Ultrawideband Antennas

by Valderas, Daniel; Sancho, Juan Ignacio; Puente, David; Ling, Cong; Chen, Xiaodong

• ISBN13: 9781848164918
• ISBN10: 1848164912
• Format: Hardcover
• Copyright: 2010-10-15
• Publisher: Imperial College Pr

Summary

Ultrawideband (UWB) technology, positioned as the cutting edge of research and development, paves the way to meet the emerging demands set by broadband wireless applications, such as high-speed data transmission, medical imaging, short-range radars, electromagnetic testing, etc. This breathtaking resource builds upon the basics of UWB technology to provide a complete compilation of figures of merit along with a vital state-of-the-art of the different antenna alternatives that are to be employed according to the specific application. Without excessive recourse to mathematics, this volume emphasizes on the UWB antenna design and equips readers with practical prediction techniques based on simple formulas and models. The big picture of UWB antenna technology would not be complete without addressing its applications, and this will serve to provide consultants with key clues for slot market searching. Containing over 150 supporting illustrations and figures, this comprehensive overview of UWB technology, antenna design and applications is a vital source of information and reference for R&D organizations, researchers, practitioners, consultants, RF professionals and communication engineers.

Table of Contents

Foreword	p. v
Acknowledgements	p. vii
Authors	p. ix
Introduction to Ultrawideband Systems	p. 1
Overview	p. 1
UWB Schemes	p. 3
Impulse radio/time hopping	p. 3
Direct sequence	p. 5
Frequency hopping	p. 6
OFDM	p. 9
Industry Standards	p. 11
Single band versus multiband	p. 11
Standards	p. 11
Applications	p. 12
Challenges	p. 13
Figures of Merit for UWB Antennas	p. 15
Requirements for a UWB Antenna	p. 16
Efficiency and matching	p. 16
Signal distortion and dispersion (ringing)	p. 17
Stability over frequency of the transmission-reception transfer function	p. 17
UWB Antenna Parameters	p. 19
Variability in the frequency domain	p. 19
Variability in the time domain: Pulse distortion parameters	p. 23
Variability in the space domain	p. 24
Simulation in the Time Domain	p. 27
Classification of UWB Antennas	p. 29
Helical Antennas	p. 29
Frequency-independent Antennas	p. 31
Spiral antennas	p. 31
Biconical antennas	p. 32
Log-periodic Antennas	p. 34
Horn Antennas	p. 36
3D horn antennas	p. 36
2D horn antennas	p. 38
UWB Antennas Derived from Resonant Antennas	p. 39
3D monopoles	p. 39
2D resonant antennas	p. 46
Conclusions	p. 47
UWB Monopole Antenna Analysis	p. 51
Introduction	p. 51
Current-conductive Parts on Planar Monopole Antennas	p. 51
Currents parallel and perpendicular to the ground plane: A working hypothesis	p. 51
Non-radiating currents in a PMA	p. 54
Transmission Line Model for UWB Monopole Antennas	p. 56
General description	p. 56
Description of the model	p. 58
Purpose of the analogy	p. 58
Graphical approach: The Smith Chart	p. 59
Design Based on TLM	p. 61
Design of an UWB-PMA antenna with a given bandwidth	p. 61
Design of an UWB-PMA antenna having a maximised bandwidth	p. 61
Design of omnidirectional UWB antennas	p. 62
Design of directional UWB antennas	p. 62
Design of 2D PCB antennas for UWB	p. 62
Case study 1: Semi-rectangular planar monopole case	p. 62
Case study 2: Broadband matching of a full-rectangular planar monopole case	p. 65
UWB Monopole Antenna Bandwidth Synthesis	p. 69
Introduction	p. 69
Defining the Lower Limit of the Frequency Band	p. 70
Obtaining the Upper Frequency with Staircase Profile in TLM	p. 71
One step in a PMA's profile according to TLM	p. 71
Two steps in a PMA's profile according to TLM	p. 74
Analytical estimate of the upper limit of the band for a rectangular staircase monopole	p. 75
Obtaining the Upper Frequency through Slot Etching	p. 78
Case Study 1	p. 82
Design	p. 82
Simulation and measurements	p. 83
Case Study 2	p. 86
Design	p. 86
Simulation and measurements	p. 87
Case Study 3	p. 88
Design	p. 89
Simulation and measurements	p. 90
Discussion: Impedance matching and transfer function	p. 92
UWB Monopole Antenna Bandwidth Maximisation	p. 95
Introduction	p. 95
Modifying the profile of the edge of the PMA closest to the ground plane	p. 97
Applying TLM: Changing the characteristic impedance	p. 97
Case Study: Maximising AMP Impedance Bandwidth	p. 101
Lower frequency limit of the band: Initial L, W and p parameters	p. 101
Adjusting the width	p. 102
Changing the height p over the ground plane	p. 102
Implementing a bevelled cut	p. 102
Changing the profile close to the feed	p. 105
Simulation and measurements	p. 106
Discussion of Spectral Efficiency in Broadband Antennas	p. 108
UWB Folded Monopole Antennas	p. 115
Introduction	p. 115
Current Distribution in an Antenna Folded along Vertical Axes	p. 117
TLM Applied to an FMA	p. 117
Case Study: Maximising FMA Impedance Bandwidth	p. 120
Design	p. 120
Simulation and measurements	p. 123
Design options	p. 133
Revolution Monopole Antennas	p. 139
Introduction	p. 139
Current distribution in an RMA	p. 140
TLM applied to an RMA	p. 143
Case study: Maximising RMA impedance bandwidth	p. 143
Printed Circuit Monopoles	p. 157
Introduction	p. 157
Current Distribution in a PCM	p. 158
TLM Applied to a PCM	p. 158
Case Study: Tailored Bandwidth for UWB PCM	p. 160
Design	p. 160
Simulations and measurements	p. 161
Applications of UWB Antennas	p. 167
UWB Communications	p. 167
Antennas required in impulse radio system	p. 168
Antennas required in MB-OFDM system	p. 171
EM Measurement	p. 173
EM spectrum monitoring	p. 173
EMC testing	p. 173
Medical Imaging - Breast Cancer Detection	p. 174
Horn and tapered slot antennas	p. 175
Stacked patch antennas	p. 176
Radars	p. 177
Antenna array in impulse radars	p. 178
Broadband phase array	p. 180
Bibliography	p. 183
Index	p. 191
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