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We describe the development of techniques for use in efficient analysis of array antennas containing both highly conducting and inhomogeneous or anisotropic dielectric parts. The techniques have application to extending the Characteristic Basis Function Method (CBFM) to apply to a class of connected patch array antennas that may include various construction materials.
Lymph node status is the most reliable prognostic indicator for patients with melanoma and breast cancer. Australia has the highest rate of melanoma in the world. Breast cancer is the most common cancer among woman. Determining cancer status in lymph nodes is particular useful for these two cancers. This article provides a review of current medical imaging techniques in the literature. Several studies...
This paper presents a novel, easy-to-fabricate and operate, single-layer leaky-wave antenna (LWA) that is capable of digitally steering its beam at fixed frequency using only two values of bias voltages, with very small gain variation and good impedance matching while scanning. Steering the beam of LWAs in steps at a fixed frequency, using binary switches, is investigated, and a new half-width microstrip...
A printed monopole antenna with O-shaped ground plane presented in this paper covers FDD/TDD-LTE, DCS, PCS, and 2.4 GHz ISM bands for smartphone applications. The antenna has a wide impedance bandwidth of 2.02 GHz (1.12–3.14 GHz) with a voltage standing wave ratio of 3:1, given the overall antenna size is 40 × 15 × 0.035 mm3. Peak gain of the proposed antenna is 5.30 dBi with a gain variation of less...
This paper highlights recent developments in antennas with full ground planes, which have been designed for Wireless Body Area Networks (WBANs). These antennas are designed to provide single/dual band operation in 2.4GHz industrial, scientific and medical (ISM) band and 4.9GHz public safety wireless local area network (WLAN)/5GHz IEEE 802.11 WLAN bands. They have significant advantages of compactness,...
A simple leaky-wave antenna (LWA) array is presented here radiates in the boresight direction. It is based on uniform half-width (HW) microstrip leaky-wave antennas (MLWAs). Uniform HW-MLWAs usually radiate a fan-shaped beam with a beam direction near boresight at lower frequencies and near endfire at higher frequencies. One of the main challenges of uniform LWAs is to make them radiate toward the...
We describe a SKA hardware component model that includes various concepts for achieving a wide field-of-view (FoV) as desired for survey speed. Costs for each of the components in the model are derived and in some cases optimum parameters are estimated. The model identifies components of major cost and allows comparison of the relative costs of the wide FoV concepts.
Selected results of the optics analysis of the proposed offset Gregorian reflector with Phased Array Feed (PAF) are presented. The approach used to analyze the phased array feed with the Gregorian reflector is described.
A simple array of half-width (HW) microstrip leaky-wave antennas (LWAs) radiates a conical beam around the boresight. Uniform microstrip LWAs usually radiate a fan-shaped beam with a beam direction near boresight at lower frequencies and near endfire at higher frequencies. Six HW-MLWAs terminated by matched loads are used in this array. The whole array is on a single substrate, where the LWAs are...
A low noise amplifier (LNA) with 30 K noise temperature over a wide frequency range from 0.9 to 3.5 GHz is presented. The LNA to be described is suitable for high frequency connected arrays such as Phased Array Feeds (PAFs) operating in the 0.5 to 4 GHz frequency range. The LNA is implemented with unpackaged transistors. It combines single ended configurations to form a balanced amplifier with differential...
This paper presents a slot-loaded half-width microstrip leaky-wave antenna (MLWA) for fixed-frequency beam scanning. Digital switches are used in the design for controlling the beam direction at a fixed-frequency. Dynamically changing the ‘On’ and ‘Off’ states of the switches, the main beam of the antenna is steered in discrete steps. Addition of slots in the microstrip line results in shifting of...
This paper presents a technique to produce two symmetrical side beams from a simple microstrip leaky-wave antenna (MLWA) and to steer them. Two beams are generated by using two vertical conducting walls along the microstrip line, each located one-third the width away from each edge. The directions of the main beams are controlled by changing the reactance profile between the free edges of the microstrip...
The use of flat dielectric surfaces having a radial gradient of permittivity is investigated for use as superstrates in Fabry-Perot cavity (FPC) antennas. The use of such surfaces results in a varied reflectivity within the FPC and makes the boresight emissions spatially coherent. This results in a significantly enhanced gain-bandwidth product of a FPC antenna using only a single feed. The key advantage...
Lens-like superstrates designed to exhibit a spatial reflectivity map are studied for use as the partially reflecting surface in Fabry-Perot cavity antennas. Profile reduction is obtained by using only a single dielectric layer of such surfaces which is found to provide improved performance than the multi-layered superstrates. The use of such surfaces results in a varied reflectivity within the cavity...
Various challenges have arisen in the measurement of phased array feeds for radiotelescopes. We focus here on measuring the equivalent noise temperature and the sensitivity of these feeds. We outline the differences between characterizing phased array feeds compared with traditional single horn feeds and provide results from our experience in developing phased array feeds for the Australian Square...
We describe the design and analysis of a broadband low noise amplifier suitable for connected array phased array feeds (PAFs) operating in 0.7 to 3 GHz frequency range. The LNA is a designed in a single ended configuration and analysis is carried out to form a differential amplifier with noise match impedance of the order of 300 Ω. Predicted results show a noise temperature of less than 21 K over...
The decomposition of reversed time (DORT) method is a promising algorithm for microwave breast cancer imaging. However when DORT is applied to breasts with high percentage of glandular tissues, its performance decreases due to differences in the dielectric properties of the physical and computational media. We propose a new method of deriving pair wise permittivities by using the received scattered...
A half-width microstrip leaky-wave antenna (HW-MLWA) array for radiation towards broadside is presented. One of the main challenges of leaky-wave antennas is to radiate towards broadside. This can be achieved by a half-width MLWA array. Four uniform HW-MLWAs, terminated by 50O SMA coaxial loads, are used in the array. The full-wave numerical simulations show the ability of the proposed HW-MLWA array...
We describe analysis and design of two low-noise amplifiers (LNAs) suitable for connected array Phased Array Feeds (PAFs) operating in the 0.4 to 2 GHz frequency range. The LNAs combine single ended configurations to form balanced amplifiers with differential signal- and noise-match impedances in the order of 300Ω. Simulation results show noise temperatures of 20 K to 30 K for the 0.45 to 0.9 GHz...
We formulate a successive projections approach to computing field scattering by inhomogeneous electromagnetic media. Solutions for the projections are derived in the space and space-harmonic domains. The key projections are shown to be expressible in terms of homogeneous-media Green's functions with complex wavenumbers, indicating possibilities for evaluation using existing representations and parallel...
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