Showing papers on "Reflective array antenna published in 2010"

Microstrip and printed antennas : new trends, techniques, and applications

Abstract: Preface. List of Contributors. Acknowledgments. 1 Numerical Analysis Techniques (Ramesh Garg). 1.1 Introduction. 1.2 Standard (Yee s) FDTD Method. 1.3 Numerical Dispersion of FDTD Algorithms and Hybrid Schemes. 1.4 Stability of Algorithms. 1.5 Absorbing Boundary Conditions. 1.6 LOD-FDTD Algorithm. 1.7 Robustness of Printed Patch Antennas. 1.8 Thin Dielectric Approximation. 1.9 Modeling of PEC and PMC for Irregular Geometries. References. 2 Computer Aided Design of Microstrip Antennas (Debatosh Guha and Jawad Y. Siddiqui). 2.1 Introduction. 2.2 Microstrip Patch as Cavity Resonator. 2.3 Resonant Frequency of Circular Microstrip Patch (CMP). 2.4 Resonant Frequency of Rectangular Microstrip Patch (RMP) with Variable Air Gap. 2.5 Resonant Frequency of an Equilateral Triangular Microstrip Patch (ETMP) with Variable Air Gap. 2.6 Input Impedance of a Microstrip Patch. 2.7 Feed Reactance of a Probe-Fed Microstrip Patch. 2.8 Radiation Characteristics. 2.9 Radiation Efficiency. 2.10 Bandwidth. 2.11 Conclusion. References. 3 Generalized Scattering Matrix Approach for Multilayer Patch Arrays (Arun K. Bhattacharyya). 3.1 Introduction. 3.2 Outline of the GSM Approach. 3.3 Mutual Coupling Formulation. 3.4 Finite Array: Active Impedance and Radiation Patterns. 3.5 Numerical Example. 3.6 Conclusions. 3.7 References. 4 Optimization Techniques for Planner Antennas (Rabindra K. Mishra). 4.1 Introduction. 4.2 Basic Optimization Concepts. 4.3 Real Coded Genetic Algorithm (RCGA). 4.4 Neurospectral Design of Rectangular Patch Antenna. 4.5 Inset-fed Patch Antenna Design Using Particle Swarm Optimization. 4.6 Conclusion. References. 5 Microstrip Reflectarray Antennas (Jafar Shaker and Reza Chaharmir). 5.1 Introduction. 5.2 General Review of Reflectarrays: Mathematical Formulation and General Trends. 5.3 Comparison of Reflectarray and Conventional Parabolic Reflector. 5.4 Cell Elements and Specific Applications: A General Survey. 5.5 Wideband Techniques for Reflectarrays. 5.6 Development of Novel Loop-Based Cell Elements. 5.7 Conclusion. References. 6 Reconfigurable Microstrip Antennas (Jennifer T. Bernhard). 6.1 Introduction. 6.2 Substrate Modification for Reconfigurability. 6.3 Conductor Modification for Reconfigurability. 6.4 Enabling Reconfigurability: Considerations for Reconfiguration Mechanisms. 6.5 Future Trends in Reconfigurable Microstrip Antenna Research and Development. References. 7 Wearable Antennas for Body Area Networks (Peter S. Hall and Yang Hao). 7.1 Introduction. 7.2 Sources on the Human Body. 7.3 Narrowband Antennas. 7.4 Fabric Antennas. 7.5 Ultra Wideband Antennas. 7.6 Multiple Antenna Systems. 7.7 Conclusion. References. 8 Printed Antennas for Wireless Communications (Satish K. Sharma and Lotfollah Shafai). 8.1 Introduction. 8.2 Broadband Microstrip Patch Antennas. 8.3 Patch Antennas for Multiband Wireless Communications. 8.4 Enhanced Gain Patch Antennas. 8.5 Wideband Compact Patch Antennas. 8.6 Microstrip Slot Antennas. 8.7 Microstrip Planar Monopole Antenna. References. 9 UHF Passive RFID Tag Antennas (Daniel Deavours and Daniel Dobkin). 9.1 Introduction. 9.2 Application Requirements. 9.3 Approaches. 9.4 Fabrication. 9.5 Conclusion. References. 10 Printed UWB Antennas (Zhi Ning Chen, Xianming Qing and Shie Ping See). 10.1 Introduction. 10.2 Swan Antenna with Reduced Ground Plane Effect. 10.3 Slim UWB Antenna. 10.4 Diversity Antenna. 10.5 Printed Slot UWB Antenna and Band-Notched Solutions. References. 11 Metamaterial Antennas and Radiative Systems (Christophe Caloz). 11.1 Introduction. 11.2 Fundamentals of Metamaterials. 11.3 Leaky-Wave Antennas. 11.4 Resonant Antennas. 11.5 Exotic Radiative Systems. References. 12 Defected Ground Structure for Microstrip Antennas (Debatosh Guha, Sujoy Biswas, and Yahia M. M. Antar). 12.1 Introduction. 12.2 Fundamentals of DGS. 12.3 DGS for controlling Microstrip Antenna Feeds and Front-End Characteristics. 12.4 DGS to Control/Improve Radiation Properties of Microstrip Patch Antennas. 12.5 DGS for Reduced Mutual Coupling between Microstrip Array Elements and Associated Improvements. 12.6 Conclusion. Appendix: A Brief DGS Chronology. References. 13 Printed Leaky Wave Antennas (Samir F. Mahmoud and Yahia M. M. Antar). 13.1 Introduction. 13.2 The Leaky Wave as a Complex Plane Wave. 13.3 Radiation Pattern of a Leaky Wave. 13.4 Examples of Leaky Mode Supporting Structures. 13.5 The Excitation Problem. 13.6 Two-Dimensional Leaky Waves. 13.7 Further Advances on a Class of Periodic Leaky Wave Antennas. References. Appendix I Preliminary Ideas: PTFE-Based Microwave Lamiantes and Making Prototypes. Appendix II Preliminary Ideas: Microwave Connectors for Printed Circuits and Antennas. Index.

Low-Profile PIFA Array Antennas for UHF Band RFID Tags Mountable on Metallic Objects

Abstract: Two PIFA array antennas, designed for UHF band RFID tags mountable on metallic objects, are presented in this paper. The proposed array antennas are fabricated on a very thin substrate with a thickness of 0.8 mm. The first array that has shorting pins placed at the outer edges of PIFAs is fed by two quarter-wavelength microstrip lines. This array has a simple feeding structure, which is its main advantage. Meanwhile, the second array has shorting pins located at the inner edges of PIFAs, and incorporating additional matching stubs into the quarter-wavelength microstrip lines is needed to achieve complex impedance matching, which can offer a broad bandwidth. By properly selecting the spacing between the PIFAs, an enhanced antenna gain and a good reading-range performance can be obtained for both array antennas. In addition, the two array antennas proposed are studied mounted on differently sized metallic plates. It is found that there is a negligible influence of the metal-plate size on the reading range is found for the second array antenna, which is superior to the first one.

New method for the time calibration of an interferometric radio antenna array

Abstract: Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative delays between the antennas can be detected and corrected for at each recorded event by measuring the phases at the beacon frequencies.

Design of multibeam scanning antennas with high gains and low sidelobes using gradient-index metamaterials

Abstract: Metamaterials, composed of artificial structures with subwavelength unit cells, can be fabricated to achieve gradually refractive indices. By designing the refractive indices properly, a gradient-index planar slab will transform spherical waves to plane waves. Using such a property, we propose a beam-scanning antenna with high gain and low sidelobes based on the gradient-index planar lens and a horn antenna, where the beam direction is controlled by the refractive-index distribution. When such four lenses are fixed together, we can get a four-beam scanning antenna with high gain and low sidelobes, in which each beam can be controlled independently. The gradient-index planar lenses can be realized using metamaterial structures.

High Permittivity Dielectric Rod Waveguide as an Antenna Array Element for Millimeter Waves

Abstract: Dielectric rod waveguide antennas of rectangular cross section have a number of advantages over conventional waveguide and horn antennas as an antenna array element. Dielectric rod waveguide antennas have relatively low cost, low losses, a broadband input match and a high packing potential. Additionally the radiation pattern of such antennas is almost frequency independent. In this paper the suitability of Sapphire rod waveguides for an antenna array is studied with simulations and prototype measurements at W band. Strong mutual coupling is observed when the elements are close to each other.

Analysis of large antenna systems

Abstract: The research presented in this thesis has been conducted within the framework of the Square Kilometre Array (SKA) project. SKA is a next generation radio telescope that will have a receiver sensitivity two orders of magnitude larger than the most sensitive radio telescope currently in operation. To meet the specifications, various low-cost low-noise actively beamformed receiving array antennas are being considered. A major problem in designing these systems is that the present-day commercially available electromagnetic solvers need an excessive amount of memory and simulation time to solve electrically large antenna problems. Moreover, it is essential to be able to analyze the receiver sensitivity of large antenna array systems to understand the sensitivity limiting factors. No dedicated commercial software tools exist that can analyze the receiver sensitivity of entire antenna systems specifically for radio astronomy. The thesis subject deals with two major challenges: (i) To accurately compute the impedance and radiation characteristics of realistically large and complex antenna arrays using only moderate computing power, particularly, of single and dual-polarized arrays of 100+ Tapered Slot Antenna (TSA) elements that are electrically interconnected. If the collection of these elements forms a subarray of a larger system, it is also of interest to analyze an array of disjoint subarrays. (ii) To characterize the system sensitivity of actively beamformed arrays of strongly coupled antenna elements. To address the above challenges, a conventional method-of-moments approach to solving an electric-field integral equation is enhanced using the Characteristic Basis Function Method (CBFM) to handle electrically large antenna problems. The generation of the associated reduced matrix equation is expedited by combining the CBFM with the Adaptive Cross Approximation (ACA) technique. Furthermore, because an overlapping domain decom270 Bibliography position technique is employed, Characteristic Basis Functions (CBFs) are generated that partially overlap to ensure the continuity of the current between adjacent subdomains that are electrically interconnected. While generating the CBFs, edge-singular currents are avoided by a post-windowing technique. Finally, a meshing strategy is proposed to optimally exploit the quasi-Toeplitz symmetry of the reduced moment matrix. The numerical accuracy and efficiency has been determined for numerous cases, among which a dual-polarized interconnected TSA array of 112 elements that has been fabricated and subsequently validated by measurements. The receiver system has been modeled by both a numerical and a semi-analytical method. The models account for a nonuniform brightness temperature distribution of the sky, mismatch effects, noise that emanates from amplifiers inputs and re-enters the system coherently through the mutually coupled antennas (noise coupling), beamformer weights, etc. Results are shown for a practical setup and design rules are derived which demonstrate that minimum receiver noise can be reached by noise matching the low-noise amplifiers to the active antenna reflection coefficient, rather than the passive one. Finally, it is demonstrated that the radiation efficiency of antennas is an important quantity that can degrade the system sensitivity severely. Nevertheless, a number of commercial software tools have shown to be inadequate as the computed efficiency exceeds 100%. A method is proposed which is numerically efficient and robust since it guarantees an efficiency below 100%.

Apparatus, system, and method for integrated modular phased array tile configuration

Abstract: An apparatus, system, and method are disclosed for phased array antenna communications. A phased array antenna tile includes a plurality of antenna elements. A beamformer module is integrated into the phased array antenna tile. The beamformer module is electrically coupled to each antenna element to process directional signals for the plurality of antenna elements. A plurality of cascadable connection points are disposed along a perimeter of the phased array antenna tile for connecting the phased array antenna tile to one or more additional phased array antenna tiles.

Miniaturized FSS and Patch Antenna Array Coupling for Angle-Independent, High-Order Spatial Filtering

Abstract: A new filter-antenna array design is presented in this article. This design approach can be employed to simplify the vertical integration of array beamformers. Basically, by placing a high-order filter, whose response is not sensitive to angle of arrival, in front of the array elements, the need for integrating bulky RF filters behind each element is eliminated. A new method for design of such phased-arrays is provided here in which the bandpass filters are removed, and instead, a metamaterial-based frequency-selective surface is placed directly over the antenna to perform the necessary filtering. The small spacing between the frequency-selective surface and the antenna, which is as low as ~ ?/10, results in creation of a compact filter-antenna design. The close proximity of the surface and the antenna is utilized to achieve a proper coupling between the selective surface and the array for high-order filtering without adversely affecting the gain or scan characteristics of the array. To test the performance of this approach, a 9 × 9-element patch-array is fabricated and measured at X-band. The array is then loaded with a 0.003"-thick, single-pole frequency-selective layer at a close distance on top. The measured received power as a function of frequency exhibits an improved frequency selectivity (better than the frequency-selective surface or the array alone). An improvement of about 50% reduction in the bandwidth and significantly higher frequency roll-off rate is observed once the array is covered with the metamaterial surface.

On Conditions for Constant Radiation Characteristics for Log-Periodic Array Antennas

Abstract: Wide frequency band antenna systems are required for many now and future applications, such as in radio astronomy and ultrawideband (UWB) technology. Constant radiation characteristics over a decade bandwidth are required for some of wide band applications, for example, feeds for reflector antennas in radio telescope. The log-periodic array antenna is one of the technologies for wideband antennas. In the present paper, an analysis on condition for constant radiation characteristics over wide bandwidth for a log-periodic array antenna is presented. From this condition, a guide rule for designing a wideband log-periodic array antenna is obtained. The Eleven antenna, a decade bandwidth log-periodic array antenna, is selected to illustrate the condition and verify the analysis in the paper.

Mimo radar apparatus and wireless communication method using the same

Abstract: Provided are a multiple-input multiple-output (MIMO) radar apparatus and a wireless communication method using the same. The MIMO radar apparatus includes a transmitter generating and transmitting different signals having a frequency modulated continuous wave (FMCW) form to a moving object as a target through transmitting antennas of a transmitting antenna array respectively, and a receiver receiving echo signals which are the signals transmitted through the transmitting antennas and reflected from the moving object through receiving antennas of a receiving antenna array respectively. At least one of the transmitting antenna array and the receiving antenna array is a planar antenna array.

Circular array of wideband 3D Vivaldi antennas

Abstract: This communication presents a novel 3D Vivaldi antenna array with 4∶1 bandwidth without the need for balun feeding. A circular array of 8 elements of this 3D Vivaldi antenna is simulated using the Array Scanning Method applied to Method of Moments. It is found that connecting the antennas provides a smoother frequency response. The array is well suited for wideband direction finding with good polarimetric sensitivity. Its calibration made easy by the circular symmetry of the structure.

Metamaterial inspired patch antenna miniaturization technique

Abstract: Over the past decade, the need for small, compact and low cost antennas has increased tremendously for applications such as wireless communications and radar. Microstrip patch antennas, though popular for these applications, are difficult to miniaturize, since their resonant frequency is determined by the dominant (TMZ 110 ) mode of the patch cavity (the region immediately beneath the patch). Nevertheless, numerous miniaturization techniques using shorting posts, active loading or high permittivity dielectrics [1] have been conceived to lower the resonant frequency of patch antennas without increasing their size. Unfortunately, as the demand for ever smaller patch antennas increases, these techniques fail to produce the required size reductions.

Compact Metamaterial-Based UHF RFID Antennas: Deformed Omega and Split-Ring Resonator Structures

Abstract: Over the past decade, researchers have shown significant advances in the area of radio frequency identification (RFID) and metamaterials. RFID is being applied to a wide spectrum of industries and metamaterial-based antennas are beginning to perform just as well as existing larger printed antennas. This paper presents two novel metamaterial-based antennas for passive ultra-high frequency (UHF) RFID tags. It is shown that by implementing omega-like elements and split-ring resonators into the design of an antenna for an UHF RFID tag, the overall size of the antenna can be significantly reduced to dimensions of less than 0.15λ0, while preserving the performance of the antenna.

Design of a low-loss low-noise tapered slot phased array feed for reflector antennas

Abstract: Upgrading the Multi-Frequency-Front-Ends of the Westerbork Synthesis Radio Telescope (WSRT) by multiple-beam phased array feeds will improve its survey speed by a factor 20. The present paper describes two design steps of the dual-polarized tapered slot antenna (TSA) array required for this upgrade. Redesign of the TSA element, integration of the Low Noise Amplifier on the feed line substrate and a more rigid connection between the elements improved the low-noise performance, stability and reproducibility of the array. Although, the described array is aimed to be used as a phased array feed, the approach is also applicable in directly radiating beam-steering antenna arrays.

Concurrent dual-band six-loop-antenna system with wide 3-dB beamwidth radiation for MIMO access points

Abstract: A high-gain, wide-beamwidth, six-loop-antenna MIMO system suited for wireless access points in the concurrent WLAN 2.4 and 5 GHz bands is presented.The antenna system mainly comprises an antenna ground plane and single-band loop antennas, among which the three antennas are designated for 2.4 and 5 GHz operation, respectively. The antennas are set in a sequential, rotating arrangement on the ground plane with an equal inclination angle of 60° to form a symmetrical structure, and the 2.4 and 5 GHz loops are facing each other one by one. The experimental results show that good port isolation can be obtained between antenna ports. High-gain, directional radiation patterns with wide 3-dB beamwidth in elevation planes are also observed. Details of a design prototype are described and discussed in the article. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1253–1258, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25208

Ring resonator-based broadband photonic beam former for phased array antennas

Abstract: This thesis presents the principles and a demonstration of optical ring resonator (ORR)-based broadband photonic beam former for phased array antennas. In Chapter 1 an introduction of RF photonics is given. The SMART and BPB projects are summarized, which are aimed for the development of ORR-based broadband photonic beam former for phased array antennas. In the SMART project the antenna is used for the aeronautic communication of Ku-band signals; in the BPB project the antenna is part of a radio telescope which is used for astronomical research.

Challenges with optically transparent patch antennas for small satellites

Abstract: Satellites have always played an important role in space. Their contributions for space research, extended global communications and surveillance have been instrumental for the advancement of the information age. As part of the effort to create this outer space network, small satellites that in average weigh less than 5 Kg are becoming important players in space communications. Limitations of surface area on small satellites leave barely enough room for solar cells, which are necessary to power the internal systems of the satellite. This repeatedly impedes the placement of external elements such as antennas. Without the required surface area for topical microstrip patches, complex and failure prone antennas, such as deployable parabolic reflectors, are often used. This adds substantially to cost and labor hours as well as the potential for failure. Transparent and conductive materials such as ITO (Indium Tin Oxide) have been used in the developed of topical patch antennas [1], [2] that could potentially be mounted on top of solar cells. ITO has a high optical transparency (90%–80%) at very thin depositions (100nm-1.2um) while maintaining a considerably high conductivity of 281319 S/m. However, at very thin depositions efficiency of patch antennas is severely handicapped by skin and ground effects. This paper presents a revised expression for surface resistivity that better accounts for these effects at both low frequencies (100MHz) and high frequencies (10 GHz). Furthermore, this paper addresses the challenges involved with patch antennas made from transparent materials for integration with solar cells.

Low profile array with reduced Radar Cross Section

Abstract: The use of a band-stop Frequency Selective Surface for reducing the Radar Cross Section of an antenna array is described. For the first time such approach is employed for the case of an array of patch antennas with emphasis on the effects on the Radar Cross Section reduction and on the radiation performance of the new structure.

Dual-polarization performance of the phase-tilt antenna array in a casa dense network radar

Abstract: In this paper the evaluation of dual-polarized scanning performance of a large planar array antenna for a solid state radar for weather is discussed. The antenna array is designed to operate at 9.36 GHz ±50 MHz, and the transmission and reception mode is configured to work alternatively. The antenna array architecture based on a series-fed array configuration of Dual-Polarized Aperture Coupled Patch Antennas (DP-ACPA) was designed and implemented to achieve the required radar polarimetric performance at low cost. Measured patterns of the array in the elevation and azimuth plane are used to evaluate the two principal polarimetric radar parameters (Z dr and LDR) over the scanning range in azimuth plane. It is shown that the biases in the differential reflectivity due the cross-polarization of this antenna configuration are negligible in comparison with the biases produced for the mismatch antenna patterns (H and V).

Phased array millimeter wave imaging techniques

Abstract: An apparatus, imager elements, and a method for detecting a radio frequency image using phased array techniques. An example apparatus includes an array of radio frequency antennas fabricated on one or more packaged integrated circuits. The apparatus also includes a controller configured to selectively phase shift radio frequency signals from the antennas such that the at least a portion of the radio frequency image is focused.

Design and optimisation of Yagi-Uda antenna arrays

Abstract: The geometry optimisation of linear and two-dimensional (2D) Yagi-Uda antenna arrays is presented. The objective from the optimisation is to increase the directivity and/or minimise the sidelobe level. The optimisation parameters are the lengths and/or the separations between the array elements for the linear array, and lengths and element locations for the 2D array. The current distribution over the array elements is found using the method of moments that takes into consideration mutual coupling between array elements. From the current distribution and the array geometry, the radiated electric field is computed, from which the directivity and other array parameters are calculated. The particle swarm optimisation (PSO) method is used in the optimisation process. Various numerical examples are presented and discussed, and the results are compared with other optimisation methods whenever possible.

UHF near-field RFID antennas

Abstract: Near-field radio frequency identification (RFID) technology has been traditionally used at low frequency (LF) and high frequency (HF) bands; now developing this technology at ultra high frequency (UHF) band is of increasingly interest. Designing a UHF near-field RFID reader antenna is one of the most challenging tasks. Traditional loop antennas cannot operate properly at the UHF band when the antennas tend electrically large so that they are unable to generate strong and uniform magnetic field in an adequate interrogation zone. A number of techniques have been presented to design UHF near-field RFID reader antennas, which enables the electrically large loop-type antenna generating desired magnetic field distribution. In this paper, the challenges of the UHF near-field antenna design are addressed. The state-of-art UHF near-field antenna techniques are reviewed and discussed.

Dual polarization receiving antenna array for recording of ultra-wideband pulses

Abstract: The results of investigation of a 4 × 4 ultra-wideband dual polarization receiving antenna array designed for investiagtion of the polarization structure of nanosecond and subnanosecond electromagnetic pulses are presented. The elements of this antenna array are the crossed dipoles whose arms are loaded with single-stage FET amplifiers. The results of measurements of the patterns, the effective length, and the wave-forms of the recorded pulses are presented for different values of the array interelement spacing and the directions of arrival of radiation.

Planar antenna arrays at 60 GHz realized on a new thermoplastic polymer substrate

Abstract: Electromagnetic waves are severely attenuated at the 60 GHz band and therefore high gain antennas are mandatory to assure medium as well as long distance communication. Efficient antennas like dish and waveguide antennas might be used for outdoor applications, however, their big size and/or high cost is an obstacle for cost-efficient and low profile indoor systems. The investigation of highly directional microstrip patch antennas at the mm-wave is done employing the new low loss thermoplastic polymer substrate material ER182. The antennas are designed and solved using a frequency domain solver. Then, the results are numerically verified by re-solving the designed antennas with a time domain solver that yields a good agreement. In addition, a prototype set of 7 different antennas, starting with a single patch antenna and up to a 32×32 planar antenna array, are fabricated and measured. The measurements show a gain of up to 23 dBi, an impedance bandwidth that exceeds 3 GHz, and a realizable HPBW of 2°. The use of ER182 substrate material enhances the antenna efficiency, compared to other well known materials, however the realization of high gain antennas is still very limited compared to waveguide antennas.

Millimeter-wave plastic waveguide phased array antenna

Abstract: Low cost and high performance millimeter-wave phased array antennas have been demanded in recent years due to increasing millimeter-wave applications in highspeed mobile communications, broadband wireless LAN/PAN (WLAN/WPAN), automotive collision avoidance radars, and so on. Several types of millimeter-wave antennas and components have been proposed for these systems. For example, plastic waveguide structures, which are composed of hollow liquid crystal polymer (LCP) and plated copper [1], [2], have been reported in order to reduce the cost for mass-production scheme. However, the phased array antennas are difficult to form their complex configurations and difficult to obtain low-loss characteristics as well. This paper presents millimeter-wave waveguide-type phased array antennas using low-loss engineering plastics not only to reduce cost but also to obtain high performances with complex configurations. That is a Cyclo-Olefin Polymer (COP) waveguide horn array antenna which is fabricated by injection molding process [3].

Compact planar MIMO antenna array with polarisation diversity on single layer

Abstract: A novel compact and planar MIMO antenna array with polarisation diversity is proposed on a single layer. The proposed array is composed of two orthogonal polarised elements which act as electric and magnetic loop antennas. A high isolation of 20 dB between the two antennas is achieved at 2.3 GHz. The overall size of the array is 38 × 28 mm (i.e. 0.291 × 0.214 λ 0 ). The calculated envelope correlation coefficient is 0.00035.

High-resolution radar map for multi-function phased array radar

Abstract: A method of operating a multi-function phased array radar system having an antenna array populated with dual-pol antenna elements is described. The method includes selectively controlling individual dipoles of each dual-pol antenna element in order to operate the array in either a polarimetric mode with improved cross-pol isolation, or in a multi-mission mode, wherein a plurality of singularly-polarized signals are produced.

Direction Assignment in Wireless Networks

Abstract: In this paper we consider a wireless network, where each transceiver is equipped with a directional antenna, and study two direction assignment problems, determined by the type of antennas employed. Given a set S of transceivers with directional antennas, located in the plane. We investigate two types of directional antennas | quadrant antennas and half-strip antennas, and show how to assign a direction to each antenna, such that the resulting communication graph is connected.

Time-domain design of UWB Vivaldi antenna array using multi-objective particle swarm optimization

Abstract: An ultrawideband (UWB) antenna array was designed to optimize the beamwidth of the time-domain radiation pattern as well as the side lobe level. Multi-objective particle swarm optimization (MOPSO) was applied in dealing with these two conflicting objectives and finding the optimum trade-offs (Pareto front). Mutual coupling was not considered in the array design. However, the multiple solutions that resulted from MOPSO enable the designer to consider the minimum inter-element spacing as an additional constraint for selecting the appropriate array configuration with negligible mutual coupling effect. Each element of the array was an antipodal Vivaldi antenna. The optimization template was applied for three different timedomain pattern descriptors. In comparison to the arrays with the same number of elements reported in the literature, the Pareto fronts obtained in this study provide lower beamwidth and side lobe level. A 4-element sample from resultant Pareto fronts was simulated by using CST microwave studio software. This array shows a 13.7–17.2 dBi gain over the whole frequency band from 3–11 GHz and 7.2 ° beamwidth and −12 dB side lobe level for the energy pattern.