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RFID is a reliable technology to identify objects wirelessly. Medical devices are subjected to various tests and a lot of time is spent to search for the corresponding devices. The high personal costs make this a quite expensive venture. Launching wireless tagging systems in the clinical environment is still difficult, because many devices can be sensitive to interferences caused by the electromagnetic...
A dual-band dual-polarized compact antenna array is designed for intended use in robust global navigation satellite receivers. The four-element antenna array is connected to an eigenmode-based decoupling and matching network to compensate for the radiation efficiency degraded by mutual coupling. The resulting eigenmodes of the array are then fed to an RF-IF front-end for down-converting, filtering,...
Microwave frequency discriminators based on six-port receiver architecture are becoming increasingly popular for a multitude of applications in sensing and identification of spectrum holes, e.g., for cognitive radio applications. One of the key limiting factors of a six-port receiver is its narrow dynamic range which is mainly limited by the use of square-law diode detectors in the primary detector...
Where unused frequency bands become scarce, their resourceful handling is essential. Consequential, to enable best use of various frequency bands with a single device, the need for reconfigurability emerges. Complementary to already existing technologies, a novel transistor-based circuit is introduced that makes passive, reciprocal, electronic reactive tuning possible. Ultimately, a tuneable inductance...
This paper presents a compact, low-cost spectrum sensor with very large dynamic range, to detect arbitrarily modulated input signals with respect to identifying the spectrum holes available for cognitive radio applications. The sensing technique is based on the combination of a tunable pre-selector filter with a four-port circuit consisting of logarithmic detectors. Since the four-port is a passive...
3-D TLM approach based on the cylindrical grid and enhanced with the compact wire model has been used for modelling of an inverted circular microstrip patch (IMCP) antenna with the coaxial feed. The simulated results have been compared with the measured results and rectangular grid based TLM results. Additional, the influence of the air gap height on the resonant frequency of the IMCP antenna has...
A novel linearization technique for RF power amplifiers is presented in this paper. The proposed technique uses the modified baseband signal that modulates the fundamental carrier second harmonic. This additional signal processed for linearization is then injected, together with the fundamental useful signal, at the input of the amplifier transistor. Also, a prepared signal for linearization is inserted...
This paper focuses on the investigation of the dynamic range of a single-pole quadrouple-throw P-I-N-diode integrated switch circuit which is the basic building block of a 4 × 4 re-configurable microwave switch matrix for Ka-band satellite downlink (17 – 22 GHz). The noise figure and the level of third order intermodulation products, in this case passive intermodulation, which can interfere with in-band...
This paper presents designs for reconstruction filters suitable for a class-S power amplifier operating at a centre frequency of 900 MHz. Previously, we presented analytical comprehensive comparison of doubly and singly terminated filters and proved mathematically that only singly terminated filters owing to their constant input impedance can fulfil the requirements of current-mode switching amplifiers...
This paper presents the design of a reconstruction filter for a class-S power amplifier. Previously, a few doubly terminated filters for a switched-mode amplifier system were presented, but measurement results showed significant ripples up to 3 dB in output power. This effect can be explained by the current mode final stage acting like a current source with infinite internal impedance, thus demanding...
The need for efficiency improvement of conventional class-AB-amplifiers when used with non-constant envelope modulations has set up interest in introducing switch mode amplifiers in the GHz operating frequency range. In order to be suitable for the amplification of arbitrarily modulated signals, a one-bit modulator is required at the input of the switch mode amplifier. Beside bandpass delta sigma...
This paper describes the realisation of an antenna array system consisting of three, quarter-wavelength spaced, monopoles and a passive network. This compact planar network decouples and matches the antenna array, in order to prevent gain reduction. At the same time, the network forms orthogonal radiation patterns at the system ports, which divide the space into three different sections. The described...
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