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Microwave Landing System[1] (MLS) is a new standard system endorsed by the International Civil Aviation Organization (ICAO) to replace Instrument Landing Systems (ILS) now in general use. MLS operates at C-Band which permits ranges up to 30 nautical miles to be reliably achieved with modest transmitting powers. With MLS's, ground transmitters provide signals that can be decoded in an aircraft to determine...
A broadband monopole is investigated. The bandwidth enhancement is achieved by loading a monopole with a dielectric resonator antenna (DRA) operating in a TM01δ mode to maintain a desirable omnidirectional radiation pattern. Preliminary results validate the design concept.
A unit cell comprised of a circular aperture is modelled centered in the ground plane beneath a microstrip patch. A phase change of 82–86° is obtained at the patch resonant frequency in the far-field for a cell radius of 0.4L, where L is the resonant length of the patch. A stacked patch structure is investigated to maintain an adequate match at the resonant frequency of the unloaded patch. A phase...
A linear tapered slot antenna (LTSA) is investigated as a novel feed mechanism for holographic antennas. This new slotline feed is low profile and compact in comparison to traditional holographic antenna feeds such as open waveguides and horns. Measured results indicate that the LTSA is an efficient and viable feed for holographic antennas.
In this paper, a method for obtaining the generalized scattering matrix coefficients of both the propagating and evanescent modes of waveguide discontinuities is presented. The method is based on the modal expansion of field distributions obtained from Transmission Line Matrix (TLM) simulations and use of the orthogonality principle to quantify the presence of specific modes. Using this approach,...
A conventional transmit system design comprises a high gain antenna followed by a solid state power amplifier (SSPA). However, the SSPA used within a transmit system have in general multiple devices to provide the high output power and suffers from the combining losses within the unit. To reduce these losses, low to medium power amplifiers are integrated within an array architecture. Spatial power...
In this paper, the effect of amplitude and phase errors as well as amplifiers and phase shifters failures on a phased array performance is investigated. It is found that random phase errors and phase shifters failures are dominant factors, they influence the peak sidelobe level, pointing angle accuracy, directive power and the half power beamwidth.
A reflectarray antenna composed of double cross loop elements of varying arm length printed on a conductor-backed substrate is introduced. Two different realizations are presented: in the first design, the lengths of both constituent arms of the cell elements are varied whereas the length of only one of the two arms is varied in the second design. Prototype reflectarrays were fabricated and measured...
An investigation of rectangular Dielectric Resonator Antennas (DRA) for use in mobile communications applications was undertaken at L-Band frequencies (1–2 GHz). Techniques were developed to improve the performance of probe fed DRA. The resonant frequency was reduced by 40% by grounding the edge of the DRA opposite the feed probe. Inserting a low dielectric constant material between the DRA and the...
A design procedure and experimental results are presented for single and dual-band, multilayer transmitarray antennas, operating at Ka-Tx/Rx bands (Tx=30 GHz, Rx=20 GHz). The performances of these transmitarray antennas are compared to reflectarray antennas of the same size. Efficiency figures of 50% and 35% were observed for single-band and dual-band transmitarrays, respectively, which were close...
A circularly polarized dielectric resonator antenna has been developed recently for K-Band applications [1]. A microstrip aperture-coupled dielectric resonator element in the shape of a cross was designed as a feed element for a cylindrical cavity antenna. The analysis was performed using a Finite Difference Time Domain (FD-TD) method [2]. As part of the continuing development of this antenna, it...
Interest in the use of microstrip patches for array antennas has prompted investigations into numerous feed mechanisms. One of the most interesting, which offers considerable advantages over the others, is aperture coupling. In the paper that follows, the coupling of a feedline to a rectangular patch, through an aperture in the ground plane separating them, is described. Modal field expansion is used...
An analysis of slot-coupled double layer microstrip lines is presented. A modal field expansion method and the Poynting theorem are applied to derive the input impedance as seen by the feed line at the slot. By comparing the theoretical results with measured values, the accuracy of the method is verified.
This paper investigates a novel multi-segment dielectric resonator antenna (DRA). The antenna consists of a thin segments of different permittivity material bonded to the underside of a rectangular dielectric resonator segment. The multi-segment DRA element is excited by a microstrip line. The permittivity and thickness of the segments are used to concentrate the fields of the micro-scrip line and...
The rapid growth of spectral utilization has necessitated the progress toward higher frequency bands to resolve the spectral crowding problem. However, before the successful transition to higher frequency bands can be realized, critical components and appropriate tools such as propagation modelling need to be developed. In the millimeter-wave band, many of these technologies have progressed rapidly...
Transitions between microstrip and NRD-guide are required by integrating NRD circuits to planar circuits and NRD circuit measurement. The transition proposed in [1] offers a promising solution in view of practical applications, but it has to be accurately modeled and optimized to achieve its best possible performance. In this paper, the transmission line matrix (TLM) method has been successfully used...
An active integrated antenna may be defined as a radiating element on which the current distribution along the structure may be altered in a controlled manner. The ability to control the current distribution along its structure is the unique feature of this class of antennas and gives it its primary advantage. With this ability, radiation characteristics such as pattern shape, axial ratio, and gain...
Recently, dielectric resonator antennas (DA) have been proposed as alternative radiators to the popular microstrip patch [1]-[3]. They have been demonstrated to possess characteristics similar to those of microstrip patches, i.e. low profile and compatibility with planar integration technologies, both desirable properties for future active phased arrays. However, they also have advantages over microstrip...
As telecommunications and radar systems are increasingly being designed to operate at higher and higher frequencies in the millimetre wave band, antenna designers have looked arrays, with feed networks based in microwave integrated circuit (MIC) technology, to meet the antenna requirements of these systems. Most of the research and design into arrays for millimetre wave applications has focused on...
An experimental investigation of a novel ferrite resonator antenna has been performed. A ferrite antenna with rectangular cross-section was subjected to a static magnetic bias field, applied in two orthogonal directions, in a plane parallel to the antenna height. The effects on the resonant frequency, radiation efficiency and farfield patterns of the antenna were investigated. A maximum frequency...
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