Two-dimensional Beam Pattern Research Articles

On the 2D Beampattern Optimization of Sparse Group-Constrained Robust Capon Beamforming with Conformal Arrays

To overcome the problems of the high sidelobe levels and low computational efficiency of traditional Capon-based beamformers in optimizing the two-dimensional (elevation–azimuth) beampatterns of conformal arrays, in this paper, we propose a robust Capon beamforming method with sparse group constraints that is solved using the alternating-direction method of multipliers (ADMM). A robustness constraint based on worst-case performance optimization (WCPO) is imposed on the standard Capon beamformer (SCB) and then the sparse group constraints are applied to reduce the sidelobe level. The constraints are two sparsity constraints: the group one and the individual one. The former was developed to exploit the sparsity between groups based on the fact that the sidelobe can be divided into several different groups according to spatial regions in two-dimensional beampatterns, rather than different individual points in one-dimensional (azimuth-only) beampatterns. The latter is considered to emphasize the sparsity within groups. To solve the optimization problem, we introduce the ADMM to obtain the closed-form solution iteratively, which requires less computational complexity than the existing methods, such as second-order cone programming (SOCP). Numerical examples show that the proposed method can achieve flexible sidelobe-level control, and it is still effective in the case of steering vector mismatch.

Main lobe interference suppression by FDA-MIMO radar based on a novel log function frequency offset

Frequency diverse array (FDA), which can be combined with Multiple-input-Multiple-output (MIMO) to improve the performance of system, and the range information provided by FDA-MIMO radar provides a new idea for suppressing main lobe interference. However, the periodicity of the angle-range two-dimensional beam pattern also causes some safety hazards to the radar beamforming process. When the interference is located in the grating lobe of FDA-MIMO radar, the related algorithm of beamforming will appear serious distortion. The traditional nonlinear frequency offset method to remove the periodicity of the beam pattern will cause the problem of large main lobe width. In this paper, a new log function frequency offset is proposed, which can not only achieve the periodic removal of the FDA-MIMO radar beam pattern but also has a narrower main lobe bandwidth of 3dB compared with the traditional nonlinear frequency offset method

Two-Dimensional Beam Pattern Synthesis for Phased Arrays With Arbitrary Element Geometry via Magnitude Least Squares Optimization

In this paper, an optimization procedure for synthesizing shaped beams with an arbitrary geometry phased array system with real-time capability is presented. The algorithm involves a combination of an arbitrary extension of the Woodward-Lawson synthesis procedure with the magnitude least-squares optimization method. This simple combination significantly reduces the optimization time, enabling real-time beam shaping in response to changing requirements on beam shape or evolving geometry in distributed arrays. The technique places no restrictions on element positioning in all three spatial dimensions and is demonstrated to accurately reproduce the desired beam shape in both angular dimensions. The algorithm is demonstrated for multiple beam cases with a large, randomly generated array in computational simulation. The applicability of the algorithm to practical phased array hardware is also demonstrated using full-wave electromagnetic simulations and measurements of a realized arbitrary phased array system using a near-field scanner in an anechoic chamber.

200×200 µm2 structured light source.

3D structured illumination is important in high-speed 3D metrology where beam patterns are roughly categorized into multi-dot and fringe patterns. For example, large-scale multi-dot patterns are utilized for facial recognition in an iPhone X on the basis of an active stereo method, while fringe patterns are utilized in Grey code patterns or fringe projection profilometry including Fourier transform profilometry and the phase shifting profilometry, which is suitable for high-resolution measurement. Among these applications, the light sources include a combination of vertical-cavity surface-emitting lasers (VCSELs) and diffractive optical elements (DOEs), a projector, and so on. Recently, we demonstrated static arbitrary two-dimensional beam patterns without a zero-order beam from needle-tip sized integrable spatial-phase-modulating surface-emitting lasers (iPMSELs). Due to their compactness (they are one order of magnitude smaller than DOE), surface-emitting device, lack of zero-order beam, and ease of switching the beam patterns electrically, iPMSELs will be suitable as an ultra-compact light source for 3D metrology that not only downsizes the conventional light source but also contributes to 3D inspections in narrow spaces such as dental and endoscope examinations. In this context, we have examined two beam patterns (multi-dot and fringe) both without a zero-order beam by using the iPMSELs. In the former, we have demonstrated projection of large-scale dot patterns of more than 10,000 points, which is the same order of magnitude as points in a practical device from a 200×200-µm2 emitter. Since the emitter has approximately 1 mega scattering points, this structure enables 1-mega-pixel images in the wavenumber space, which are comparable to the images of a typical projector emitting several-mega-pixel images from several tens of centimeters. In the latter, we successfully shifted the fringe patterns, which is vital to applying the phase shifting profilometry, despite the superposition of the conjugate ±1st order beam patterns.

Two-Dimensional Beampattern Synthesis for Polarized Smart Antenna Array and Its Sparse Array Optimization

Polarized smart antenna array has attracted considerable interest due to its capacity of matched reception or interference suppression for active sensing systems. Existing literature does not take full advantage of the combination of polarization isolation and smart antennas and only focuses on uniform linear array (ULA). In this paper, an innovative synthesis two-dimensional beampattern method with a null that has cross-polarization for polarized planar arrays is proposed in the first stage. This method aims to further enhance the capability of interference suppression whose optimization problem can be solved by second-order conic programming. In the second stage, a new sparse array-optimized method for the polarized antenna array is proposed to reduce the high cost caused by the planar array that is composed of polarized dipole antennas. Numerical examples are provided to demonstrate the advantages of the proposed approach over state-of-the-art methods.

Cross-Configuration Substrate Integrated Waveguide Beamforming Network for 1D and 2D Beam Patterns

This paper presents the simulated and measured results of a dual-layer substrate integrated waveguide (SIW) beamforming network utilizing an 8 × 8 cross-configuration Butler matrix over a frequency range of 28.5 to 31.5 GHz. By arranging the input ports on the bottom SIW layer and employing dual-layer passband filters as a detachment point, the top SIW layer can be interchanged with the purpose of exploring one-dimensional and two-dimensional broadside beam patterns. Although Butler matrices are not typically utilized for beamforming in this configuration, two examples of interchangeable top layer arrays are demonstrated; the first being a 2 × 8 slot antenna array for 1-D scanning, and the second being a 2 × 4 center-slot array for 2-D scanning. Each of the beamforming network's simulated and measured 10 dB bandwidth is demonstrated over a range of 28.5 to 31.5 GHz. Additional design details and dimensions are specified for the aforementioned passband filter transitions, as well as for each of the slot antenna arrays.

Removal of surface-normal spot beam from on-chip 2D beam pattern projecting lasers.

Static arbitrary two-dimensional beam patterns have been demonstrated using on-chip size "integrable spatial-phase-modulating surface-emitting lasers," which use the band edge mode of a two-dimensional photonic crystal as an in-plane resonator, while the spatial phase of the lightwaves of the band edge mode are simultaneously modulated in a holographic manner by a local positional shift of holes from their lattice points. Meanwhile, the beam patterns include a spot beam in the surface-normal direction (0th-order beam), which corresponds to components of vertical diffraction of the band edge modes without spatial phase modulation. A promising method, used to remove the 0th-order beam, uses a structure that prohibits the vertical diffraction of band edge modes. For this purpose, we set the period of the virtual photonic crystal structure from the conventional Γ2 band edge to the Μ1 band edge, where vertical diffraction is prohibited. Moreover, the additional spatial phase modulation that cancels the in-plane component of the wavevectors of the lightwaves of the band edge modes at the Μ1 band edge are also imposed to output the beam patterns vertically. As a result, we successfully demonstrated two-dimensional beam patterns without a spot beam in the surface-normal direction.

Principle of beam generation in on-chip 2D beam pattern projecting lasers.

Integrable spatial-phase-modulating surface-emitting lasers, which utilize the band edge mode of two-dimensional photonic-crystals as resonators, project static arbitrary two-dimensional beam patterns from on-chip size. In this device, holes shifting from the lattice point of a two-dimensional photonic crystal provide spatial phase modulation to light waves, which form standing waves in the resonator. Thus far, the origin of the beam patterns has not been studied, especially the formation of subsidiary beam patterns against the designed beam pattern. In this work, we clarify the origin of beam patterns in two types of spatial phase modulating method, which impose in-plane shifting of holes according to circular and linear shift methods. Based on a theoretical study of spatial phase modulation, we reveal that the circular shift method provides a symmetric beam pattern, while the linear shift method causes an asymmetric beam pattern. Consequently, we demonstrated the asymmetric two-dimensional beam pattern by the linear shift method for the first time.

Using Side Scan Sonar Instrument for Seabed Identification with Pattern Discrete Equi Spaced Unshaded Line Array (Pdesula) Model

Side Scan Sonar (SSS) is a sonar system development instrument which has the capability to show the images of the two-dimensional surface of the seabed by contour conditions, topography, and the target simultaneously. The Beam Pattern Discrete–equi-spaced unshaded Line Array Method was used to compute the two-dimensional beam pattern which depends on the angle of the incoming sound waves from the axis of the array were accepted have been depending on the angle at which the sound beam array. This research was conducted in December 2016 in the Punggur Sea, Batam, Riau Islands-Indonesia, and its coordinate system is 104°08,7102 E and 1°03,2448 N until 1°03.3977 N and 104°08,8133 E, using Side Scan Sonar Tow C-Max CM2 fish instruments with a frequency of 325 kHz. The recorded results show that there are 7 targets, and Beam pattern of Discrete-Beam Equi-Spaced unshaded Line Array method in target 4 has the highest value in the directivity pattern is 21.08 dB. The results of the beam pattern model show that neither the central value at the incidence angle (o) of the Directivity Pattern (dB) were not at the 0 (zero) or the beam pattern central have been generated by the target 6 with incident angle -1.5° and 1.5°. And also based on the Discrete-method result Beam Equi-Spaced Unshaded Line Array method was discovered the sunken wreck. In addition, it has declined by 40 dB. The bottom sediment in the Punggur Sea was founded the highly concentrate of the sand.

Beam Calibration of Radio Telescopes with Drones

We present a multifrequency far-field beam map for the 5-m dish telescope at the Bleien Observatory measured using a commercially available drone. We describe the hexacopter drone used in this experiment, the design of the flight pattern, and the data analysis scheme. This is the first application of this calibration method to a single-dish radio telescope in the far-field. The high signal-to-noise ratio data allows us to characterize the beam pattern with high accuracy out to at least the fourth side-lobe. The resulting two-dimensional beam pattern is compared with that derived from a more traditional calibration approach using an astronomical calibration source. We discuss the advantages of this method compared to other beam calibration methods. Our results show that this drone-based technique is very promising for ongoing and future radio experiments, where the knowledge of the beam pattern is key to obtaining high-accuracy cosmological and astronomical measurements.

Frequency-dependent variation in the two-dimensional beam pattern of an echolocating dolphin

Recent recordings of dolphin echolocation using a dense array of hydrophones suggest that the echolocation beam is dynamic and can at times consist of a single dominant peak, while at other times it consists of forward projected primary and secondary peaks with similar energy, partially overlapping in space and frequency bandwidth. The spatial separation of the peaks provides an area in front of the dolphin, where the spectral magnitude slopes drop off quickly for certain frequency bands. This region is potentially used to optimize prey localization by directing the maximum pressure slope of the echolocation beam at the target, rather than the maximum pressure peak. The dolphin was able to steer the beam horizontally to a greater extent than previously described. The complex and dynamic sound field generated by the echolocating dolphin may be due to the use of two sets of phonic lips as sound sources, or an unknown complexity in the sound propagation paths or acoustic properties of the forehead tissues of the dolphin.

10.1007/s11755-008-1006-6

In this paper we simulate a deep multi-frequency zenith-field sky survey on RATAN-600 (the RZF survey). In our simulations we use the 1.4 GHz sky images obtained in the NVSS survey. We convolved NVSS images with the two-dimensional power beam pattern of RATAN-600 and obtain simulated 24-hour scans of sky transits at all wavelengths of the RZF survey. For the 7.6 cm wavelength we analyze the effect of the image area size on the results of the simulation. We estimate the accuracy of the determination of source fluxes on simulated scans and derive the distributions of the spectral indices of the sources. We use the simulated scans to clean real records of the RZF survey at 7.6 cm. The standard error of the residual noise at this wavelength is about 1 mJy.

Near field vector beam measurements at 1 THz

We have performed near-field vector beam measurements at 1.03 THz to characterize and align the receiver optics of a superconducting receiver. The signal source is a harmonic generator mounted on an X-Y translation stage. We model the measured two-dimensional complex beam pattern by a fundamental Gaussian mode, from which we derive the position of the beam center, the beam radius and the direction of propagation. By performing scans in the planes separated by 400 mm, we have confirmed that our beam pattern measurements are highly reliable.

A Low-Sidelobe, High Frequency Corrugated Feed Horn for CMB Observations

We have produced a prototype broadband, low-sidelobe conical corrugated feed horn suitable for measurements of the Cosmic Microwave Blackground (CMB) radiation in the frequency band 120–150 GHz. The antenna is a first prototype for the Low Frequency Instrument array in ESA's PLANCK mission, a space project dedicated to CMB anisotropy mesurements in the 30–900 GHz range. We describe the fabrication method, based on silver electro-formation, and present the two-dimensional antenna beam pattern measured at 140 GHz with a milimeter-wave automated scalar test range. The beam has good symmetry in the E and H planes with a far sidelobe level approaching –60 dB at angles ∼ 80°. An upper limit to the return loss was measured to be –21 dB.