Lower Ultra-wideband Band Research Articles

Design and Device Mismatch Analysis of CSS–UWB Pulse Generator

This paper presents the design of a Chirp Spread Spectrum (CSS), ultra-wideband (UWB), pulse generator (PG) and device mismatch impact on its performance. The proposed CSS-PG is built using a differential ring oscillator (RO) controlled by a ramp generator, allowing varying linearly the pulse frequency with time over the CSS pulse duration. Device mismatches and random variations during integrated circuit manufacturing are the most critical imperfections in high precision differential UWB voltage controlled RO circuit. These mismatches lead to behavioral variations of the PG. The proposed CSS-UWB-PG is designed and analyzed using CMOS 0.18[Formula: see text][Formula: see text]m technology. The CSS-PG presents an output swing of 266[Formula: see text]mV Vpp for 20[Formula: see text]nsec and consumes 1.72[Formula: see text]mW for a PRF of 10[Formula: see text]MHz. The simulated PSD covers the UWB low band from 3[Formula: see text]GHz to 5[Formula: see text]GHz and complies with the FCC regulations. For [Formula: see text] mismatch, the simulation results show a maximum relative accuracy on oscillation frequency and phase noise of 3.43% and 6.9%, respectively. Monte Carlo and process simulation are performed to study the impact of the random parameter variation on this CSS-PG. Theses simulations show the robustness of the proposed design as the PG PSD is still inside the FCC-UWB mask and its bandwidth is greater than 500[Formula: see text]MHz.

Small-Sized UWB MIMO Antenna With Band Rejection Capability

A very compact and small sized 2-element planar Ultra Wide band (UWB) antenna having high isolation with band rejection characteristics designed on a FR4 substrate (23 × 26 × 0.8 mm 3 ) is presented in this paper. Each antenna element have a rectangular stepped-slot and a z-shaped slot, both etched in ground plane. The rectangular slot, proximity fed by a 50 Ω micro-strip transmission line, acts as a main radiator while z-shaped slot acts as a filter for rejecting the full WLAN band (5.15-5.85 GHz). Use of an inverted T-shaped slot near top end of ground plane improves isolation more than 24.5 dB in lower UWB band i.e. 3-5 GHz, while the rectangular vertical slot etched at center of the ground plane near the bottom edge reduces the mutual coupling at lower as well as at higher UWB band i.e. 5 - 10.6 GHz. Both measured and simulated results are presented which are found generally in good agreement.

Dual-Band Shared-Aperture UHF/UWB RFID Reader Antenna of Circular Polarization

A dual-port, dual-band, and circularly polarized (CP) radio frequency identification reader antenna is designed to operate at both ultrahigh frequency (UHF) and lower ultra-wideband (UWB) bands for indoor positioning systems. In conjunction with a properly selected quadruple feed network, a shared aperture using the concept of hybrid mode is utilized for broadening the antenna bandwidth. The concept is demonstrated to achieve a high gain, wideband, and CP operation within a low profile. The measured overlapping 3-dB axis ratio (AR) bandwidth and 10-dB impedance bandwidth for the UHF band ranges from 0.918 to 0.926 GHz with a minimum in-band antenna gain of 9 dBic. The measured overlapping 3-dB AR bandwidth and 10-dB impedance bandwidth covers from 3 to 5.2 GHz with a minimum in-band gain of 9 dBic in the lower UWB band (i.e., 3.1–4.8 GHz). The gain suppression near the two wireless local area network bands (i.e., 2.45 and 5.8 GHz) is more than 20 dB. The isolation between two ports is larger than 25 dB over the UHF and lower UWB bands, respectively.

A compact frequency‐reconfigurable fractal UWB antenna using reconfigurable ground plane

AbstractIn this article, a compact frequency reconfigurable ultrawideband (UWB) antenna having switchable multiple bands is presented. The reconfigurable multiple bands include UWB band, lower UWB band, middle UWB band, and one dual band having lower and upper UWB bands. Multiple p‐i‐n diodes are used in the slotted ground plane which helps to achieve frequency reconfigurability. The desired compactness and wider operational bandwidth is obtained in the antenna design with the help of Sierpinski fractal geometry. Moreover, it helps in enhancement of the radiation characteristics that assist us to get omnidirectional radiation pattern. It has a compact size of 24.5 mm × 20 mm.

Soil Effects on the Underground-to-Aboveground Communication Link in Ultrawideband Wireless Underground Sensor Networks

Wireless underground sensor networks (WUSNs) is an emerging area of research. They are used in many applications from intelligent irrigation to security and assisted navigation. WUSNs mainly use narrowband systems working in the frequency range below 1 GHz and, therefore, suffer from a poor localization capability and large-sized antennas. The use of impulse radio ultrawideband (UWB) technique allows alleviating these drawbacks. In this letter, the impact of soil on UWB underground-to-aboveground communication link is studied experimentally. More specifically, the effects of the orientation of the buried antenna and burial depth and soil moisture are investigated. The experimental results show that, at 7 GHz, additional attenuations of 10, 34, and 40 dB are noted for depointing the underground antenna by 90°, increasing the depth from 0 to 30 cm and raising the soil moisture from 0% to 20%, respectively. Burial depth lower than 30 cm or soil moisture lower than 20% allow getting acceptable received signal strength (superior to –100 dBm) for communication and localization, particularly in the UWB low band (3.1–5 GHz). The obtained results bring out the feasibility of UWB WUSN.

A novel a-shaped monopole-like slot antenna for ultrawideband applications

A novel A-shaped monopole-like slot antenna is presented. The proposed antenna consists of a A-shaped radiating patch in place of the conventional monopole patch antenna to achieve ultrawideband (UWB) frequency. The ground plane is also modified by cutting rectangular slots to resonate at lower band of UWB. The antenna is practically fabricated and simulated. Measured results shows a good agreement with simulated results. The prototype with an overall size of 25 × 25 × 1.6 mm3 achieves good impedance matching, almost constant gain, stable radiation patterns, and constant group delay over an entire operating bandwidth. The designed antenna offers a measured bandwidth of 9.6 GHz (2.9–11.5 GHz) which covers entire UWB band. The proposed antenna has a compact size, good radiation characteristics, ultrawide bandwidth, and good time-domain behaviors to satisfy the requirement of the current wireless communication systems. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1826–1829, 2014

An M‐shaped monopole‐like slot UWB antenna

ABSTRACTAn M‐shaped monopole‐like slot Ultra wideband (UWB) antenna is proposed for UWB applications. The proposed antenna usages, an M‐shaped radiator in place of the conventional monopole patch antenna to achieve UWB frequency. The ground plane is also modified by cutting rectangular slots. Therefore, the ground plane works like a radiator that resonates at lower band of UWB. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with compact overall size of 36 mm × 36 mm × 1.6 mm achieves good impedance matching, constant gain, and stable radiation patterns over an operating bandwidth of 2.38–12.40 GHz (10.02 GHz). © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:127–131, 2014

Highly Selective Differential-Mode Wideband Bandpass Filter for UWB Application

A novel highly selective wideband differential-mode bandpass filter (BPF) with good common-mode suppression is proposed on microstrip line for ultra-wideband (UWB) application. The initial BPF is similar to a two-stage branch-line structure in geometry and its improved one is formed by stretching the two vertical arms on the input and output ports from λg /4 to 3 λg /4. The aim is to achieve better filter selectivity by adding two additional transmission zeros from the extended arms. In our design, a symmetrical filter with two pairs of external ports is firstly decomposed into two bisections with two single ports under differential- and common- mode excitations. Our study shows that the two-port bisection circuits achieve bandpass and bandstop filtering performances under the differential- and common-mode operation in the lower UWB band, i.e., 3.1-5.1 GHz. The wideband differential-mode BPF is then designed and fabricated. All the three sets of results from the simulations based on the circuit model, fullwave software, and actual measurement are found in good agreement with one another. A highly selective differential-mode passband is achieved in the frequency range of 2.8-5.3 GHz, with a common-mode suppression of about 20 dB.

Transmission Performance of an In-Body to Off-Body UWB Communication Link

The objective of this study is to investigate the feasibility of an ultra wideband (UWB) impulse radio system for in-body to off-body wireless communication for biomedical applications. At first, a UWB antenna is designed in the UWB low band for implant use in the chest. Then the channel model is extracted and established based on the finite difference time domain (FDTD) simulation with an anatomical human body model. The established channel model consists of a small set of parameters for generating discrete time impulse responses. The generated model shows good agreement with the FDTD-calculated result in terms of key communication metrics. For effective communication over the multipath-affected channel, the pulse position modulation is employed and a 2-finger RAKE structure with a constant temporal delay is proposed in the receiver. The bit error rate performance has shown the validity of the system in the in-body to off-body chest channel.

An integrated CMOS low‐power UWB transmitter

AbstractIn this article, a fully integrated monocycle pulse‐based ultrawideband (UWB) transmitter is presented. Fabricated in a 0.18‐μm CMOS process, a low‐power all‐digital UWB pulse generator and modulator is proposed. The modulated pulse is further shaped by a driver amplifier. The transmitted pulses are binary phase modulated and meet the FCC UWB low frequency band (3.1–4.5 GHz) spectral mask specification. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1431–1436, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24376

A Tapered Slot Antenna with Flat and High Gain for Ultra-Wideband Applications

An elliptically tapered slot antenna (TSA) with high and relatively-flat gain is proposed in this paper. Its measured 10-dB impedance bandwidth is 2.65–12.90 GHz which covers the frequency range of ultra-wideband (UWB). Meanwhile, on the lower band of UWB (3 to 5 GHz), the measured antenna gain varies within 9.25 to 10.25 dBi. Furthermore, differing from many TSAs, the ground plane is just a simple rectangular structure but not a tapering shape.

Ultrawideband Suspended Plate Antenna With Enhanced Impedance and Radiation Performance

We describe an ultrawideband (UWB) suspended plate antenna (SPA) with enhanced impedance and radiation performance. This antenna consists of two layers. The bottom plate is suspended above a ground plane and fed by a tapered down feeding strip. The top layer consists of four identical radiating plates, each connected to the bottom plate by a vertical strip. The design is optimized numerically and validated experimentally. The measured results show that the antenna achieves an enhanced impedance bandwidth of 72.7% (2.8-6.0 GHz) for VSWR les 2 with stable radiation performance in terms of gain from 8.0-9.9 dBi, direction of maximum radiation, and high copolarization-to-cross-polarization ratio of ges 12 dB across the lower UWB band of 3.1-4.8 GHz.

Low-cost small-size tapered slot antenna for lower band UWB applications

A low-cost small-size tapered slot antenna (TSA) is investigated in view of ultra-wideband (UWB) applications. First, the bandwidth of the antenna is studied for the lower UWB band: 3.1-4.85 GHz. Secondly, the design is made as small as possible. Thirdly, the pulse distortion of a modulated Gaussian pulse in the lower UWB band, between 3.5 and 4.5 GHz, is investigated based on the measured S/sub 21/-parameter. The low distortion observed indicates that this TSA is suitable for applications in the lower UWB band.