A 2×2 integrated filter antenna array

In the practical application of aircraft, there may be situations when it is not possible to resolve radar target signals in the measurement channels of range, speed and angular coordinates in the on-board radar system. In these situations, it is advisable to use angular estimation procedures with super-resolution in the onboard radar system. Various methods and algorithms of angular estimation with super-resolution are known, each of which has its own advantages and disadvantages. At the same time, there is no information in the available scientific and technical literature about the algorithms of angular estimation with super-resolution used in the onboard radar system, knowledge of which is necessary when designing promising onboard radar systems. The article systematizes and analyzes the methods and algorithms of angular estimation with super-resolution. The classification of methods of angular estimation with superresolution is given. The generalized information about the known one-dimensional and twodimensional methods and algorithms of angular estimation is given. The algorithms proposed for use in flat antenna arrays, concentric ring antenna arrays, ring antenna arrays, round four-quadrant antenna arrays, flat antenna arrays with a total output signal are considered. It is noted that the features of the construction of radar homing heads include a reduction in the total number of information processing channels achieved by combining antenna elements into sublattices, the output signals of which are used to estimate the angular coordinates of radiation sources. The specificity of such antenna arrays is that the antenna sublattices have radiation patterns that are narrower than those of weakly directed antenna elements. In addition, the distance between the antenna modules can significantly exceed the distance between the antenna elements in a conventional antenna array and at the same time significantly exceed the wavelength size. To determine the possibilities of applying in practice the algorithms of angular two-dimensional estimation with super-resolution considered in the article in the onboard radar system, it is necessary to conduct special studies.

In the practical application of aircraft, situations are possible when in the on-board radar system (onboard radar) it is not possible to resolve the signals of radar targets in the channels for measuring range, velocity and angular coordinates. In these situations, it is expedient to use superresolution angular estimation procedures in the radar. There are various methods and algorithms for angular estimation with superresolution, each of which has its own advantages and disadvantages. At the same time, in the available scientific and technical literature there is no information on the superresolution angular estimation algorithms used in the radar, the knowledge of which is necessary in the design of promising radar. The article systematizes and analyzes methods and algorithms for angular estimation with superresolution. A classification of methods of angular estimation with superresolution is given. Generalized information about known one-dimensional and two-dimensional methods and algorithms of angular estimation is presented. The algorithms proposed for use in planar antenna arrays (ARs), concentric annular antenna arrays, ring antenna arrays, circular four-quadrant ARs, planar ARs with a total output signal are considered. It is noted that among the features of the construction of an on-board radar is the reduction in the total number of information processing channels, achieved by combining antenna elements into subarrays, the output signals of which are used to estimate the angular coordinates of radiation sources. The specificity of such antenna arrays is that the antenna subarrays have directional patterns that are narrower than those of weakly directional antenna elements. In addition, the distance between antenna modules can significantly exceed the distance between antenna elements in a conventional antenna array and, at the same time, significantly exceed the wavelength size. To determine the possibilities of practical application of the algorithms of angular two-dimensional estimation with superresolution in an on-board radar with a modular AA, considered in the article, special studies are required.

This paper discusses the comparative effect of Electromagnetic Band Gap (EBG) structures on two element Microstrip antenna array. The dielectric substrate used is FR-4 glass epoxy with dielectric constant 4.2 and loss tangent 0.0245. The conventional antenna array is resonating at a frequency of 5.53 GHz with a mutual coupling of -17.83 dB. The first proposed antenna array with square slot EBG structure in the ground plane and fractal patch EBG structure on the surface produces a mutual coupling of -50.21 dB and a gain of 8.78 dB at 5.53 GHz. The second proposed antenna array with star slot EBG structure in the ground plane and diamond patch EBG structure on the surface produces a mutual coupling of -51.63 dB and a gain of 7.20 dB at 5.53 GHz. Both the proposed antenna arrays are producing appreciable decrease in back lobe radiation. The antenna arrays are designed using Mentor Graphics IE3D software and measured are obtained using vector network analyzer.

A high isolation, high gain and compact patch antenna arrays that operates in 11.4–11.78 GHz by using fractal defected ground structure (Fractal-DGS) is designed. Performance of the antenna arrays, such as isolation and radiation, are simulated and compared with conventional patch antenna array without Fractal-DGS. As is presented in this paper, the mutual coupling is −33dB at working frequency, it reduces 13dB compared with the traditional antenna array. And the radiation direction is better than conventional antennas too. Higher isolation and stable directional radiation pattern make this antenna array a better choice for millimeter wave communication system.

Design for radiation broadside direction using half-width microstrip leaky-wave antenna array

The integration of advanced techniques, like smart signal processing algorithms, in conventional antenna array has led to the emergence of more sophisticated antennas which are, today, called smart antennas. This specific kind of antenna array has two basic functions; direction of arrival estimation and beamforming. This paper investigates the performance of Direction-of-Arrival (DoA) estimation of the Minimum-norm algorithm and its derivative Root-min-norm. In order to improve the performance of these two DoA algorithms, a simple modification related to the signal used by the antenna array has been proposed. The performance of the algorithms has been evaluated for a uniform linear array. The simulation results show that the performance of the algorithms improves with the proposed modification.

In time-modulated antenna arrays (TMAAs), as a result of periodical switch-on and switch- ofi of the antenna elements, including operating frequency (termed as center frequency) signal, sideband signals are appeared at either sides of the center frequency in integer multiples of the modulation frequency. In this paper, it is shown that without using phase shifters, just by suitably controlling the on-time instants (OTIs) and on-time durations (OTDs) of a time-modulated linear antenna array (TMLAA) elements, simultaneously, along with a pencil beam pattern at the operating frequency, a shaped beam pattern can be obtained at both the flrst positive and negative harmonics of the time- modulation frequency. The important advantage of such a technique is that realization of multi-beam pattern in conventional antenna array (CAA) system generally requires complex feed network, whereas by using simple radio frequency (RF) switching circuit in the feed network of TMLAA, by virtue of the properties of harmonic radiations, synthesis of a shaped pattern at either (positive or negative) harmonic results in generating the same pattern in its opposite harmonic, and the synthesized patterns at difierent harmonics can be simultaneously used as independent communication channels. By employing a difierential evolution (DE) based optimization method, numerical results for a 16-element TMLAA with uniform excitation show that in conjunction with a pencil beam pattern at the center frequency, a ∞at-top or a cosec square pattern at flrst positive and negative sidebands of side-lobe levels (SLL) i20dB can be synthesized by suppressing the higher sideband level (SBL) to below i10dB.

This paper presents the review of the study on four dimensional (4D) antenna arrays, a type of antenna arrays which introduce a fourth dimension time - into conventional antenna arrays. The analytical theory and some numerical simulation results on their applications are presented

A novel two-element MIMO (Multiple-Input-Multiple-Output) antenna with THz radiation for next-generation communication networks is designed and analysed in this paper. The antenna is constructed using graphene-thin films developed on a polyimide substrate. Each element in the MIMO scheme consists of a series-fed radiating element that is structurally modified to yield quad-band radiation centred around 0.18, 0.36, 0.54, and 0.68 THz, with fractional bandwidths (at a −10 dB reflection coefficient) of 13.2%, 10.3%, 8.62%, and 7.4%, respectively. The conventional square patch-based series-fed antenna array is loaded with bow-tie slots, and the transmission lines connecting the patch radiators are optimised to realize the four frequency bands with |S11| ≤ −10 dB. The electrical size of the designed antenna is 0.383λeff × 0.173λeff, and the inherent inter-port isolation exceeds 30 dB in all realised frequency bands. The antenna exhibits directional radiation characteristics, offering precision communication with directivity and gain greater than 8 dBi and 4 dBi, respectively. The realized MIMO antenna array is subjected to performance evaluation under different channel conditions. The analysis suggests that the proposed array is a promising space-saving solution with miniaturized configuration for next-generation wireless sensor networks with nano-sensors designed for Internet of Things (IoT) communications that demand high data rate, good throughput and improved coverage through enhanced antenna radiation properties such as gain and efficiency.

A new method and tool design for borehole compensated electromagnetic propagation resistivity logging while drilling (LWD) are presented. The method provides borehole compensated resistivity measurements at multiple depths of investigation using a shorter antenna array than existing compensation methods. The compact array is typically 40% shorter than conventional antenna arrays for borehole compensated measurements, resulting in a shorter, lower cost bottom hole assembly (BHA). This paper presents the theoretical basis of the compact array design, as well as electromagnetic modeling results demonstrating performance in downhole conditions of interest. Results from field tests of a downhole tool are also presented. The compact array design has been applied to create a shorter, lower cost resistivity logging while drilling collar. The three resistivity measurements enable determination of true resistivity (Rt), diameter of invasion, and flushed zone resistivity (Rxo) while drilling, geosteering, and formation evaluation in horizontal or deviated wells where application of wireline tools is difficult. The initial downhole antenna array design is some 44% shorter than equivalent conventional antenna arrays for borehole compensated measurements. Electromagnetic modeling results are presented for the three-receiver and two-transmitter antenna array to demonstrate performance of the shallow, medium, and deep resistivity outputs from phase-difference measurements. Modeling and field test data are used to show equivalent performance of the compact array to existing compensated antenna arrays in rugose boreholes and at bed boundaries. Modeling results are also presented which demonstrate the limitations and advantages of multi-frequency operation. Test data for a new method for compensation of electronics error are also shown. The paper presents a new approach to LWD borehole compensated resistivity methods that reduces the overall length of the antenna array and associated cost. The compact antenna array provides improved invasion profiling and determination of true resistivity when compared to existing borehole compensated array designs.

ABSTRACTA quad reconfigurable antenna using 2 × 1 array of rectangular patches is investigated in this article starting from conventional microstrip antenna array with two elements. It offers reconfigurability for frequency, pattern, gain, and polarization in the same design. Modifications are added for conventional 2 × 1 antenna array to get multifunction reconfigurable antenna to change in frequency, pattern, gain, and polarization, simultaneously. Frequency reconfigurability is achieved between 1.88 and 2.45 GHz, the main beam direction of radiation pattern rotates between 0 and 30 degree (elevation angle). The proposed design offers antenna gain that can be switched between 5.7 and 7.8 dBi. Also, this design reconfigures between linear and circular polarization at 2.45 GHz. The proposed design is simulated using the CST Microwave studio 2012. The antenna array is fabricated using thin film photolithographic technique. The scattering parameters are measured using vector network analyzer E8719A. Measurements and simulations show good agreement. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2876–2883, 2015

Conventional antenna array 3-D inverse synthetic aperture radar (ISAR) imaging method does imaging by first carrying out ISAR imaging for all the different antennas and then using array direction of arrival (DOA) estimation on every scatterer to get the position of that scatterer. The aperture formed by the target's motion is used to separate the scatterers, and the antenna array aperture is used for position measurement. In this letter, a 3-D imaging method based on a combination of sparse array beamforming and ISAR imaging is proposed, where 3-D images are formed by space-time match filtering. The estimation of the target's rotation parameters is also given. Simulation results have shown the effectiveness of the proposed methods.

Here a lightweight antenna array is designed and fabricated for a Ka‐band phased array antenna. From the perspective of advanced space‐borne engineering practice, a Kagome lattice structure is proposed for the lightweight antenna array applications and the representative configurations of the proposed lattice structure is fabricated via selective laser melting (SLM). Experiment is performed to estimate the electrical performance with the featured structure. Compared with the conventional antenna array, the proposed one has 69% less weight, identical measured radiation patterns, and good electrical performance. The results demonstrate the great potentials for other readily customized lightweight phased array antenna applications.

Space-time adaptive processing (STAP) for range-dependent clutter rejection in airborne radar is considered. Indeed, radar antenna architectures or configurations that are different from the conventional uniform linear antenna array (ULA) and side-looking (SL) configuration have consequences on the clutter properties. The authors here investigate the use of Taylor series expansions (TSEs) of the space–time covariance matrix in the classical sample matrix inversion (SMI) STAP method in order to mitigate the range non-stationarity of the clutter and they compare it to the derivative-based updating (DBU) already proposed in the literature. The authors also propose a new algorithm based on a TSE of the clutter plus noise subspace in conjunction with the eigencanceler-based (EC) STAP, which improves the performance in term of signal-to-interference plus noise ratio (SINR) loss, compared to the DBU method. In this study, the particular cases of a ULA and a uniform circularly curved antenna (UCCA) array in SL and non-SL monostatic configurations as well as a ULA in some bistatic configurations are considered for the test and the comparison of the presented algorithms.

This paper presents a general, theoretical investigation on the radiation of an infinite, one-dimensional antenna array, which is phased to radiate electromagnetic fields focused in an arbitrary location. The analysis is performed on the wave phenomena of the Floquet wave modes obtained via the Poisson sum formula. Asymptotic techniques were employed to evaluate the resulted integral in terms of ray optical fields. The analysis may reduce to the case of a conventional phased antenna array with radiation focused in its far zone, and exhibits consistent phenomena. Theoretical investigations as well as numerical illustrations are presented.