented for validating the simulated results.

A New Metasurface End-Fire Antenna Array Based on Yagi for 5G Applications

A novel end-fire wide-scanning metasurface antenna array for a millimeter wave operating at 28 GHz is proposed in this paper. The suggested antenna is considered as a low-cost device since it is printed on both sides of a single-layer FR-4 substrate with a thickness of 0.5 mm and a size of 44×13 mm2. On the top side of the cell phone PCB, eight Yagi antenna elements fed by microstrip lines have been used to form a linear array. The antenna gain and impedance matching are increased by placing a 5×5 metasurface composed of metallic H-shapes right in front of the Yagi array. This technique achieves a large bandwidth of 3.5 GHz from 26.2 to 29.7 GHz, and a high gain of 15.5 dBi, which is almost stable over a wide scanning angle. Finally, in order to understand the integration impact, the proposed antenna phased array has been covered by a casing. The simulation result demonstrates that there is no degradation effect for the entire assembly.

High power handling GaAs SP4T Switch-based Beam-Switching planar antenna module for 5G New-Radio FR2 applications

In this paper, a beam-switching antenna module for 5G New-Radio (NR) frequency range 2 (FR2) applications is proposed. The module is constructed with a single-pole-quadruple-throw (SP4T) switch featuring high power handling capability, low insertion loss, and higher isolation, which is integrated with a 4 × 4 Butler matrix and an end-fire antenna array for achieving beam switching characteristics. The system is realized on the Rogers RO3010 substrate which achieved a compact size of 4.67λ0 × 2.06λ0 × 0.031λ0 (f0 = 38 GHz) due to a higher integration level and demonstrated a decent impedance bandwidth of (15.78 %) 35–41 GHz with four beam patterns directing along + 14°, −40°, +49°, and −16°, respectively. The experimental results show an advantage in RF performance with high integration level which is promising for 5G NR n260 band communication applications.