Research on the Electromagnetic
Interface of Wireless Systems
18th November, 2004
CWSA Wireless Workshop
William J. Chappell,
Electrical and Computer Engineering Dept, Purdue University, West Lafayette, IN
Applied Electromagnetics at Purdue
•Our Concept for Future High Frequency Circuits
•Current State of the Art for Commercial High
Frequency Receivers
•Active Research Topics in Applied Electromagnetics
• DARPA TEAMS – Vertical Packaging of Mixed Signal Systems
• DARPA Metamaterials – Composite Materials
• 21st Century – High Frequency Advanced Substrates
• NSF – RF Diversity for Sensor Networks
• Dupont/Invista – Electrotextiles for High Frequency Antennas
• Nexaura Systems– Z-axis Epoxy for High Density Interconnects
•Conclusions on Status of the Field of Applied
Electromagnetics
Goals for our Research
•Goal is to Establish Purdue as a Major Player
in the Fields of Advanced Packaging and High
Frequency System Integration
Our “Concept Car”
Vision of Future
Microwave Systems
Both heterogeneous
materials and
multidimensional
electromagnetic designs
must be understood
Comparison with Commercial State of the Art
Commercial Example of a High Frequency Circuit
MaCom 24 GHz Pulsed Rear Looking Radar
Comparison with Commercial State of the Art
Commercial Example of a High Frequency Circuit
MaCom 24 GHz Pulsed Rear Looking Radar
DARPA TEAMS
Vertically Integrated Mixed Signal Circuits
DARPA TEAMS
Vertically Integrated Mixed Signal Circuits
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Q~20
IC – Active Substrate
Q~200
High-Q Components Layer
High–Q Elements Embedded in A
Low Loss Substrate
Unlike Transistors - Passive Components
are Not Better When They are Smaller
Si InterPoser
High Density, Low to Medium Q
Components, Interconnects, and
Distribution
Q~1,000
High-Q Layer –
Larger, Ceramic Elements – Fewer
Interconnects, More Volume
Truly Three-dimensional Packaging Through
Multilayer Polymer Processing
Monopole
“Sliced” CAD model
(50 µm/layer)
Embedded
Cavity
# 354-401
# 334-353
# 325-333
Coax feed
# 319-324
# 285-318
# 248-284
# 201-247
Vertically integrated monopole with a
cavity resonator
 Layer-by-layer monolithic processing,
high aspect ratio
 Fast & maskless, >20 different 2D
layouts, >400 layers are possible

# 001-200 (Layer #)
Truly Three-dimensional Packaging Through
Multilayer Polymer Processing
Monopole
Embedded
Cavity
Layer 354-401
(a)
Layer 334-353
Coax Feed
Layer 325-333
Layer 319-324
Example Two-pole Filter
(b)
Layer 285-318
Layer 248-284
Layer 201-247
Layer 1-200
(c)
Monolithic Three–Dimensional Package
with Integrated Helix Antenna and
Filtering
Vertically Integrated Filter Using SL1
0
S21 (dB)
-1
-2
-3
Meas.
-4
Simu.
-5
19.4
19.6
19.8
20
0
20
-10
10
-20
0
-30
-10
-40
-20
Meas.
-50
-30
Simu.
-60
-40
17
18
19
20
21
Frequnecy (GHz)
22
23
BW = 2%, IL = 0.27dB @ K Band
Return Loss (dB)
Insertion Loss (dB)
Frequnecy (GHz)
• Q>2,000
• Footprint < λ2
• Vertical Integration Capability
Field Plot of Vertical Filter
Three dimensional
solutions allow for
previously
unobtainable designs
Full Wave
Simulations
Using Ansoft
HFSS
Integrated Vertical Packaging for RFICs
RFIC
DARPA Metamaterials
Composite Materials for Electromagnetic
Properties Not Found in Nature
Periodic/ Artificial Substrates for High
Frequency
Periodicity Creates
Effective Medium
Constructive and
deconstructive reflections
within periodic material
Frequency
Basic Principles of Periodic Materials
Kx = 0
Ky = 0
Kx = /t
Ky = 0
Kx = /t Kx = 0
Ky = /t Ky = 0
Composite Materials for High-Frequency Filters
Improving material properties through embedded periodicity
Typical Dispersion Diagram of Composite Materials
Frequency
i. Bandgap MacroPeriodicity
Periodic inclusions on the
order of a /4 to create
bandgap
i. Bandgap
ii. Mesoscale Periodicity
iii. Microscale Periodicity
Kx = /t
Ky = 0
Kx = 0
Ky = 0
ii. Mesoscale Periodicity
Kx = /t
Ky = /t
Kx = 0
Ky = 0
Periodicity on the order
Propagation vector
of a /10 to create
effective medium
inside of a cavity
For what reason?
0
20
-10
10
-20
0
-30
-10
-40
-20
Meas.
Simu.
Example Filter
-30
I.L. 0.3 dB, BW 2.2%
-60
-40
17
18
19
20
21
Frequnecy (GHz)
22
23
Return Loss (dB)
Insertion Loss (dB)
Low insertion loss, narrow-band preselect filters
implying high-Q materials and resonators
-50
Periodic rods in host dielectric
creates multiple reflections
Internal patterning in
ceramic layers creates
synthesized dielectric
iii. Microscale Periodicity
Periodicity on the order
of /100 to create
effective medium and
anisotropic materials
Porosity creates ability to
have graded dielectrics
within a single substrate
MADL (K-Band Satellite Communication) Block Diagram
ALC
1
DRO 1
Diplexer
Ref. DRO 2
IF/A
BFN
...
DRO n
48
Down Converter
Control/B
Power
T/R Electronics
Device
Driver
IF/B
Control/A
Device
Driver
Array
Antenna
Assembly
Controller
Power
Converter
Antenna
Interface
Unit
Filters
need to be
inserted
here
MADL Antenna Description

Phased Array Antenna
• Operating frequency: K–Band Size: ~3 inches diameter,
~2" deep

Intended to be installed in multiple locations on
aircraft to provide a wide field of view
Flight
Antenna Interface
Unit (AIU)
Lead
Antenna Array Assembly (AAA)
LOS
Flight
Lead
WB
SATCOM
Typical System is in LTCC
without Preselect Filter
• Filter with Q greater than 700 is needed
Filters need to be added to the
MCM as layers within an LTCC
package.
4-Element BGA MCM
Bandgap Filter Results

Extruded High-K Material in a
Polymer Host
• r = 90, Allows Wider Bandgap
• Electrically Smaller Filter than
Alumina


0.88 mm
E-field
H-field
I.L. = -1.1 dB for a 1 % filter
QUNLOADED ~ 1,100
0
-5
0
-10
20
-10
-15
10
-20
-20
0
19.7 19.9 20.1 20.3 20.5 20.7 20.9
-30
-10
-40
-20
-50
-30
-60
-40
18
19
20
21
22
23
24
“Wide Bandgap Composite EBG Substrates” AP Transactions - Special Session on
Metamaterials - Accepted for Publication in 2003.
New Indiana 21st Century Project
Advanced Packaging for High Frequency Receivers –
Commercialization of Next Generation of Satellite Radio
Delphi, Dupont, CTS, Nexaura Systems, and Omega Wireless
Vertical Packaging for Satellite Radio
Current Commercial Realizations of Automotive Receivers
Active Components
Numerous Picked and Spaced
Circuits
Discrete Components
Individual L and C
components
IC
Package Components
Strictly a Carrier
Intermediary Advanced Packaging Designs
Active Components
Separate IC’s
IC
IC
Package Components
Hybrid Integrated High-K
passive component bank
 Buried Integrated
Discrete Components
Ultimate Goal – Zero External
Passives
High-K
passives
Active Component
1 or 2 IC Circuits
Top Down
PA
Package Components
Completely Buried
Passive
Components
Sideview
Exploded View of
Bluetooth Example
Layered Circuit
Nexaura Z-axis Epoxy
•Unpatterned interconnects through
magnetically aligned Epoxy
Top Substrate
columns
No
•Conducts current in patterning
only one direction
Ideal
-10
Meas.
-20
0
S21 (dB) (dB)
Transmission
S11 (dB)(dB)
Reflection
0
-1
-2
-30
-3
-40
S11--measured
-50
-4
S11--simulated
S21--measured
S21--simulated
-60
0
2
4
-5
6
Freq. (GHz)
8
10
Bottom Substrate
NSF - Wireless Sensor Networks
Diversity Enabled Sensor Motes



Semi-Directional Antennas for Selection Diversity in
Sensor Network Nodes
Miniaturized Antennas Enabled Through
Incorporation of High Dielectric Constant Materials
Testbed is Being Established with Wireless Sensor
Boards

Each mote senses temperature, magnetic field, acoustics, light,
and acceleration
Cross-Layer Interaction
Fault
Tolerant
Middleware
Sensor Mote
Advanced Polymer and Ceramic
Processing
Diversity Enabled Packaged
Node
Efficient
Networking
Comparison of Diversity Schemes
Diversity Enabled Sensor Motes
802.11 Switched Polarization Diversity
Full Diversity Schemes
Diversity Schemes
Diversity Enabled Sensor Motes
SP4T
Sensor Mote Switched Angle Diversity
•Only hardware upgrade is a SP4T switch and multiple antenna
•Uses The RSSI indicator to compare channels
•One of the major problems is that motes are designed to work in free space.
Electrotextiles for High Frequency Antennas
Sponsored By Invista/ Dupont
Example Diversity
Embedded
Dipole
Diversity Enabled by
Multiple Antennas
•Radiation from
clothing enabled by
textile conductors
•Larger canvas for
antenna designer
Inner Surface
Shields
Outer Surface
Radiates
Inner Shield
Blocks Energy
Interaction with Wireless Center
•Developed an Electromagnetics Teaching
Laboratory
•Experimental based curriculum for both graduate and
undergraduate
•Development of packaging and system
integration capabilities
•LTCC and traditional packaging prototyping
•Interface wireless circuits with the Birck Nanotechnology
Center and microelectronics facilities
Conclusions

We are at a new age in high frequency circuits
• The 80’s and the 90’s are well known as the decades of
numerical solvers for three-dimensional electromagnetic
problems




The question is no longer how do we analyze
complex high frequency structures, but rather:
Why?
What are the applications that utilize these
advances?
How do we design utilizing these advances?
At Purdue, we are trying to answer these
questions with the correct combination of
theory, fabrication, design, and measurement.