Showing papers on "Reflective array antenna published in 2009"

An investigation of a frequency diverse array

Abstract: This thesis presents a novel concept for focusing an antenna beam pattern as a function of range, time, and angle. In conventional phased arrays, beam steering is achieved by applying a linear phase progression across the aperture. This thesis shows that by applying an additional linear frequency shift across the elements, a new term is generated which results in a scan angle that varies with range in the far-field. Moreover, the antenna pattern is shown to scan in range and angle as a function of time. These properties result in more flexible beam scan options for phased array antennas than traditional phase shifter implementations. The thesis subsequently goes on to investigate this phenomenon via full scale experimentation, and explores a number of aspects of applying frequency diversity spatially across array antennas. This new form of frequency diverse array may have applications to multipath mitigation, where a radio signal takes two or more routes between the transmitter and receiver due to scattering from natural and man-made objects. Since the interfering signals arrive from more than one direction, the range-dependent and auto-scanning properties of the frequency diverse array beam may be useful to isolate and suppress the interference. The frequency diverse array may also have applications to wideband array steering, in lieu of true time delay solutions which are often used to compensate for linear phase progression with frequency across an array, and to sonar, where the speed of propagation results in large percentage bandwidth, creating similar wideband array effects. The frequency diverse array is also a stepping stone to more sophisticated joint antenna and waveform design for the creation of new radar modes, such as simultaneous multi-mode operation, for example, enabling joint synthetic aperture radar and ground moving target indication.

Focused Microstrip Array Antenna Using a Dolph-Chebyshev Near-Field Design

Abstract: A new concept in designing large array antennas to focus the microwave power in the radiation near-field region is presented A small focused array antenna using microstrip patch elements to achieve the desired sidelobes levels in the Fresnel region based on Dolph-Chebyshev design is implemented This array is built to verify the concept, and then the measured and computed near fields are compared to verify the accuracy of the design Larger arrays are designed by using the knowledge of the mutual admittances between the elements of smaller arrays Several computed examples are presented in order to show some properties of focusing arrays It is shown that the maximum intensity of the electric field along the axial direction is displaced from the focal point towards the antenna aperture This displacement decreases as the aperture size increases

Conformal array design with transformation electromagnetics

Abstract: We apply the theory of transformation electromagnetics to source arrays and show that a complex conformal antenna array can be made to behave like a geometrically different array when surrounded with a properly designed transformation electromagnetics medium Numerical simulations are presented to show how a nonuniform circular array can be made to radiate and receive as a uniformly spaced linear array In this way, transformation electromagnetics provides a method by which all of the advantages of simple arrays in array processing, such as beamforming, can be retained in an array whose elements are constrained to a complex geometry

Low Cost Reconfigurable Landstorfer Planar Antenna Array

Abstract: In this paper, we introduce a practical design for a Landstorfer planar antenna that can be implemented as a compact and low cost reconfigurable planar antenna array. The array, we propose, can have 360-degree coverage in azimuth and allows a wide variety of directive beams to be electronically selected while maintaining a simple structure, ease of manufacture and low cost with high efficiency. One of the possible applications for this array is in WLAN systems where high gain and low cost adaptable antennas promise increases in capacity and coverage. The array design utilizes key innovations in the design of Landstorfer antennas and feed/switching network. The Landstorfer antenna exhibits a high gain with 9.5 dBi and low mutual coupling between elements. A proposed reflector for the Landstorfer antenna is implemented and it allows the antenna array to be fabricated on a 2-layer PCB board. We also present a low cost feed/switching network which allows flexible control of the antenna patterns. The design makes use of PIN diodes as switching elements and a resonant inductor to improve the isolation of the PIN diodes. By integrating the antenna elements, feed/switching network and array configuration, a low cost reconfigurable Landstorfer planar array can be formed.

Highly Efficient Leaky-Wave Antenna Array Using a Power-Recycling Series Feeding Network

Abstract: A highly efficient leaky-wave antenna (LWA) array using a power-recycling series feeding network is proposed. The input power to the antenna array is efficiently recycled within the array elements and completely leaked out before reaching the terminations. Consequently, the array achieves high radiation efficiency and gain while maintaining a reasonable length in the direction of wave propagation. Simulated and measured results validate the proposed concept.

Inkjet printed paper based quadrate bowtie antennas for UHF RFID tags

Abstract: Paper substrate is one of the paramount nominees for Radio Frequency Identification (RFID) tags, for the reason that it is one of the widely and the cheapest available substrates. In this paper, for the first time quadrate bowtie antennas with round corners [1] are realized and analyzed on paper substrate for UHF RFID tags. These inkjet printed antennas exhibit high performance which give freedom for their applications. Their area is smaller than the general triangle bowtie antenna and have advantages of smaller area, better return loss in high frequency and higher gain in normal direction of antenna plane compared with general triangular bowtie antenna.

Compact Ultrawideband UHF Array Antenna for Through-Wall Radar Applications

Abstract: A compact ultrawideband (UWB) array antenna has been developed for through-wall radar surveillance and tested using a noise radar. The operating frequency is in the UHF range, and the design is based on the concept of future wearable array antennas. The printed elliptical patch antenna element features an available bandwidth of almost 100% (325-1000 MHz) and a compact size of 10.2 × 10.2 × 0.3 cm3 (0.14?L × 0.14?L × 0.004?L). It has useful merits, including vertical polarization and omnidirectional coverage in azimuth plane. A portable eight-element antenna array, with a maximum dimension less than 1.8 m, was subsequently developed for a through-wall noise radar. This small array has been tested with uniform amplitude distributions for the preliminary beamforming evaluation.

Design and probe based measurement of 77 GHz antennas for antenna in package applications

Abstract: The development and the measurement of two planar antenna structures is presented. These antennas are prospective candidates for the integration into compact millimeter-wave packages for 77 GHz automotive Radar applications. The antennas were manufactured using only one metal layer on top of a 127 µm Alumina substrate. Gain, radiation pattern and Return Loss of the antennas are characterised using a novel probe based measurement setup.

Study on the performance deterioration of flexible UWB antennas

Abstract: A flexible transparent film uwb antenna for curved surfaces has been designed and developed for wireless communications. The antenna has demonstrated good performance over the entire UWB bandwidth. It can be mounted on any conformal shape by virtue of the film properties of both the antenna as well as the substrate. The radiator and ground are both designed using AgHT-8 while the substrate is of a polymer. The antenna is shown to be able to maintain its performance below the 10dB level throughout the entire UWB bandwidth of 7.5GHz i.e from 3.1 GHz to 10.6 GHz as it is flexed through various radius of curvature thus providing an insight into how to overcome performance deterioration in wearable antennas.

UWB Vivaldi antenna for impulse radio beamforming

Abstract: In this paper, two different types of Vivaldi antenna are designed and tested suitable for electromagnetic beamforming. The first is an antipodal Vivaldi antenna, while the other is a tapered slot Vivaldi antenna. They are both ultra wideband antennas for the 1GHz to 5GHz frequency band. They have low impulse distortion and the voltage standing wave ratio (VSWR) less than 2 throughout the entire bandwidth. The antennas are used for impulse radio beamforming.

A Beam-Steering and -Switching Antenna Array Using a Coupled Phase-Locked Loop Array

Abstract: We present the analysis and experimental results of a beam-steering and -switching antenna array using coupled oscillators and phase-locked loops. With the use of a type-II coupled phase-locked loop array and an external reference signal, the antenna array can steer its beam by a single control voltage, reduce the beam-pointing error arising from the phase errors of the oscillator array, and hold its output frequency stably at the reference signal frequency in operation. Using a double-pole double-throw switch and a difference amplifier at the center element of the antenna array, one can switch the array radiation pattern between the sum pattern and the difference pattern. Moreover, the beam-scanning range is extended to plusmn 90deg by properly using frequency prescalers in the phase-locked loops. The radiation characteristics of a three-element antenna array are measured to verify the array performance.

Millimeter-wave waveguide-type array antennas using low-loss engineering plastics

Abstract: This paper presents two types of millimeter-wave waveguide-type array antennas using low-loss engineering plastics. The first one is a Cyclo-Olefin Polymer (COP) waveguide horn array antenna which is fabricated by the injection molding process. The other is a post-wall slotted waveguide array antenna with an offset directional beam using a post-wall rectangular waveguide inside a Grafted Olefin-Styrene resin printed circuit board. The injection molded waveguide and the post-wall waveguide realize low loss characteristics of 0.1 – 0.3 dB/cm at 40GHz and 60GHz bands, respectively. The fabricated array antennas have good performances. Also, measured performances agree with the calculated ones. The authors clarify that the mass production and cost reduction of millimetre-wave antennas are capable by using these techniques.

Development of microstrip array antenna for wide band and multiband applications

Abstract: The paper presents the design and development of an X-band linearly polarized microstrip array antenna. The array elements are fed by corporate feed network, which improves the impedance bandwidth of the two element rectangular microstrip array antenna (2RMSAA) by 15.38%. By increasing the array elements from two to four and eight, multiband operation can be achieved with improved impedance bandwidth. These multiband array antennas may provide an alternative to large bandwidth planar antennas in applications where large bandwidth is needed for operating at two separate transmitreceiver frequencies. When the two operating frequencies are far apart, a multiband antenna can be used to avoid the use of separate antennas. Experimental results for the array antennas in term of return loss, radiation pattern, -3dB beam width, and gain are presented.

Wideband multifunction airborne antennas

Abstract: Increase of functions and improvement of performance required on board aircrafts, associated to the limited amount of available areas to implement the equipments drive an approach leading to grouping of functions operated in various frequency bands and to reduction of thickness of the antennas Technical and technology research is being conducted on wideband and multi-band radiating structures, making in particular use of metamaterials and FSS structures, and the overall architecture has to deal with the various requirements

Optical and Microwave Beamforming for Phased Array Antennas

Abstract: Phased array antenna has been used for a variety of military and civil applications, over the past five decades. Being structurally conformal and flexible, phased array antenna is highly suitable for mobile applications. Besides, it can form the agile or shaped beams required for interference cancellation or multifunction systems. Moreover, the spatial power combination property increases the effective radiated power of a transmitter phased array system. Similarly, in a receiver phased array, beamforming increases the signal to noise ratio by coherent integration of the desired signals. Despite its impressive potentials and properties, phased array antenna has not become a commercial product yet. Cost and complexity of phased array antenna are beyond the scales of consumer electronics devices. Furthermore, calibration is an essential requirement of such a complex system, which is a fairly time-consuming process and requires skilled man power. Moreover, the narrow bandwidth of microwave components degrades the broadband performance of phased array system. Finally, the majority of the beamforming algorithms developed so far have preconditions, which make them unsuitable for a low-cost system. The objective of this thesis is to provide a novel cost-effective solution to minimize the system complexity of the future intelligent antenna systems, without sacrificing the performance. This research demonstrates that a powerful, robust beamforming algorithm, integrated in an efficient single-receiver architecture, constitutes the essence of a low-cost phased array antenna. Thus, a novel beamforming technique, called Zero-knowledge algorithm is developed. It is investigated, both theoretically and experimentally, that the proposed algorithm can compensate for the hardware errors and imperfections of the low-cost components of the system. Zero-knowledge beamforming algorithm possesses significant properties. Neither a priori knowledge of the incoming signal direction, nor the exact characteristics of the phase control network are required in this method. Proper adjustment of the parameters, makes this algorithm appropriate for mobile systems, particularly those installed on vehicles. The algorithm alleviates the drawbacks of analog phase shifters, such as imbalanced insertion loss and fabrication tolerances. Furthermore, this algorithm can serve as the core of a direction-of-arrival estimation technique, which senses the minor deflections of the array heading. For broadband applications optical delay lines must be used in the phase control network of the phased array systems, which are costly. Nevertheless, employing

An Efficient Pattern Synthesis Method for Cylindrical Phased Array Antennas

Abstract: An efficient approach for calculating the far field pattern of conformal phased array antennas mounted on cylindrical-shaped platforms is proposed. The array structure is taken into account by using an active element pattern technique, and the array is analyzed by using an element-by-element approach. The effects of all mutual couplings in the array environments are considered rigorously, and the efficiency of the proposed method is validated by using the commercial full-wave simulation software HFSS. Finally, a low side-lobe cylindrical phased array is designed for engineering by optimizing phases and amplitudes of port excitations.

Combined transmit/receive single-post antenna for HF/VHF radar

Abstract: An antenna configuration is described for high frequency (HF) or very high frequency (VHF) radars contained in a single vertical post. The radar may include a vertical dipole or monopole transmitting antenna collocated with a three-element receive antenna. The three antennas including two crossed loops and a vertical element are used in a direction-finding (DF) mode. Isolation between the three antennas produces high quality patterns useful for determining target bearings in DF mode. The single vertical post is sufficiently rigid mechanically that it may be installed along a coast without guy wires.

Broadband single-layer triple-resonance microstrip reflectarray antennas

Abstract: This paper presents single-layer microstrip reflec-tarray antennas based on triple-resonance behavior and also discusses their broadband characteristics. The reflection phase properties can be evaluated by using infinite arrays of a rectangular cell consisting of three elements with different dimensions. Appropriate three elements for obtaining arbitrary phase value are determined by taking account of both range of the phase shift at the centre frequency and its slope for the frequency characteristics. We design various reflectarrays with a main beam in a specified direction and also evaluate the frequency characteristics. Finally, the effectiveness of the designed antenna is verified by calculated and measured results around 10–19 GHz.

Three-dimensional phased array antenna analysis and simulation

Abstract: The beam width of planar phased array antenna becomes large as increasing of the scanning angle, so that the scanning range is limited. Conformal phased array antennas might be applied to improve the scanning range. However, the element distribution of a conformal phased array is not regularization, so the analysis is very complicate. In this article, a three-dimensional (3D) array antenna is investigated and implemented on Matlab. 3D array antenna can form different types of arrays to scan any space through choosing different elements. This paper introduces a general direction function of 3D array antenna and simulations of three typical types of arrays formed: diagonal planar array, trapezoidal array and curved surface array. It also investigates the differences of the beam patterns.

Antenna performance for ultra-wideband microwave imaging

Abstract: Numerous antenna designs have been proposed for microwave breast imaging utilizing an ultra-wideband frequency range. The antennas are typically compact, operate in an immersion medium, and have a band covering at least 2–10 GHz. We have developed 3 antennas for our UWB microwave breast imaging system. In this contribution, we compare the performance of the antennas in order to gain insight into the relationship between antenna performance metrics and image quality.

Integration of conformal GPS and VHF/UHF communication antennas for small UAV applications

Abstract: The integration of GPS and VHF/UHF antennas occupying the same physical volume conformal to the tail of a small UAV is presented in this paper. Traditionally each antenna requires its own volume, thus limiting the number of antennas, reducing the UAV functionality. The GPS antenna covers both the L1 and L2 bands while the VHF/UHF antenna can operate from 30 MHz up to 300 MHz.

Design of a KA-band wide scanning phased array antenna

Abstract: The general issue of this paper deals with the design of a phased array antenna for high data rate SATCOM on UAV (Unmanned Aerial Vehicle) in Ka band. This paper presents: 1) a comparative study of possible antenna element candidates for a 30 GHz circularly polarized and wide angle scan phased array. 2) a new low loss analog phase shifter concept. This will lead to the conception of a phased array antenna and also of phase shifters.

Characterisation of ultra wideband wearable antennas and body-centric wireless-networks in indoor environment

Abstract: The effect of human body and indoor environment in the ultra wideband (UWB) radio propagation channel is presented. Measurements were performed in the frequency domain, and the effect of two different antenna types on the radio channel is analyzed. Statistical path loss parameters and time domain channel characteristics [pulse fidelity] are extracted from measurement data. The analysis of the pulse fidelity shows good performance of both antennas proposed in preserving the shape of the received pulse. This demonstrates suitability of these two antennas for body-centric wireless networks when deployed in indoor applications, with the tapered slot antenna (TSA) gaining advantage on the planar inverted cone antenna (PICA) from spectral performance and significant size reduction that makes it an attractive and convenient option for the targeted system.

A Log Periodic Series-Fed Antennas Array Design Using A Simple Transmission Line Model

Abstract: In this paper, a transmission line model is used to design a series-fed log periodic antennas arrays over a band of frequencies for satellite communications. The transmission line model is simple, precise and allowing taking into account the whole geometrical, electrical and technological characteristics of the antennas arrays. To validate this last, the obtained simulation results are compared with those obtained by the moment’s method (MoM). Using this transmission line approach the resonant frequency, input impedance, return loss can be determined simultaneously. Agreements between transmission line model data and the moment’s methods results were achieved.

Marine multiband antenna

Abstract: A marine multiband antenna array includes a nearly virtual bowtie UHF antenna and a connected VHF/FM antenna that together function as an AM antenna. A diplexer separates the AM/FM radio signals from the UHF/VHF television signals.

Novel Method for Characterizing Filtering Antennas

Abstract: Ultra-wideband systems show promise in high-data-rate radio communications. However, these systems interfere with other communication protocols, such as WLAN. To solve this problem, current work proposes the insertion of thin half-wavelength slots in the antenna's structure, thus creating filtering antennas. Many criteria were used to characterize the filtering of these antennas, such as the measurement of the VSWR, the return loss, and the maximum gain of the antenna as a function of frequency. In this paper, we show by studying the three-dimensional gain pattern of these antennas that their filtering is not just dependent on the frequency, but that it also depends on the radiation direction, due to the radiation of the slots. We then propose efficiency measurement as the best way to quantify the filtering of these omnidirectional antennas, independently of the radiation direction. Two filtering antennas were characterized using a modified wideband Wheeler-cap efficiency-measurement method.

Conformal wide bandwidth antennas and arrays

Abstract: Various widebandwidth antennas and challenges using these antennas for conformal phase arrays are presented. Problems that arise depending on the physical separation of the antennas and corresponding separations in terms of wavelength are discussed. For conformal placement of an antennas either as an individual antenna or as in an array configuration on any arbitrary surface may require very thin antenna structures. They should be processed preferably on flexible substrates so that they will conform to the surfaces without changing the surface geometry. Archimedean slotted spiral antennas that satisfy these requirements will be used to demonstrate problems associated with UWB phased arrays.

A compact 4-element dual-band GPS array

Abstract: A compact 3.5″ 4-element dual-band GPS array was designed for adaptive nulling applications. An important feature of this design is antenna miniaturization via slots (inductive) loading. This design concept can, of course, be applied to other narrow-band antennas. Simulated results were given exhibiting good performances when the antenna is functioning in isolation and in-situ of the array.

Antenna Composition and Technology for Cognitive Wireless Communications

Abstract: Antenna composition that can be applied for cognitive wireless communications is classified into switching antennas, wideband antennas and tunable antennas in this article. Some techniques to realize those multi-band antennas are proposed and they are numerically or experimentally examined.