on-chip antenna element and array design for short range millimeter-wave communications

119 Pages·2007·1.57 MB·English

ON-CHIP ANTENNA ELEMENT AND ARRAY DESIGN
FOR SHORT RANGE MILLIMETER-WAVE
COMMUNICATIONS
DISSERTATION
Presented in Partial Fulfillment of the Requirements for
the Degree Doctor of Philosophy in the
Graduate School of The Ohio State University
By
Rudy M. Emrick, B.S. M.S.
* * * * *
The Ohio State University
2007
Dissertation Committee: Approved by
John L. Volakis, Adviser
Mohammed Ismail
Adviser
Chih-Chi Chen
Graduate Program in
Electrical and Computer
Robert Lee
Engineering
(cid:13)c Copyright by
Rudy M. Emrick
2007
ABSTRACT
Large amounts of worldwide unlicensed spectrum at 60 GHz is currently being
considered for high speed wireless solutions. However, a number of challenges remain
for this spectrum to be a viable solution for high volume consumer applications. In
this dissertation we look more closely at requirements for indoor antenna connectivity
with particular focus on the signal to noise ratio needed to overcome fading in multi-
path channels. A new analytical channel model, including multipath scattering, is
proposed and adapted to determine antenna requirements. These requirements are
then used to develop realistic signal to noise ratios for Silicon-based Radio Frequency
(RF) front ends. This dissertation considers three candidate antennas that show
promise for compact on-chip implementation. Given their small size and possible
losses at millimeter wave frequencies, we also focus on antenna efficiency for practical
metalizations on Silicon. Therefore, relevant material properties are examined to
determine the most accurate parameters to be used in the computational models.
It is concluded that arrays of the candidate antennas with spatial power combining
must be employed, but are still small enough for on-chip realization. The proposed
antenna array that meets performance requirements is as little as 7x7mm2, making it
about 1/3 of the target maximum size of 25x25mm2, required to enable integration
as part of a portable consumer devices.
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ACKNOWLEDGMENTS
ManythankstomywifeRitaandtwosons,SamandJosh. Withouttheirpatience,
understanding and assistance, my completion of this degree would not have been
possible. I would also like to thank my advisor John Volakis, who was extremely
helpful and understanding in my being a non-traditional student. I also greatly
appreciatethehelpofGeorgeSimpsonandBobNeidhardfromtheAirForceResearch
Lab for acquiring probes and taking the measurements which are included as part of
this work. In addition, I could not have succeeded without the generosity and solid
support from Motorola and my manager Vida Ilderem.
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VITA
1991 ........................................B.S. Electrical Engineering, Michigan
Technological University
1994 ........................................M.S.ElectricalEngineering,OhioState
University
2005-present ................................Graduate Student, Ohio State Univer-
sity
PUBLICATIONS
Research Publications
R.M. Emrick and J.L. Volakis “Antenna Requirements for Short Range High Speed
Wireless Systems Operating at Millimeter-Wave Frequencies.”. IEEE International
Microwave Symposium Digest, pp.974–977, 2006.
R.M. Emrick and J.L. Volakis “Millimeter-Wave and Terahertz Antennas”. Antenna
Engineering Handbook, McGraw-Hill, Chapter 23, 2007.
D. M. Ah Yo and R.M. Emrick “Frequency Bands for Military and Commercial
Applications.”. Antenna Engineering Handbook, McGraw-Hill, Chapter 2, 2007.
R.M. Emrick and J.L. Volakis “Inductively Loaded Millimeter-Wave Spiral Array on
Silicon.”. IEEE Antennas and Propagation Symposium, 2007.
FIELDS OF STUDY
Major Field: Electrical and Computer Engineering
Studies in Electromagentics: Prof. John L. Volakis
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TABLE OF CONTENTS
Page
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Vita . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Chapters:
1. Introduction to Millimeter-Wave and Terahertz Antennas . . . . . . . . . 1
1.1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 Wireless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.2 Radars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.3 Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Millimeter-wave Antennas . . . . . . . . . . . . . . . . . . . . . . . 7
1.2.1 Waveguide Antennas . . . . . . . . . . . . . . . . . . . . . . 8
1.3 On-Chip Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4 Submillimeter-wave and Terahertz Antennas . . . . . . . . . . . . . 23
1.5 Chapter Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2. Antenna Requirements for High Speed Wireless Systems Operating at
Millimeter-wave Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.2 Fading Multi-Path Channels . . . . . . . . . . . . . . . . . . . . . . 32
2.3 Effect of MIMO in Fading Multi-Path Channels . . . . . . . . . . . 34
2.4 Channel Model Within a Room . . . . . . . . . . . . . . . . . . . . 38
2.4.1 Analytical Model for a Room . . . . . . . . . . . . . . . . . 38
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2.4.2 SNR Calculations . . . . . . . . . . . . . . . . . . . . . . . 38
2.5 Chapter Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3. Material Properties of Gold and Silicon at High Frequencies and Their
Effect on Efficiency for Candidate Antenna Elements . . . . . . . . . . . 46
3.1 Initial Antenna Element Analysis . . . . . . . . . . . . . . . . . . . 46
3.2 Antenna elements used for this analysis . . . . . . . . . . . . . . . 57
3.3 Electrical Properties of Gold . . . . . . . . . . . . . . . . . . . . . . 62
3.4 Electrical Properties of Silicon . . . . . . . . . . . . . . . . . . . . . 73
3.4.1 Measured Results for the Spiral Element . . . . . . . . . . . 79
3.5 Material Property Effects on Efficiency . . . . . . . . . . . . . . . . 80
3.6 Chapter Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4. Antenna Array Implementation . . . . . . . . . . . . . . . . . . . . . . . 85
4.1 overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.2 Array Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4.3 The Array Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.4 Array and System Performance . . . . . . . . . . . . . . . . . . . . 89
4.5 Chapter Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.5.1 Design Guidelines . . . . . . . . . . . . . . . . . . . . . . . 97
5. Conclusions and Summary of Contributions . . . . . . . . . . . . . . . . 100
5.1 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . 100
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
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LIST OF FIGURES
Figure Page
1.1 Millimeter-wave (MMW) spectrum and applications. Bands shown are
unlicensed 60 GHz, easily licensed 70 and 80 GHz, 77 GHz automotive
radar, unlicened 90 GHz and emerging bands above 100 GHz. . . . . 3
1.2 Signal-to-noise (S/N) ratio at the receiver as a function of separation
distancebetweenthetransmitterandreceiver. Anantennawith20-dBi
gain was assumed (the horizontal lines show the required S/N ratios
for the indicated data rates and configuration) (after R. M. Emrick
and J. L. Volakis [3] IEEE 2006). . . . . . . . . . . . . . . . . . . . . 6
1.3 Automotive sensors for advanced safety systems . . . . . . . . . . . . 7
1.4 Hornantennas,connectedtoaWR15waveguide,operatingatmillimeter-
wave frequencies. The horn antenna on the left is precision assembled
whereas the horn on the right is cast and plated for lower cost. . . . . 10
1.5 Parallel plate slot array to improve manufacturability. Dielectric con-
stant of the employed material is 2.17 and an efficiency of 29 percent
was achieved (after J. Hirokawa and M. Ando [7] IEEE 1998) . . . . 11
1.6 Waveguide to microstrip antenna coupling using an aperture at the
broadwall to feed the microstrip antenna (after D. Pozar [8] IEEE 1996) 11
1.7 DoubleslotantennaimplementedonanLTCCpackage(afterK.Maruhashi
et al [9] IEEE 2000) . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.8 A multilayer parasitic microstrip antenna array implemented using
LTCC (after T. Seki et al [10] IEEE 2005). Measured absolute gain
for this antenna is 7.17 dBi. . . . . . . . . . . . . . . . . . . . . . . . 13
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1.9 Comparison of Substrate Properties for LTCC, FR4, and LCP. Data
is shown at 1 MHz for LTCC and 20 GHz for LTCC and LCP. . . . . 14
1.10 High-gainantennautilizingmultipleLCPlayerstoformaverticalarray
of spirals over a ground plane. The achieved gain is 12.3 dBi with a top
surface occupying 1.2 mm, and computations were carried out using
the Remcom XFDTD (after R. M. Emrick and J. L. Volakis [3] IEEE
2006). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.11 Transmission line losses in dB/mm using thin dielectrics. The SiO
2
substrate thickness 3 µm is representative when implementing 50 ohm
transmissionlinesinthetoplayersofsiliconwaferprocesses. Lossesfor
thicker GaAs substrates are also shown for comparison (use of higher
dielectric constants produce similar effects). . . . . . . . . . . . . . . 17
1.12 Approach for reducing losses by increasing the air volume near the
structure or components of interest (after C. Nguyen et al [12] IEEE
1998). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.13 Two-dimensional array utilizing membranes and air cavities to reduce
losses (after G. Rebeiz et al [14] IEEE 1990) . . . . . . . . . . . . . . 19
1.14 Formation of surface wave and other substrate modes can effect per-
formance of on-chip antennas (after N. Alexopoulos et al [15] IEEE
1983) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.15 Example layout of an edge-fed element on silicon for compact on-chip
antennas. When minimized in size, the antenna element measures only
360 mm 135 mm delivering 3.2-dBi gain and a 3-dB bandwidth of 17%. 21
1.16 Example of a millimeter wave antenna comprised of a half-circle el-
ement with a tuning slot. When the size is minimized, the element
measures 480 mm 240 mm delivering a gain of 3.8 dBi with a 3-dB
bandwidth of 17%. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
1.17 Example antenna on a thin membrane integrated with a detector op-
erating up to 700 GHz (G. Rebeiz et al [13] IEEE 1987). . . . . . . . 24
1.18 Log-periodic antenna element with a lens coupled to a hot-electron
bolometer for operation at 1-6 THz (after A. Semenov et al [17] IEEE
2007) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
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1.19 Micromachinedwaveguideantennafor1.6-THzoperation(afterJ.Bowen
et al [18] IEEE 2006). A gain of about 13 dBi was achieved. . . . . . 26
1.20 Photoconductive antenna to generate and transmit or receive THz sig-
nals (L is antenna length) . . . . . . . . . . . . . . . . . . . . . . . . 27
2.1 Wireless Standards Snapshot. . . . . . . . . . . . . . . . . . . . . . . 30
2.2 Worldwide Spectrum Available at 60 GHz. 3 GHz of common world-
wide spectrum exists from 59-62 GHz, as highlighted. . . . . . . . . . 31
2.3 Bit Error Rate as a function of γ for a single input single output
b
system. Bit error rates for K=0, 6 and 12 for BFSK and BPSK are
shown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.4 MIMO implementation using t transmit and r receive antennas . . . . 36
2.5 Bit Error Rate as a function of the average SNR per bit for a 2x2
MIMO system having L = t·r = 4 MIMO channels (SISO is shown for
comparison). Bit error rates for K=0, 6 and 12 with BPSK are shown. 37
2.6 Multipath delay profile for transmit and receive separation of 5m, 15m
and 35m which is described by Equation 2.5 at 60 GHz . . . . . . . . 39
2.7 SNR at the receiver as a function of transmit and receive antenna
separation with antenna gain of 6dBi assumed for both transmit and
receive. Required SNR levels are shown for various conditions at 60 GHz 41
2.8 SNR at the receiver as a function of transmit and receive antenna
separation with antenna gain of 20dBi assumed for both transmit and
receive. Required SNR levels are shown for various conditions at 60 GHz 42
3.1 Mineaturized spiral elements included in this analysis using a) straight
arms and b) square meander-line inductive loading . . . . . . . . . . 47
3.2 Example layout of antenna approach using LTCC to implement wide-
band triangle and Yagi antennas for ”Antenna in Package” approach
from [38]. Exploded layout view (a, wideband triangle b) and Yagi c)
layouts are shown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
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