Learn More
Placing the radiators of antenna arrays closer than aggravates the problem of power mismatch. Based on efficiency considerations, a general analysis of this effect is presented, putting forward a simple tool to quantify, compare, and optimize the performance of antenna arrays. This analysis is not restricted with respect to the number of radiators or the(More)
In ordinary antenna arrays, the spacing between radiators is usually chosen lambda/2. In order to use antenna arrays in small mobile platforms, the overall dimensions and, hence, the radiator separation, must be reduced, which aggravates the problem of mutual coupling between radiators. Results are highly distorted beam patterns and greatly reduced(More)
Mutual coupling has negative impact on the radiation properties of compact antenna arrays when the spacing of individual radiators is considerably closer than half a wavelength. We have previously put forward a description of the radiation efficiency of an arbitrary antenna array in terms of orthogonal radiating eigenmodes. The present publication(More)
We describe the design, simulation, measurement, and application of ultra-wideband antennas for the investigation of physiological signatures and navigation for magnetic resonance imaging of moving targets. The interdependence between size, frequency dependent radiation patterns, signal acquisition, and the compatibility with strong magnetic fields are(More)
Ultra-wideband sensing begins to play an important role in biomedical diagnostic systems. Promising and relevant applications include remotely monitored vital functions as well as the characterization of tissues and organs. The acquisition of such physiological signatures requires small and radiation-efficient antennas, designed for ultra-wideband frequency(More)
Decoupling and matching networks may be used to improve the performance of compact antenna arrays where mutual radiator coupling has caused a degradation of the diversity capabilities. A popular network consists of a 180deg rat-race directional coupler, which decouples the antenna ports, followed by impedance matching networks at each port. Researchers,(More)
We have developed a compact and mechanically robust reconfigurable microwave switch matrix as well as peripheral components for satellite applications using the low temperature co-fired ceramics technology (LTCC). In order to verify the technology for space applications, we combined these components to build a system that enables automated verification of(More)
The unlicensed frequency range around 60 GHz is optimally suited for wireless high-data rate transmission systems. To exploit this potential, the interactive design and characterisation of antennas, transceivers, and signal processing algorithms tailored to the specific demands of the intended application is required. In terms of the air interface, the high(More)
The focus of this paper is the miniaturisation of antenna arrays, to exploit diversity schemes for mobile communications. The main parameter determining the size of an array is the spacing between adjacent radiators, which is usually chosen to be half a wavelength. Reducing the spacing introduces mutual coupling between the elements and, hence, a(More)
This paper describes the requirements for, and successful implementations of, a reconstruction filter suitable for a class-S power amplifier system. Beside tailoring the pass-band and the stop-band, mode and impedance matching to the push-pull switch-mode amplifier, driven by a delta-sigma modulator, over a wide bandwidth are crucial to sustain a high(More)