Content uploaded by Patrick McEvoy
Author content
All content in this area was uploaded by Patrick McEvoy
Content may be subject to copyright.
A preview of the PDF is not available
Performance evaluation of antennas for UWB radar and positioning systems
Abstract and Figures
This paper presents a study of the performance of three antennas for ultra wideband radio ranging systems. By using different pulse types, the performance of the antennas is measured and quantified by using the Fidelity Factor.
Figures - uploaded by Patrick McEvoy
Author content
All figure content in this area was uploaded by Patrick McEvoy
Content may be subject to copyright.
... The system uses a linear array of antennas oriented to aim at the ground in front of the vehicle. The primary application of this radar system is groundpenetration imaging to detect buried objects, specifically improvised explosive devices (IEDs) [4]. From an antenna design perspective, the important term here is "improvised"; these devices can be almost any shape and size. ...
... By designing for an antenna cutoff frequency below the radiated pulse's cutoff, high n spirals should provide a constant group delay over the frequency band of interest. [1,2,4,6]. Turn #1 of each spiral widens as n increases, introducing high frequency axial ratio degradation. ...
Radar systems that allow early detection of underground IEDs can save lives. The Microwave Impulse Radar (MIR) capable of IED detection requires antennas capable of transmitting sub-nanosecond pulses over ultra-wideband (UWB) frequency ranges. This thesis investigates the suitability of a novel MIR antenna for high-accuracy ground-penetrating radar (GPR) applications. Key GPR antenna considerations are pulse dispersion, size, and cost. UWB horn antennas provide excellent dispersion performance but limit system efficacy due to significant size and cost requirements. Micro-strip spiral antennas provide a low-cost alternative to UWB horn antennas, but common spiral designs demonstrate poor pulse dispersion performance. The article “Low-Dispersion Spiral Antennas” proposes using combination spirals, which combine the performance of multiple simple spiral antennas. This work investigates combination spiral suitability through 3D EM simulations and micro-strip fabrication. Testing results indicate that combination spirals possess improved pulse fidelity versus current spiral designs. Size and cost improvements are realized over horn antenna solutions. Updated simulation hardware and fabrication equipment could allow future combination spiral antennas to rival horn antenna performance.
... The FS simulation of the fidelity factor was performed by placing farfield probes at a distance of 10 cm from the proposed antenna. Fidelity is evaluated by determining the peak of the cross correlation between the port and the probe signal [24]. The probes are placed by varying θ in a fixed step of 20°in the xz plane (φ = 0°) and yz plane (φ = 90°). ...
The paper presents the design and investigation of a flexible all-textile antenna operating in the Wireless Body Area Network (WBAN) Ultra Wideband (UWB) specified by IEEE 802.15.6 standard. The proposed antenna features an innovative and compact UWB radiator on top of the overall structure with a full ground plane on its reverse side. The radiator, which is based on a microstrip patch combined with multiple miniaturization and broad banding methods resulted in a simple topology and a compact size of 39 mm x 42 mm x 3.34 mm (0.51 x 0.55 x 0.043 λ). In comparison to literature, the proposed structure is considered to be the most compact microstrip-based textile UWB antenna to date featuring a full ground plane. The choice of the commercial textiles is also made based on cost efficiency, ease of accessibility and ease of fabrication using simple tools. Meanwhile, the full ground plane enables the antenna operation in the vicinity of the human body with minimal body coupling and radiation towards it, ensuring operational safety. Besides its operation in the mandatory channel of WBAN-UWB low and high band, the proposed antenna also operates and preserves its performance in five other optional channels of high band when placed on body and under bend condition of 30⁰ and 60⁰. The proposed antenna successfully achieved the specific absorption rate below the regulated limit specified by Federal Communications Commission.
... In each of the planes these probes were placed every 20° at 10 cm from the ATA-FGP. The fidelity is computed by determining the absolute max or peak value of the cross-correlation function of the signals [35]. This was done using the default Gaussian pulse and the template based post processing in CST MWS. ...
A fully textile microstrip topology with Ultra Wideband (UWB) characteristics useful in Wireless Body Area Networks (WBAN) is proposed. The antenna is operable within the full UWB band and incorporates a full textile shielding ground plane. The full ground plane is shown to be crucial in maintaining the performance when worn on-body. It successfully reduces any on-body performance degradation, resulting in a very robust structure. A detailed numerical and experimental evaluation of the antenna is performed in free space and on body. Index Terms—Ultra wideband (UWB) antennas, conformal antennas, directive antennas, Wireless Body Area Network (WBAN).
A design overview for a microstrip antenna topology operating within the full UWB band is described. Existing broadbanding concepts have been creatively combined throughout this design to enable the UWB behavior, while simultaneously keeping the full ground plane intact. This is crucial in maintaining worn antenna performance. It successfully reduces any on-body performance degradation, resulting in a very robust structure. A detailed numerical and experimental evaluation of the antenna is performed in free space and on body.
An efficient multiobjective evolutionary algorithm is described for optimizing a novel spline based printed monopole antenna. The antenna geometry is based on spline outlines. Both radiating element and groundplane are simultaneously optimized by the algorithm. The resulting antenna performance is evaluated. It is shown that the evolutionary algorithm and the spline geometry can be used to efficiently generate ultrawideband antennas on limited computing resources.
Ultrawideband (UWB) signaling is a modern wireless technique that reuses previously allocated RF bands by spreading the energy thinly in a wide spectrum, thus rendering signals imperceptible in the noise floor of conventional narrowband receivers. There are several methods of generating and radiating UWB signals, including a low-duty-cycle UWB implemented as time-modulated UWB (TM-UWB), and a high-duty-cycle direct-sequence phase-coded UWB (DS-UWB). Even conventional radio techniques such as orthogonal frequency-division multiplexing (OFDM) have been proposed, based on the “loose” spectrum access rules of the U.S. FCC Report and Order, which legalizes the emissions. Unique ways of coding and positioning the impulses, as in transmitted-reference delay hopped UWB (TRD-UWB), can result in the extremely simple UWB radio architectures. Here, the technological basics and performance of time-position-coded impulse UWB, the direct-sequence-coded UWB, and the transmitted-reference UWB approaches are compared with conventional radio approaches. Several UWB approaches have been proposed in the IEEE 802 standards arena. Applications of UWB devices are presented and potential uses of UWB are described. Short-pulse, low-power techniques have enabled practical through-the-wall radars, centimeter precision 3D positioning, and communications capabilities at the high data rates, all with exceptional spatial capacities.
A novel Bezier spline-based geometry for printed monopole antennas is presented. Quadratic curves are used to describe the outline of the radiating element. The geometry is optimised by a genetic algorithm. A small number of control points are used to define the geometry, ensuring a small search space for the GA. The resulting antenna has an impedance bandwidth from 1.44 to 14.7 GHz
Frequency-domain concepts and terminology are commonly used to describe antennas. These are very satisfactory for a CW or narrowband application. However, their validity is questionable for an instantaneous wideband excitation. Time-domain and/or wideband analyses can provide more insight and more effective terminology. Two approaches for this time-domain analysis have been described. The more complete one uses the transfer function, a function which describes the amplitude and phase of the response over the entire frequency spectrum. While this is useful for evaluating the overall response of a system, it may not be practical when trying to characterize an antenna's performance, and trying to compare it with that of other antennas. A more convenient and descriptive approach uses time-domain parameters, such as efficiency, energy pattern, receiving area, etc., with the constraint that the reference or excitation signal is known. The utility of both approaches, for describing the time-domain performance, was demonstrated for antennas which are both small and large, in comparison to the length of the reference signal. The approaches have also been used for other antennas, such as arrays, where they also could be applied to measure the effects of mutual impedance, for a wide-bandwidth signal. The time-domain ground-plane antenna range, on which these measurements were made, is suitable for symmetric antennas. However, the approach can be readily adapted to asymmetric antennas, without a ground plane, by using suitable reference antennas.< >
A novel optimization procedure for the design of antennas for ultrawideband (UWB) wireless communication systems is presented. The optimization is based on the time-domain characteristics of the antenna. The optimization procedure was applied to a simplified version of the volcano smoke antenna proposed by Kraus. However, any other type of UWB antenna can be treated with the same technique. Our optimization procedure aims at finding an antenna not only with low VSWR but also a low-dispersion one which will ensure high correlation between the time-domain transmitting antenna input signal and the receiving antenna output signal. In pulse communications systems, usually an input signal form suited to a particular purpose is used. Hence, we strive to design the best antenna for a given input signal form. The optimization technique adopted here makes use of genetic algorithm (GA) search concepts. The electromagnetic analysis of the antenna is done by means of a finite-difference time-domain method using the commercially available CST Microwave Studio software
The Commissions of the European CommunitiesEC Commission Decision of 21 February 2007 on allowing the use of the radio spectrum for equipment using ultra-wideband technology in a harmonised manner in the Community Ultra Wideband Radio Technology
[1]
Federal Communication Commission, Part
15, First Report and Order, May 2002.
[2]
The Commissions of the European
Communities, " 2007/131/EC Commission
Decision of 21 February 2007 on allowing
the use of the radio spectrum for equipment
using ultra-wideband technology in a
harmonised manner in the Community ",
Official Journal of the European Union, vol.
50, L 55, pp.33-36, February 2007
[3]
IEEE Computer Society, 802.15.3 Part 15.3:
Wireless Medium Access Control, (MAC)
and Physical Layer (PHY), Specifications
for High Rate Wireless and Personal Area
Networks (WPANs), The Institute of
Electrical and Electronics Engineers, 29
September 2003.
[4]
IEEE Computer Society, Part 15.4: Wireless
Medium Access Control (MAC) and
Physical Layer (PHY) Specifications for
Low-Rate Wireless Personal Area Networks
(WPANs), The Institute of Electrical and
Electronics Engineers, 31 August 2007.
[5]
K. Siwiak & D. McKeown, (2004). Ultra
Wideband Radio Technology. Chichester:
John Wiley & Sons Ltd.
[6]
2007/131/EC Commission Decision of 21 February 2007 on allowing the use of the radio spectrum for equipment using ultra-wideband technology in a harmonised manner in the Community
The Commissions of the European
Communities, "2007/131/EC Commission
Decision of 21 February 2007 on allowing
the use of the radio spectrum for equipment
using ultra-wideband technology in a
harmonised manner in the Community",
Official Journal of the European Union, vol.
50, L 55, pp.33-36, February 2007
4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs)
IEEE Computer Society, Part 15.4: Wireless
Medium Access Control (MAC) and
Physical Layer (PHY) Specifications for
Low-Rate Wireless Personal Area Networks
(WPANs), The Institute of Electrical and
Electronics Engineers, 31 August 2007.