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, S 11 ( ω ) and S 21 ( 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 0 -20 S-parameter (dB) -40 -60 Measured S11 -80 Simulated S11 Measured S21 Simulated S21 -100 0 2 4 6 8 10 12 14 16 18 Frequency (GHz) -10dB bandwidth of | S 11 ( ω ) | : 6.8GHz - 15GHz -3dB bandwidth of | S 21 ( ω ) | : 5.0GHz - 14.6GHz APMC 2003, Seoul, Korea – p.6/17

TD responses 0.025 0.02 Amplitude of pulses (V) 0.015 0.01 � ∞ 1 −∞ S 21 ( ω ) e jωt dω h ( t ) = 0.005 2 π 0 � ∞ r ( t ) = −∞ h ( τ ) s ( t − τ ) dτ -0.005 -0.01 -0.015 measured simulated -0.02 0.8 1 1.2 1.4 1.6 1.8 2 2.2 Time (ns) Measured pulse: get impulse response h ( t ) by Inverse Fourier Transform of S 21 ( ω ) convolute h ( t ) with a source pulse r ( t ) APMC 2003, Seoul, Korea – p.7/17

Single-band scheme I: source pulse Time domain waveform Frequency domain waveform 1 1e-10 0.8 9e-11 Spectrum density (V/Hz) 0.6 8e-11 Pulse amplitude (V) 0.4 7e-11 0.2 6e-11 0 5e-11 -0.2 4e-11 -0.4 3e-11 -0.6 2e-11 -0.8 1e-11 -1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 5 10 15 20 Time (ns) Frequency (GHz) σ e − ( t σ ) 2 s ( t ) = t p ( f ) = − jπ 1 . 5 σ 2 fe − ( πσf ) 2 where σ = 52 ps APMC 2003, Seoul, Korea – p.8/17

Single-band scheme II: emission level -35 0.96 3.1 10.6 Emission Spectra (dBmW/MHz) -40 -45 1.99 -50 1.61 -55 -60 -65 FCC’s indoor mask -70 FCC’s outdoor mask -75 Simulated:sigma=52ps Measured:sigma=52ps -80 0 2 4 6 8 10 12 14 Frequency (GHz) 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 received pulse 0.02 g4(t) sin(2 π ft)w(t) 0.015 Amplitude of pulses (V) � � 0.01 � T � 0 s r ( t ) s t ( t ) dt � 0.005 = f � � �� T � T 0 � � r ( t ) dt 0 s 2 t ( t ) dt 0 s 2 � � -0.005 g 4 ( t ) = d 4 dt 4 e − ( t σ ) 2 -0.01 -0.015 -0.02 -0.025 0.8 1 1.2 1.4 1.6 1.8 2 2.2 Time (ns) Template Parameter Fidelity 96.6% g 4 ( t ) σ = 74 ps sin (2 πf c t ) w ( t ) f c = 5 . 9 GHz 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 of s ( t ) = sin (2 πf c t ) e − ( t σ ) 2 , where σ = 1366 ps and f c = 3 . 35 + 0 . 5 nGHz , n =0, 1, 2, ...... 15. 1 0.8 0.6 Amplitude of pulses (V) 0.4 0.2 0 -0.2 -0.4 -0.6 f c =3.35GHz f c =6.85GHz f c =10.35GHz -0.8 -1 5 10 15 20 25 30 Time (ns) 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 Amplitude of pulses (V) 0.02 3.85GHz 0.01 0 -0.01 3.35GHz -0.02 -0.03 10.35GHz -0.04 0 20 40 60 80 100 120 Time (ns) Different magnitudes of the received pulses in different sub- bands. APMC 2003, Seoul, Korea – p.13/17

Multi-band scheme IV: pulse detection 1 Normalized spectrum density (V/Hz) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 Source pulse 0.1 Received pulse 0 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Frequency (GHz) 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 f error = fc receiv − fc source f error are different in the 15 sub-bands. 0.03 0.025 Frequency error (GHz) 0.02 0.015 0.01 0.005 0 -0.005 -0.01 3 4 5 6 7 8 9 10 11 Carrier frequency (GHz) APMC 2003, Seoul, Korea – p.15/17

Conclusions Wide bandwidth of S 11 ( ω ) and S 21 ( 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