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In this paper, a two element antipodal Vivaldi antenna array in combination with an ultra-wideband (UWB) Wilkinson power divider feeding network is presented. The antennas are placed in a stacked configuration to provide more gain and to limit cross talk between transmit and receive antennas in radar applications. Each part can be realized with standard planar technology. For a single antenna element,...
A small-size, low-profile, and planar integrated antenna is presented. This antenna is fed by a microstrip line and built on a PTFE substrate with only 20mm*46mm and the overall size of the radiating element is 15mm*16mm. A semicircular slot resonator and a split ring slot resonator are embedded in the radiating patch. The bandwidth of this antenna is 2.25–11.25GHz which covers UWB (IEEE 802.15.3a,...
A detection algorithm is introduced for breast cancer diagnostics. A coaxial skin+breast tissue phantom has been used for numerical evaluations. The algorithm has been validated with both ideal and realistic sources. In particular, an antipodal Vivaldi antenna operating in the frequency range 1 – 2.5 GHz has been properly optimized for this application. A 5 mm thick tumor has been correctly detected...
Site-specific ultrawideband propagation modeling involves dealing with frequency variations of the propagation mechanisms and antenna patterns in the ray tracing program. Typically, electromagnetic field calculations have to be performed in a lot of frequencies to accurately construct the frequency response of the channel at a receiving point. This imposes a heavy computational burden on ray tracing...
We present an extension of an existing outdoor UWB scatterer detection algorithm [1], [2], making it usable for indoor scenarios. The algorithm is extended with the capability to find virtual sources, which can explain reflections from extended, plane surfaces. The extension thus removes the restriction to just single-bounce signal paths. Single-bounce scatterers, as well as virtual sources extracted...
In this paper, we propose a new bidirectional stacked microstrip dipole antenna with a multilayered disk array structure (MDAS) for a high gain WLAN application. In the proposed structure, two identical MDAS are attached on the both sides of a dipole exciter which is composed of two linearly polarized stacked microstrip patches placed back to back and fed with balanced input power using unbalanced-to-balanced...
Impulse-radio UWB (IR-UWB) transceivers are quite interesting since they can achieve high data rate while consuming low power. But UNII Band interferers are a serious problem for using the whole spectrum in IR-UWB. Also the short range of UWB is a serious limitation to this technology. Here we have proposed a solution to overcome both of the above mentioned problems. Matched filter concept shapes...
Beamforming is one of the key technique for 60GHz wireless system to work at this millimeter-wave region with high propagation path loss. In IEEE 802.15.3c standard, a codebook based analog beamforming mechanism is adopted for its simplicity and feasibility. However, this simple beam sweep mechanism may not work properly in the presence of Co-Channel Interference (CCI) when dense spatial reuse is...
The uncoordinated nature of impulse radio ultrawide bandwidth (UWB) transmissions leads to multiple-user interference (MUI) at each receiver. Due to use of a repetition code and multipath propagation, a Rake receiver has many partial decision statistics available for use in forming a symbol decision. Novel time-hopped UWB Rake receiver structures have been designed that aim to mitigate MUI by sensing...
This paper discusses the interfering signal detection technique for DAA (Detection And Avoidance) operation of an UWB (Ultra Wideband) systems. To detect the interfering signal, sub-band pulses of a multi-carrier type are prepared as template waveform in the detector. The received signal is correlated with the sub-band pulses and the correlation values are compared with the threshold value. The proposed...
We present a communication scheme aimed to improve robustness of impulse-UWB energy-detector receivers in the presence of narrowband interference. We first show that for this receivers, the matched filter waveform depends on interferer phase and amplitude, and it can become null for jammers with carrier frequency close to that of the desired channel. We then show that by multiplying the transmitted...
Ultra-WideBand (UWB) system shares the same frequency band with the other wireless communication systems. It is, however, necessary to detect the presence of the other wireless systems as primary systems in order to avoid interference to them. For this purpose, the energy detection method detects the presence of the primary system based on the observed energy at individual UWB device. On the other...
A novel super compact microwave ultra-wideband (UWB) bandpass passive filter (BPF) is proposed using S-shape broadside-coupled striplines. A theoretical model is presented to analyze the scattering and coupling mechanism of the suggested filter. To eliminate interference, a tunable integrated notched-band filter is also introduced using a new technique. A group delay of 0.08 ns within the passband...
In this work we present a low-complexity, ultra-wideband (UWB) pulse generator which complies with the Sub-GHz band in FCC regulation. This pulse generator uses a simple common emitter amplifier followed by RC high-pass filter as a differentiator to generate the monocycle pulse directly. The circuit provides a monocycle pulse when activated by a ramp edge of an external trigger signal provided by...
In this paper, we present a step recovery diode (SRD) based ultra-wideband (UWB) transmitter. No custom integrated circuits (ICs) are used, and all of the components are commercially available off-the-shelf products, targeting low-cost and fast turn-around. UWB pulses are generated using SRDs, and pulse position modulation (PPM) is implemented by a microcontroller. Detailed analysis and equations...
The use of Schottky diodes as high-speed variable impedance loads in six-port modulators are proposed and analyzed in this paper. The impedance dependency of diode parameters and local oscillator power are investigated by theoretical analysis and simulations. A prototype for a direct carrier six-port modulator using Schottky diodes for impedance generation is designed and fabricated for a center frequency...
A fully integrated power-efficient CMOS pulsed ultra-wideband (I-UWB) transmitter for biomedical applications operating in the 3 – 5 GHz band is implemented in a 65 nm CMOS technology. The UWB transmitter adopts a low-complexity ring oscillator-based pulse generator architecture and pulse-position-modulation (PPM) for increased power efficiency and minimal silicon area. The transmitter consumes zero...
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