Paul A. Warr

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A new frequency-reconfigurable antenna architecture is presented, in which a dielectric fluid is pumped into a cavity behind the antenna to change its resonant frequency. The continuous tuning provided by the changing fluid volume allows the resonant frequency to be adjusted to any value within the tunable range. This tuning method does not affect the power(More)
A highly linear Low Noise Amplifier (LNA) using a flexible feedforward linearisation scheme is described. The wideband LNA is designed for use in the frequency spectrum between 1 and 2GHz. It has a tuneable linearity profile which allows it to be adjusted for wideband moderate linearity or narrowband high linearity. The linearity can be tuned so a wideband(More)
In this note a formal proof is given to an observation that the perturbational response of a planar resonator, which can be modelled as a cavity with magnetic side-walls, is the dual of the behaviour of a classical cavity with electric walls. This perturbational duality is observed even though the respective boundary types are not exactly dual. This(More)
This paper presents a chaotic oscillator-based binary phase-shift keying (CO-BPSK) modulation scheme, exploiting the chaotic dynamics to achieve carrier phase inversion. A basic analytical expression is derived for the bit error-rate (BER) under additive white Gaussian noise (AWGN) channel conditions, and a baseband complex envelope simulation technique(More)
Within neural monitoring systems, the front-end amplifier forms the critical element for signal detection and preprocessing, which determines not only the fidelity of the biosignal, but also impacts power consumption and detector size. In this paper, a novel combined feedback loop-controlled approach is proposed to compensate for input leakage currents(More)
Both Software Defined Radio and Cognitive Radio require a flexible transceiver front end. This paper introduces solutions to two important features of such a device; the antenna and the filter. These are both microwave resonant structures and so share design trade-offs and restrictions; in this application they must both offer some degree of tunability or(More)
The front-end amplifier forms the critical element for signal detection and pre-processing within neural monitoring systems. It determines not only the fidelity of the biosignal, but also impacts power consumption and detector size. In this paper, a combined feedback loop-controlled approach is proposed to neutralize for the input leakage currents generated(More)