S. M. R. Jones

Probability Distribution of Rician K-Factor in Urban, Suburban and Rural Areas Using Real World Captured Data

The Rician K-factor of the vehicle-to-vehicle (V2V) wireless propagation channel is estimated using a moment-based method on the envelope of measured pulse data. The measurements were carried out under vehicle-to-vehicle wireless communication channel condition with car rooftop antenna heights at one end of the link and very low antenna height at the other end. Data captured from typical urban, suburban and rural areas are analyzed and the K-factor probability density function is generated for each scenario to give an insight into the V2V channel behavior. For all three areas, the majority of K values are found to be within the range of -10 to +10 dB. The K-factor distributions are close to normal with mean values of 1.8, 2.6 and 3 dB respectively for urban, suburban and rural area.

Evidence for the presence of turbulent attenuation on low-elevation angle Earth-space paths. 2. Frequency scaling of scintillation intensity on a 10/spl deg/ path

For pt.1 see ibid., vol.45, no.1, p.73-84 (1997). This paper presents the results of and conclusions drawn from two experimental studies of low-elevation, slant-path scintillation. Part I related to 11.2-GHz measurements at an elevation angle of 3.3/spl deg/. Part II describes 14- and 11-GHz observations made on a (nominal) 10/spl deg/ path over a four year period. The resulting time-series data have enabled frequency scaling to be investigated in some depth. Scintillation occurring during periods unassociated with fading is found to be well modeled in its frequency scaling behavior by classical theories of clear air turbulence (CAT). This is not the case, however, for scintillation that occurs during, just before, or just after rain-induced fading. A rapidly fluctuating attenuation mechanism, not separable from CAT-induced scintillation on the basis of its spectrum alone, is thought to be responsible for this anomalous frequency-scaling result.

Wavelet Packet Transform Modulation for Multiple Input Multiple Output Applications

into the wavelet packet transform (WPT) modulation scheme for Multiple Input Multiple Output (MIMO) band-limited systems is presented. The implementation involves using the WPT as the base multiplexing technology at baseband, instead of the traditional Fast Fourier Transform (FFT) common in Orthogonal Frequency Division Multiplexing (OFDM) systems. An investigation for a WPT-MIMO multicarrier system, using the Alamouti diversity technique, is presented. Results are consistent with those in the original Alamouti work. The scheme is then implemented for WPT-MIMO and FFT- MIMO cases with extended receiver diversity, namely 2 ×Nr MIMO systems, where Nr is the number of receiver elements. It is found that the diversity gain decreases with increasing receiver diversity and that WPT-MIMO systems can be more advantageous than FFT-based MIMO-OFDM systems.

Folded Loop Balanced Coplanar Antenna for WLAN Applications

A novel balanced rectangular loop antenna is proposed, having an ungrounded coplanar waveguide (CPW) feed configuration and a folded structure at both ends. This antenna is designed for operation over the 2.4 GHz and 5 GHz WLAN frequency bands. Bond-wire bridges are used along the CPW feed line to ensure the same potential across the CPW ground planes. The self-balancing structure that can be realized in a loop antenna offers operation without the need of a separate balun for connection to a RF source. A prototype of the optimized antenna with overall dimension of 31 mm × 16 mm × 3 mm was fabricated and tested. The calculated and measured results show good agreement, confirming good wideband characteristics with multiband operation. An example application of the proposed antenna is studied when used in handheld devices. The results show that this antenna has performance largely independent of perturbations of its associated ground plane, because the balanced feed created by the intrinsic balun structure minimizes ground plane currents.

New approach for designing beam steering uniform antenna arrays using Genetic Algorithms

A new approach to the design of electronic beam steering in antenna arrays is introduced and analysed. The technique is demonstrated for a uniform antenna array structure. The radiation pattern of the antenna array is formed and the beam steering tuned using the Genetic Algorithm. The results show a reasonably wide steering angle with acceptable experimentally-measured return loss. A simple mathematical formula is developed to highlight the operation of this linear array.

Design and analysis of UC-EBG on mutual coupling reduction

A new Uniplanar Compact Electromagnetic Bandgap (UC-EBG) structure is proposed in order to achieve a smaller unit cell operating at lower frequency stop band. Its design is detailed and an experimental result is presented. The property of the proposed UC-EBG is compared with the distorted uniplanar compact EBG (DUC-EBG). The application of the proposed UC-EBG is examined. A parametric study on various thicknesses of dielectric substrate is also discussed.

Experimental throughput analysis and MIMO indoor propagation prediction for 802.11n system

Significant improvements in the quality and reliability of indoor WLAN connections are claimed for devices with MIMO technology using the recently developed standard 802.11n, which allows users to achieve theoretically up to 300-600 Mbps on a single transmission. This paper presents an analysis of a commercial 802.11n MIMO 2×3 dual band (2.4 & 5 GHz) system focusing on the operational throughput performance over an indoor environment with Line of Sight and Non Line of Sight scenarios. Although many authors have provided evidence on the effectiveness of this technology in field strength distribution, throughput or propagation-simulation environments, efforts on all parameters combined is limited. This paper also intends to elucidate the comparison of these metrics by evaluating a MIMO 2×3 dual band (2.4 & 5 GHz) system, focusing on physical measurements of the operational performance, in comparison with simulations of the field strength distribution over an indoor environment.

Design studies of ultra-wideband microstrip antenna for ultra-wideband communication

This paper presents a circular printed monopole antenna for the Ultra-Wideband (UWB) applications. The antenna achieved over all bandwidth of 120% from operating frequency from 3.1 to 11.5 GHz for return loss <-10dB. The parameters of the antenna which affect the performance of the antenna are investigated. The computed and experimental results of the return loss and radiation patterns are in good agreement. These results evident that the proposed antenna can yield an ultra-wide impedance bandwidth with a good radiation patterns over the required operating band. Thus, these features make this antenna suitable to be used in wireless ultra-wideband communication.

A compact size reconfigurable PIFA antenna for use in mobile handset

A planar inverted-F type reconfigurable antenna with slot is presented. The antenna can cover frequency bands which include Digital Cellular Service (DCS: 1710–1880 MHz), Personal Communication Service (PCS: 1850–1990 MHz), and Universal Mobile Telecommunications System (UMTS: 1900–2200 MHz). Initially, the reconfigurability of the proposed antenna is achieved by attaching lumped capacitor over the slit of the radiator with values range from 1.5–4pf. The measured and simulated results reveal that the fabricated proposed antenna is capable of obtaining tunable frequency ratio from 1850MHz to 2200MHz with overall size of 21×13.5×5 mm3 that makes it suitable for handset applications and can be easily integrated inside commercial mobile handsets.

Reconfigurable antenna design approach for mobile applications and a technique for harmonics suppression

A design procedure for reconfigurable mobile antenna module is presented. A tuneable antenna, including a varactor diode placed at specific position over the radiating slot, was fabricated and tested over several targeted frequency bands (centred at 1.7, 1.8, 1.9 and 2.04 GHz) and their harmonics. A limitation of the tuneable antenna is its non-linear behaviour at the transmitter. A method to measure the radiated power from an active antenna (AA) at fundamental and harmonic frequencies is introduced to suppress the harmonic radiations of the active antenna. The experimental results on the received power show a very good capability for harmonic suppression.