massachusetts institute of technology...spiral slot patch antenna and circular disc monopole antenna...
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Spiral Slot Patch Antenna and Circular Disc Monopole Antenna for 3.1-10.6 GHz Ultra Wideband
Johnna PowellAnantha Chandrakasan
Massachusetts Institute of TechnologyMicrosystems Technology Laboratory (MTL)anantha, [email protected]
ISAP 2004August 18, 2004
Outline and Goals
IntroductionSpecifications and ConsiderationsDiscrete System ImplementationAntenna DesignsAntenna Results
FrequencyTime DomainAnechoic Chamber
IntroductionMotivation for UWB?
Revolutionary approach to wireless communicationPulse based waveforms compressed in time3.1-10.6 GHz, -41.3 dBm/MHzLow power levels allow for coexistence
Frequency
Time
UWB Impact on Antenna Design
Impedance Matching RequirementsBandwidth +100% of fc
|Γ|=|S11| < 1/3 VSWR < 2-10log|S11
2|= Return Loss > 10 dB
Wave ReceptionLinear PhaseHigh Radiation EfficiencyOmnidirectional Radiation PatternTime Domain Pulse Fidelity
Physical ConstraintsCompatible with Portable DevicesSmall, Compact, Planar
Power Loss < 10%
Discrete System Implementation
System Modeled after design by E. Green, Manny, B., “Ultra Wideband: A Disruptive RF Technology,” Intel Developer Conference, February 28, 2002.
Signal Generator
ImpulseGenerator
HPF
PowerAmp
WidebandAntenna
SwitchDriver
+-
RFSwitch
Splitter
PulseInverter
9.6”11”
HPF
Pulse Generator
LNA Splitter
Pulse Inverter
RF Switch
Switch Driver
Discrete System ImplementationTransmit Pulse Power Density
Power Spectrum vs. Frequency
FCC Spectral Mask
3.1 GHz 10.6 GHz
Frequency (GHz)
Discrete System Implementation
Transmit Pulse (red)Received Pulse (green)
Horn Antenna
Narrowband Monopole(Wire Antenna)
A wideband impedance match indicates optimal reception for a
wideband pulse
VSWR Wire
VSWR HornVSWR =2
Antenna Designs
Diamond DipoleElliptical Planar Antennas
CDMSpiral
Diamond Dipole
A B C
A
B
C
1.18 GHz
1.24 GHz
2.9 GHz
Time Domain Diamond Dipole
Single Ended and Differential Elliptical Antennas
30 0.24L
cf GHzL rλ∗
= =+
b
a
0.9”
1.5”
IC location
J. Powell and A. Chandrakasan, “Differential and Single ended Elliptical Antennas for 3.1-10.6 GHz Ultra Wideband”, AP-S 2004.
Circular Disc Monopole
Circular Disc Monopole1
1. Agrawall N. P. ,Kumar G.,Ray. K.P., “Wideband planar monopole antennas”, IEEE Transactions on Antennas and Propagation
VSWR =2
VSWR < 1.5 Power loss < 4%30 0.24
Lcf GHz
L rλ∗
= =+
2.3 cm
Spiral Equiangular Slot Patch
Equiangular Spiral Slot PatchVSWR=2
Antenna Feed
0.5 cm
Expansion rate = .38Total Arm Length = 6 cmOuter Radius = 2.25 cm
Designed in Remcom’s XFDTD
Back plane allows for use with PEDs
Fabricated with Omax waterjet and PCB milling router
VSWR and Group Delay
-6
-4
-2
0
2
4
6
8
10
3 4 5 6 7 8 9 10
Del
ay (n
s)
HornCDMSpiral
0
1
2
3
4
5
6
7
1 2 3 4 5 6 7 8 9 10
Horn
CDM
Spiral
VSWR vs. Frequency (GHz)
Group Delay vs. Frequency (GHz)VSWR=2
Pulse Fidelity Time Domain Plot
Rx Pulse- Red
Tx Pulse- green
500 ps/div
Taken from TDS 8000 Digitizing Oscilloscope
Antenna Results- Chamber
Spherical Coordinates:Azimuth = Rotation in φElevation = Rotation in θ
Photos courtesy Lincoln Labs
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
Antenna Results- Chamber
Lincoln Laboratory Measured Pattern: Azimuth =Blue, Elevation = Red
3.5 GHz
Spherical Coordinates:Azimuth = Rotation in φElevation = Rotation in θ
Gain vs. Frequency
-20-18-16-14-12-10
-8-6-4-20
3.5 4.5 5.5 6.5 7.5 8.5 9.5
-20-18-16-14-12-10
-8-6-4-20
3 4 5 6 7 8 9 10
Horizontal Polarization
Frequency (GHz)
Vertical Polarization
-40 -30 -20 -10 0 10
0
30
60
90
120
150-150
-120
-90
-60
-30
3.5 GHz 4 GHz 5 GHz
7 GHz 9 GHz 10 GHz
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
Radiation Patterns for Varying Frequency- Vertical Polarization
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
3.5 GHz 4 GHz 5 GHz
7 GHz 9 GHz 10 GHz
-40 -30 -20 -10 0 10
0
30
60
90
120
150-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
-40 -30 -20 -10 0 10
0
30
60
90
120
150
180
-150
-120
-90
-60
-30
Radiation Patterns for Varying Frequency- Horizontal Polarization
Summary
UWB Antenna DesignsVSWR < 2 for 3.1- 10.6 GHzPhysically Small SizeGood Pulse FidelityConsistent gain patterns
Discrete System ImplementationFuture Work: System Considerations