uwb antenna ryan clarke roshini karunaratne chad schrader advisor: ray kwok
TRANSCRIPT
UWB Antenna
Ryan ClarkeRoshini Karunaratne
Chad Schrader
Advisor: Ray Kwok
Objectives
• Design UWB antenna for hand held communication device (walkie-talkie)
• Use Iterative simulation to arrive at design
Specifications
• 225 – 400 MHz
• VSWR < 1.5 : 1
• Efficiency > 75%
• Proximity Insensitive
• Broadband
Design Issues
• Small enough for a handheld device
(H = 10”, W = 3”, T = 1”)
• Broadband
• High Bandwidth factor (~70%)
• Non-dispersive
Antenna TopologiesConsidered
• Diamond Dipole
• PIFA (Planar Inverted-F Antenna)
• Dual L-shaped Monopole
Diamond Dipole
• Poor frequency response for 225 – 400 MHz
• Dimensions too big
PIFA
• Poor frequency response for 225 – 400 MHz
• Dimensions too big
Dual L-Shaped Monopole(Success!)
• VSWR < 1.9 for 270 – 400 MHz• Efficiency• Omni-directional
Simulation Results
• Optimized dimensions
• VSWR
• Radiation Pattern
• E-fields and H-fields
Optimized Dimensions
• Dimensions optimized by simulation software
• H = 236mm, 9.3in
• W = 31.5mm, 1.24in
• Pipe diameter, d = 7.5mm, 0.3in
VSWR
• VSWR < 1.9 for 270.9 – 404.3 MHz
• VSWR < 1.5 not achieved
• Mid-band VSWR minimum is ~ 1.7
Radiation Pattern
• Omni-directional
• f = 225 MHz, Gain[phi] = 5.2 dB
• f = 350 MHz, Gain[phi] = 6.0 dB
• f = 400 MHz, 3.5 dB < Gain[phi] < 6.9 dB
F = 225 MHz
F = 225 MHz
F = 350 MHz
F = 350 MHz
F = 400 MHz
F = 400 MHz
E-Fields and H-Fields
• Distribution at corners
• Surface current
• Proximity sensitivity
Construction
• Copper pipe– Best available conductor
• Ground plane– Large as possible (can’t do infinite)
• Insulators
– Lowest εr, rubber (εr = 2)
• Coaxial cable and connectors– APC7, N-type
Costs
• Copper tube, $12/ft.
• Ground plane, $5-$10
• Mounting hardware, $2
• Total Cost, $30 - $35
Testing
• Network analyzer >>> return loss curve
• Proximity sensitivity
• Radiation pattern
Conclusion
• Simulated double-L monopole antenna
• Simulation results encouraging
• Prototype construction in progress
The End.
Questions?