Anthony K. Brown

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Propagation measurements using a large array are used to study the angle of arrival (AOA) across the ultrawideband (UWB) frequency range of 3.1 to 10.6 GHz. A two-dimensional Unitary ESPRIT algorithm is employed to give a high resolution estimation of AOA including both the azimuth and elevation angles of multipath components. The frequency dependence of(More)
This paper presents a low profile ultrawideband tightly coupled phased array antenna with integrated feedlines. The aperture array consists of planar element pairs with fractal geometry. In each element these pairs are set orthogonal to each other for dual polarisation. The design is an array of closely capacitively coupled pairs of fractal octagonal rings.(More)
The statistics of multipath arrival in an indoor multipath channel have been obtained based on a 3-D ray-tracing model. It is found that a Rayleigh distribution is a reasonable approximation assuming all multipath components below a -10 dB threshold with respect to the peak power path are neglected. The number of arrival paths in a small time interval (used(More)
Null steering is an important beam-forming technique for phased antenna arrays in general particularly in applications involving high interference. In radio astronomy, where the signal of interest may be much weaker than interference (particularly from manmade sources) a severe limitation may occur on the system noise temperature, dynamic range and(More)
This paper presents the radiation pattern of a low-frequency FR-ORA array based on the low-cost planar surface near-field to far-field measurement system. The far-field pattern was obtained from near-field measurements and by using a Fast Fourier Transformation (FFT) algorithm. This technique was used to characterize the radiation pattern of a prototype 4(More)
Ultra-wideband capacitively coupled phased array antennas for low and mid frequency radio astronomy are presented. Two distinct and novel broadband techniques are employed for the candidate current sheet models. One of the arrays is designed to operate from 250 MHz to 1.3 GHz while the other functions from 50 MHz to 400 MHz. The radiating arrays comprise(More)
A dual polarized aperture array consisting of Octagonal Ring Antennas (ORA) operating in the AA-mid frequency range between 400 MHz and 1.4 GHz has been developed for the Square Kilometre Array. A finite array with the aperture size of 1m × 1m had been fabricated. The subarray elements of the finite array are connected to self-developed LNAs or(More)
Differential front-end design presents a good prospect to be integrated with differential beamformer inputs without a transformer needed otherwise for a single-ended front-end design. A front-end solution with a complete differential configuration is presented. The potential advantages of this design are: planar antenna elements mean a lower cost;(More)
Broadband phased arrays are being used in a wide number of imaging application in radio astronomy and radar. To improve the cost effectiveness, the system must meet the minimum performance requirements with the fewest number of elements. Since the array geometry affects many aspects of the overall performance such as directivity, sidelobes, and mutual(More)