Query: parasitic patch beam steering

title: A Beam Steering Reconfigurable Antenna for WLAN Applications
abstract: A multifunctional reconfigurable antenna (MRA) capable of operating in nine modes corresponding to nine steerable beam directions in the semisphere space 30deg,0deg, 30deg} ph {0deg, 45deg, 90deg, 135deg} is presented. The MRA consists of an aperture coupled driven patch antenna with a parasitic layer placed above it. The surface of the parasitic layer has a grid of 3 x 3 electrically small square shaped metallic pixels. The adjacent pixels are connected by PIN diode switches with ON/OFF status to change the geometry of the parasitic surface, which in turn changes the current distribution on the antenna, thus provides reconfigurability in beam steering direction. The MRA operates in the IEEE 802.11 frequency band (2.4 2.5 GHz) in each mode of operation. The antenna has been fabricated and measured. The measured and simulated impedance and radiation pattern results agree well indicating an average of 6.5 dB realized gain in all modes of operation. System level experimental performance evaluations have also been performed, where an MRA equipped WLAN platform was tested and characterized in typical indoor environments. The results confirm that the MRA equipped WLAN systems could achieve an average of 6 dB Signal to Noise Ratio (SNR) gain compared to legacy omni directional antenna equipped systems with minimal training overhead.

title: Survey of Beam Steering Techniques Available for Millimeter Wave Applications
abstract: Pattern reconfigurable antennas (beam steerable antennas) are essential for various applications in electronic engineering such as telecommunication and radar. They mitigate interference by channelling the antenna's radiation to the direction of interest. This ability is vital for millimetre wave frequency applications such as small cell backhaul links where high path loss, attenuation from obstacles, and misalignment due to wind sway and accidents are prevalent. Several techniques have been used to implement beam steering over the years, most of which achieves steering at the expense of antenna performance. In this article, we surveyed the various techniques used in achieving beam steering and analyse each based on some figures of merit with the aim of identifying areas of improvements for each beam steering technique.

title: Beam steerable patch antenna array using parasitic coupling and reactive loading
abstract: A parasitically coupled and reactively loaded patch antenna array is demonstrated to achieve beam steering in an analog manner. The strong parasitic coupling between closely spaced patch antennas is used to form a phased array with a single driven element. The phase shift between the array elements is adjustable by changing the reactive loading on the parasitic patch antenna. A prototype of this antenna array is demonstrated at 2.3 GHz.

title: Electronic beam steering in wire and patch antenna systems using switched parasitic elements
abstract: We explore the application of two alternative methods of electronically controlling the radiation pattern from an antenna array which has a single feed line. Type (a) involves switching one of the parasitic elements to become active. Type (b) requires switching the parasitic elements located in the vicinity of the active element between short circuit (i.e. continuous conduction in the element) and open circuit at a point where the induced current is minimised. Both techniques offer a reduced radiation loss in the feed network and relatively simple control circuitry and tracking software.

title: A Reconfigurable Partially Reflective Surface (PRS) Antenna for Beam Steering
abstract: The design of a novel partially reflective surface (PRS) antenna with the capability of beam steering is presented in this paper. The beam steering is realized by employing a reconfigurable PRS structure to achieve a changeable reflection phase as well as using a phased array as the source to excite the PRS antenna. A prototype antenna including the biasing network is fabricated and measured. It achieves a consistent beam steering from 15deg to 15deg with respect to the broadside direction across an overlapped frequency range from 5.5 to 5.7 GHz with measured realized gains over 12 dBi. Good agreement between the simulated and measured results for the input reflection coefficients and radiation patterns is achieved, which validates the feasibility of the design principle. Compared with other beam steering PRS antennas, the proposed one enables a larger beam steering angle with comparable gains, requires a simpler biasing network, and is more compact.

title: An affordable millimeter wave beam steerable antenna using interleaved planar subarrays
abstract: Design and fabrication aspects of an affordable planar beam steerable antenna array with a simple architecture are considered in this paper. Grouping the elements of a phased array into a number of partially overlapped subarrays and using a single phase shifter for each subarray, generally results in a considerable reduction in array size and manufacturing costs. However, overlapped subarrays require complicated corporate feed networks and array architectures that cannot be easily implemented using planar technologies. In this paper a novel feed network and array architecture for implementing a planar phased array of microstrip antennas is presented that enables the fabrication of low sidelobe, compact, beam steerable millimeter wave arrays and facilitates integration of the RF front end electronics with the antenna structure. This design uses a combination of series and parallel feeding schemes to achieve the desired array coefficients. The proposed approach is used to design a three state switched beam phased array with a scanning width of /spl plusmn/10/spl deg/ This phased array which is composed of 80 microstrip elements, achieves a gain of >20 dB, a sidelobe level of 6.3% for all states of the beam. The antenna efficiency is measured at 33 36% in X band. It is shown that the proposed feeding scheme is insensitive to the mutual coupling among the elements.

title: Experimental study of parasitically steered, fixed beam microstrip patch arrays
abstract: The linearly polarised single feed point Yagi microstrip patch array was previously developed from the concept of the thin wire Yagi Uda array. It is possible to build either vertically polarised or horizontally polarised arrays. Both feed points of an array can be excited with the correct amplitude and phasing to produce circular polarisation. A Yagi microstrip patch array produces a mainlobe away from the zenith, and has the advantage of being planar for applications such as wireless office. The aim of this paper is to investigate the influence of various characteristics of the dielectric substrate upon array performance and to access the effects of reduction of the array size upon its behaviour. The collected experimental data will be useful for comparison to numerical simulations in future work. The linear polarised measurements were undertaken in the anechoic chamber at the University of Manitoba.

title: Separated array antenna with parasitic elements for beam steering control
abstract: A new antenna structure is formed by combining the concept of reconfigurable planar array antenna with the parasitic elements technique to produce the beam steering. The integration of PIN diode switches with antenna enables to steer the antenna beams to the desired direction. This can be done by changing the switch state to either on or off mode. In this work, a number of reflectors have been proposed, namely parasitic elements, and placed between the patches to increase the beam steering angle. With such configuration, the main beam radiated by the array can be tilted due to the effect of mutual coupling between the driven elements and the parasitic elements (reflectors) The unique property of this antenna design is that instead of fabricating all together in the same plane, the antenna's feeding network is separated from the antenna radiating elements (the patches) by an air gap distance. This allows reducing spurious effects from the feed line. The optimization results for the resonant frequencies of the antennas with variable air gap heights were also studied. The simulations results will be compared to measurements at 5.8 GHz. Experimental results are presented to demonstrate the excellent performance of this antenna.

title: A Low Cost 60 GHz Switched Beam Patch Antenna Array With Butler Matrix Network
abstract: In this letter, a low cost 60 GHz switched beam patch antenna array with Butler matrix network is developed and experimentally demonstrated. In order to improve integration with the patch elements, a 4 times 4 planar Butler matrix is implemented in a low dielectric substrate. The four rectangular patches fed by inset microstrip lines are connected to the outputs of the Butler matrix for the 60 GHz operation. Because of the fabrication tolerances, the operating frequency of the fabricated antenna shifts to 62 GHz. The radiation patterns measured at 62 GHz are in good agreement with the theoretical array factors. The antenna developed in this letter provides a cost effective approach to implement an adaptive antenna for 60 GHz wireless communications.

title: Switched parasitic elements for antenna diversity
abstract: Switched parasitic elements provide a useful implementation of antenna pattern diversity. The basic principle is presented with some examples of wire antennas computed using the method of moments. The modeled diversity gain available from selection combining of uncorrelated signals is used to quantify the expected improvement relative to nondiversity antennas. The advantage of the switched parasitic concept is that it is a relatively simple system, which can give the adaptive antenna performance of many branch selection or switched diversity.