Conventional UWB Research Articles

A Double Combined Symmetric T-shaped Slots and Rotated L-shaped Strips Inspired UWB Antenna for C and X-band Elimination Filters

In this paper, we present a modified UWB antenna with hexagonal slotted ground plane inspired with a double combined symmetric T-shaped slots and dual rotated L-shaped strip for dual band notched characteristics. Initially, the operating frequency range is from 3GHz to 12 GHz. To eliminate the unwanted C-band (3.625-4.2GHz) and the entire uplink and downlink of X-band satellite communication systems (7.25 -8.39 GHz) frequency bands, we are investigating the conventional UWB patch antenna and loaded it with a mentioned strips and slots respectively. The performances of the antenna are optimized both by CST Microwave Studio and Ansoft HFSS. To further analyze the parametric effects of the slots and strips, the surface current distribution is presented and discussed. The antenna gain versus frequency gives an acceptable value except the notched band regions, these values are reduced from its normal to be a negative in the notched bands (3.625-4.2GHz) and (7.25 to 8.39 GHz).

A C-Band Planar Metamaterial-Inspired Antenna Employing a Hexagonal Cell Periodic Structure

In this paper, a metamaterial inspired antenna to operate in the C-band is designed, fabricated, and characterized. The structure is based on the metamaterial tripolar array, to obtain a better gain, bandwidth, and frequency resonance when compared to a conventional circular UWB antenna with same structural characteristics. Simulation and experimental results show an increase of about 32% on the bandwidth and 9% on the gain with a satisfactory radiation pattern.

Reconfigurable antenna using capacitive loading to Artificial Magnetic Conductor (AMC)

ABSTRACTA dual band Artificial Magnetic Conductor (AMC) with capacitive tuning of reflection phase at lower band frequency is proposed. The AMC operates at upper band of fixed frequency at 5.8 GHz while the lower band reconfigurable frequency is from 2.5 GHz up to 3.1 GHz. The simulated reconfigurable frequencies are 2.5, 2.62, and 3.10 GHz. The corresponding resonance structure for each band is circular patch and circular slotted ring with single capacitor per AMC unit cell. Subsequently, the AMC is incorporated with conventional UWB antenna. The effects of AMC capacitive tuning to UWB antenna performance are studied in terms of frequency reconfigurability, gain, and radiation patterns. Measurement is also carried out for the reflection coefficient and radiation patterns. Parametrical studies of the antenna such as the misalignment between the top and bottom substrate layers, air gap between the substrate layers, and capacitance tolerance of the capacitor to the reflection coefficients are also discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2422–2429, 2016

Self-sustained UWB Sensing: A Link and Energy Adaptive Approach

Energy efficiency is a challenging issue in autonomous and distributed sensing systems, especially when these systems are powered by renewable energy sources. In this paper, we present a link and energy adaptive UWB-based sensing technique to improve the detection time coverage and detection range coverage for self-sustained embedded applications. The basic idea is derived from the fact that domain-specific information in such applications is often available. Thus, by jointly exploiting the link information between the transmitter and receiver of the UWB pulse radar, and the non-deterministic characteristics of the renewable energy, the proposed technique dynamically adjusts the pulse repetition frequency of the UWB radar to enhance the sustainable operation under the unreliable energy supply. The overhead of the proposed technique is negligible as compared with the overall energy consumption of the UWB pulse radar. It was demonstrated that the proposed technique can achieve much better detection time coverage and detection range coverage than the conventional UWB radar. The proposed technique is also insensitive to many practical issues such as the limited battery capacity.

Adaptive space-time-frequency-coded UWB system for wireless body area network

Wireless body area networks (WBAN) emerge as one of the main research streams for future wireless communications. One of the candidates for the WBAN physical layer is multiband orthogonal frequency division multiplexing ultra-wideband (MB-OFDM UWB) technology. However, despite its high data rate feature, it performs poorly in the very dispersive WBAN channel. To improve its performance, this paper proposes two novel mechanisms. First, the space-time-frequency coding (STFC) is introduced into MB-OFDM UWB system in order to enhance the diversity order, resulting in a substantial improvement in the average error performance compared to the conventional MB-OFDM UWB system. Nevertheless, the performance is very sensitive to the body orientation towards the transmitter due to the body shadowing effect. Secondly, to improve further the performance of the proposed STFC MB-OFDM UWB system in all body directions, we propose an adaptive scheme that changes the modulation, STFC coding rate, and constellation power. Simulations confirm that an additional improvement in the order of 1 to 3 dB is achieved by the adaptive system. This improvement practically means a possible 12.5% to 50% reduction of the power consumption, which may also result in smaller size of WBAN devices.

Energy-adaptive Pulse Amplitude Modulation for IR-UWB Communications Under Renewable Energy

Impulse Radio Ultra-wideband (IR-UWB) technique has long been recognized for its unique carrierless operation as compared with other communication techniques. The simple and low-cost structure offers great advantages for self-powered embedded wireless systems, in which energy efficiency is a challenging issue due to the fact that most renewable energy sources only offer limited and unstable power supply. In this paper, we present an energy-adaptive Pulse Amplitude Modulation technique for self-powered IR-UWB based communication systems to improve data rate and or time coverage. The basic idea is derived from the fact that domain-specific information in such applications are often available; thus, by jointly exploiting the wireless channel conditions and the non-deterministic characteristics of renewable energy sources, the proposed technique dynamically adjusts the modulation level to enhance the sustainable operation under the unreliable energy supply. Simulation results demonstrate that the proposed technique achieves a much higher data rate and better time coverage than conventional UWB systems. The proposed technique is also insensitive to many practical issues such as the battery aging effect.

A Low Voltage High Gain Transformer Noise-Canceling Current Mode Ultrawideband CMOS Low Noise Amplifier

This paper presents a novel current mode differential UWB LNA. A common-gate stage with transformer realizes a low noise input matching and produces a current gain. The output of the LNA is differential current, which can avoid the current-to-voltage conversion. The LNA is simulated with TSMC 0.18 μm RF CMOS process. Simulation results show that the max noise figure is only 2.65 dB, transconductance gain is larger than 18.7 dB, input reflection coefficient is lower than -9.9 dB, and third order input intercept point is about 2.8 dBm over 3–5 GHz. With a voltage of 0.8 V, the power consumption is 11 mW. A comparison with conventional UWB LNA shows that this LNA has advantages of low voltage, low noise, high gain, and high linearity.

UWB PRINTED SLOT ANTENNA WITH IMPROVED PERFORMANCE IN TIME AND FREQUENCY DOMAINS

A microstrip-fed slot antenna is proposed for short-range UWB communication. First, the characteristics of a conventional circular monopole UWB antenna, as a representative of a class of UWB antennas seen in the literature, are examined in time (pulse-shape) and frequency (re∞ection and transmission coe-cients) domains. From these measurements, certain limitations of this class of antennas are brought out, which are not widely recognized. We then demonstrate that with proper optimization the traditional microstrip-fed slot antenna overcomes these defects and is an excellent candidate for UWB communication systems. This claim is justifled with measurements in time domain and frequency domain.

Dual-mode impulse radio ultra-wideband transmission for body area networks

A dual-mode impulse radio ultra-wideband (IR-UWB) system, which combines body channel communication for wearable on-body transmission with conventional UWB communication for in-body to on-body transmission, is proposed. The basic system structure is presented, and the path loss characteristics are derived based on numerical analysis and measurement. Moreover, through a bit error rate performance analysis, the required transmit power against communication distance shows the feasibility for on-body and in-body transmissions at a data rate of at least 10 Mbps.

TOA Estimator for UWB Backscattering RFID System with Clutter Suppression Capability

Time of arrival (TOA) estimation in multipath dense environment for UWB backscattering radio frequency identification (RFID) system is challenging due to the presence of strong clutter. In addition, the backscattering RFID system has peculiar signal transmission and modulation characteristics, which are considerably different from conventional communication and localization systems. The existing TOA estimators proposed for conventional UWB systems are inappropriate for the backscattering RFID system since they lack the required clutter suppression capability and do not account for the peculiar characteristics of backscattering system. In this paper, we derive a nondata-aided (NDA) least square (LS) TOA estimator for UWB backscattering RFID system. We show that the proposed estimator is inherently immune to clutter and is robust in under-sampling operation. The effects of various parameter settings on the TOA estimation accuracy are also studied via simulations.

Quasi-orthogonal space-time-frequency codes in MB-OFDM UWB

Quasi-orthogonal space-time-frequency codes (QOSTFCs) will be examined in this paper to advance either data rate or error performance in recently proposed space-time-frequency coded multiband OFDM Ultra-wideband (STFC MB-OFDM UWB) communication systems. It is shown that QOSTFCs can provide significantly better error performance, compared to the conventional MB-OFDM UWB (without STFCs) and to the orthogonal STFCs (OSTFCs) of the same order, at the same data rate, without increasing the total transmission power. Another form of the enhancement would be that QOSTFCs can provide higher data rates with the same error performance, compared to OSTFCs.

Performance Analysis of Single-User Ultra-Wide Band Impulse Radio (UWB-IR) with Super-Orthogonal Turbo Codes (SOTC)

Low-complexity low-rate super-orthogonal turbo codes (SOTC) are proposed in this work to replace the implicit repetition code (RC) in ultra-wide band impulse radio (UWB-IR) systems to improve the transmission range and system throughput. Various receivers, including the matched-filter and the RAKE receivers, are examined for data detection in the additive white Gaussian noise (AWGN) channel and the indoor IEEE 802.15.3a channels. The performance of SOTC-coded UWB with perfect and imperfect timing and channel information is analyzed and corroborated by computer simulation. It is demonstrated that the SOTC-based UWB-IR system can achieve significant performance improvement over the conventional direct-sequence UWB (DS-UWB) system encoded by RC over both ISI and ISI-free channels.

UWB radars in medicine

Applied research on biomedical applications of UWB radar is targeted to the identification of the possible new devices made possible by the technology, to the design and development of those devices, and to the clinical testing of the systems obtained. Applications can be divided into two main sectors according to the frequency range used. For the conventional UWB radar microwave region: cardiac biomechanics assessment; chest movements assessment OSA (obstructive sleep apnoea) monitors; soft-tissue biomechanics research; heart imaging (Holter type echocardiography); chest imaging. Together with systems for: cardiac monitoring; respiratory monitoring; SIDS (sudden infant death syndrome) monitor; vocal tract studying. If an IR laser diode is used as the antenna, a more common radar is obtained (actually a hybrid between a narrow band and a wide band radar) which emits a short packet of electromagnetic waves whose echoes are sampled using conventional UWB receiver equipped with a PIN photodiode. Possibilities include: non-invasive biochemical study of soft tissues, non-invasive study of metabolic processes, and IR spectral imaging.