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?