Planar Diamond Antennas for UWB Radio Systems Xuan Hui Wu, Zhi Ning - - PowerPoint PPT Presentation

Planar Diamond Antennas for UWB Radio Systems

Xuan Hui Wu, Zhi Ning Chen, Ning Yang

http://www.geocities.com/xuanhui wu

Institute for Infocomm Research, Singapore National University of Singapore

APMC 2003, Seoul, Korea – p.1/17

Outline

About UWB wireless communications Research methods Measurement set-up & Results in FD&TD Single-band & multi-band schemes Selection of source pulse at a transmitter Emission level in free space Pulse detection at a receiver Conclusions

APMC 2003, Seoul, Korea – p.2/17

UWB wireless communications

Ultra-wide bandwidth of 3.1GHz - 10.6GHz, as regulated by FCC. Low power spectrum density, -41.3dBm/MHz. High data rate.

APMC 2003, Seoul, Korea – p.3/17

Methods

Both the TD and FD responses of the antenna system are studied. In simulation:

• 1. Adopt an FDTD algorithm of get the TD response.
• 2. Use Fourier Transform to extract the FD responses,

S11(ω) and S21(ω).

In measurement:

• 1. Obtain the S-Parameters by a Network analyzer

HP8510.

• 2. Use Inverse Fourier Transform to obtain TD

response.

APMC 2003, Seoul, Korea – p.4/17

Measurement set-up

APMC 2003, Seoul, Korea – p.5/17

S-Parameters

• 100
• 80
• 60
• 40
• 20

2 4 6 8 10 12 14 16 18 S-parameter (dB) Frequency (GHz) Measured S11 Simulated S11 Measured S21 Simulated S21

• 10dB bandwidth of |S11(ω)|: 6.8GHz - 15GHz
• 3dB bandwidth of |S21(ω)|: 5.0GHz - 14.6GHz

APMC 2003, Seoul, Korea – p.6/17

TD responses

• 0.02
• 0.015
• 0.01
• 0.005

0.005 0.01 0.015 0.02 0.025 0.8 1 1.2 1.4 1.6 1.8 2 2.2 Amplitude of pulses (V) Time (ns) measured simulated

h(t) =

1 2π

∞

−∞ S21(ω)ejωtdω

r(t) = ∞

−∞ h(τ)s(t − τ)dτ

Measured pulse: get impulse response h(t) by Inverse Fourier Transform of S21(ω) convolute h(t) with a source pulse r(t)

APMC 2003, Seoul, Korea – p.7/17

Single-band scheme I: source pulse

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Pulse amplitude (V) Time (ns) Time domain waveform 1e-11 2e-11 3e-11 4e-11 5e-11 6e-11 7e-11 8e-11 9e-11 1e-10 5 10 15 20 Spectrum density (V/Hz) Frequency (GHz) Frequency domain waveform

s(t) = t

σe−( t

σ )2

p(f) = −jπ1.5σ2fe−(πσf)2

where σ = 52ps

APMC 2003, Seoul, Korea – p.8/17

Single-band scheme II: emission level

• 80
• 75
• 70
• 65
• 60
• 55
• 50
• 45
• 40
• 35

2 4 6 8 10 12 14 Emission Spectra (dBmW/MHz) Frequency (GHz) 0.96 1.61 1.99 3.1 10.6 FCC’s indoor mask FCC’s outdoor mask Simulated:sigma=52ps Measured:sigma=52ps

Two ways to comply with the emission limits: Design an optimal source pulse. Use antenna to tailor the pulse spectrum.

APMC 2003, Seoul, Korea – p.9/17

Single-band scheme III: pulse detection

• 0.025
• 0.02
• 0.015
• 0.01
• 0.005

0.005 0.01 0.015 0.02 0.025 0.8 1 1.2 1.4 1.6 1.8 2 2.2 Amplitude of pulses (V) Time (ns) received pulse g4(t) sin(2πft)w(t)

f =

• T

0 sr(t)st(t)dt

T

0 s2 r(t)dt

T

0 s2 t(t)dt

• g4(t) = d4

dt4e−( t

σ )2

Template Parameter Fidelity

g4(t) σ = 74ps

96.6%

sin(2πfct)w(t) fc = 5.9GHz

82.6%

APMC 2003, Seoul, Korea – p.10/17

Multi-band scheme I: source pulse

In a 15 sub-bands scheme, the source signal has the form

• f s(t) = sin(2πfct)e−( t

σ )2, where σ = 1366ps and

fc = 3.35 + 0.5nGHz, n=0, 1, 2, ...... 15.

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 0.6 0.8 1 5 10 15 20 25 30 Amplitude of pulses (V) Time (ns) fc=3.35GHz fc=6.85GHz fc=10.35GHz

APMC 2003, Seoul, Korea – p.11/17

Multi-band scheme II: emission level

More freedom to control the emission level in a multi-band scheme. Transmitted power in different sub-bands can be controlled adaptively and separately to meet the emission limits. A sub-band can be turned off on the fly if there is strong interference from or to other equipments.

APMC 2003, Seoul, Korea – p.12/17

Multi-band scheme III: received pulses

• 0.04
• 0.03
• 0.02
• 0.01

0.01 0.02 0.03 0.04 20 40 60 80 100 120 Amplitude of pulses (V) Time (ns) 3.35GHz 3.85GHz 10.35GHz

Different magnitudes of the received pulses in different sub- bands.

APMC 2003, Seoul, Korea – p.13/17

Multi-band scheme IV: pulse detection

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Normalized spectrum density (V/Hz) Frequency (GHz) Source pulse Received pulse

The central frequency of a received pulse may differ from that of the source pulse in the same sub-band. Better to minimize such difference.

APMC 2003, Seoul, Korea – p.14/17

Multi-band scheme V: frequency error

ferror = fcreceiv − fcsource ferror are different in the 15 sub-bands.

• 0.01
• 0.005

0.005 0.01 0.015 0.02 0.025 0.03 3 4 5 6 7 8 9 10 11 Frequency error (GHz) Carrier frequency (GHz)

APMC 2003, Seoul, Korea – p.15/17

Conclusions

Wide bandwidth of S11(ω) and S21(ω) In a single-band scheme Complies with FCC’s emission limits when excited by a monocycle impulse. Obtains high fidelity in the pulse detection with proper template pulses. In a multi-band scheme Has more freedom to control the emission level. Shows different performances in different sub-bands.

APMC 2003, Seoul, Korea – p.16/17

Thanks! Question? http://www.geocities.com/xuanhui_wu

APMC 2003, Seoul, Korea – p.17/17