A Multioctave Broadband Vest Antenna Based on SMM Antenna Technology Johnson J. H. Wang and David J. Triplett* Wang Ele

1. A Multioctave Broadband Vest Antenna Based on SMM Antenna Technology Johnson J. H. Wang and David J. Triplett* Wang Electro-Opto Corporation Marietta, Georgia 30067 USA Presented in the 2006 IEEE AP-S International Antenna Symposium Albuquerque, NM July 12, 2006 This research is supported by US Army CERDEC, Ft. Monmouth, NJ. Wang Electro-Opto Corporation ( )

2. Outline • Motivation • Approach • Brassboard Models • Measured Performance • Concluding Remarks Wang Electro-Opto Corporation ( )

3. Motivation • Mobile soldiers, police, firefighters, forestry workers, etc. need “hands free” operation for their wireless equipment. • A solution is to use antennas borne or worn on their upper torso (as vest antenna). Wang Electro-Opto Corporation ( )

4. Prior known vest antennas have severe shortcomings • No conductive shielding against radiation hazards to wearer • acceptable in research and test stage under the “controlled environment” exclusion clause • unacceptable for deployment since vest antennas are worn regularly, thus in an “uncontrolled environment” • Poor gain pattern • low gain • poor omnidirectional coverage • rapid oscillatory spatial variations Wang Electro-Opto Corporation ( )

5. Safety issues on RF radiation hazard for vest antennas — serious yet overlooked • Vest antenna designs must be based on an “uncontrolled environment” scenario (like the cell phone), since they are worn continually, though by professionals. • At 300-3000 MHz, PEL (Permissible Exposure Limit) for uncontrolled environment is five timeslower than that for controlled environment. Wang Electro-Opto Corporation ( )

6. Radiation hazard is a critical issue for body worn antennas • Most cell phones barely meet the 1.6 W/kg SAR (Specific Absorption Rate) limit, even at the typical 0.25 W power. • JTRS (Joint Tactical Radio System) mobile radios aim at 5 W power. Wang Electro-Opto Corporation ( )

7. The present approach • Based on the SMM (spiral-mode microstrip) antenna technology • Ultrawideband (multioctave) • has inherent ground plane to shield the wearer from radiation hazard Wang Electro-Opto Corporation ( )

8. Design goals Frequency of operation 0.225 – 1.0 GHz Polarization circular polarization Radiation pattern omnidirectional coverage with minimal spatial dips Safety requirements on RF radiation ANSI standard for “Uncontrolled Environment” Wang Electro-Opto Corporation ( )

9. A 2-element vest array of SMM antennas Wang Electro-Opto Corporation ( )

10. Military gear onto which vest antenna can be installed z x Wang Electro-Opto Corporation ( )

11. Representative azimuth patterns on saline mannequin(pseudo-circular polarization) y VP 5dB/div x HP 0.225 GHz 0.5 GHz 1.0 GHz Wang Electro-Opto Corporation ( )

12. Measured peak antenna gain in the azimuth plane Wang Electro-Opto Corporation ( )

13. Measured SWR of front element antenna 2 1 Wang Electro-Opto Corporation ( )

14. Key advantages of SMM vest antenna over whip Wang Electro-Opto Corporation ( )

15. Major disadvantages of this vest antenna • Weight: • currently 4.4 lbs. • reducible to 1.5 lbs. • Disruption by other body borne gear Wang Electro-Opto Corporation ( )

16. Concluding Remarks • A multioctave broadband vest antenna based on the SMM antenna technology has been developed. • The brassboard model exhibits considerably better performance than other known vest antennas. • It has major advantages over the whip antenna: much wider bandwidth, invisible, safer, and more stable connectivity. • It should be able to meet ANSI safety requirements on RF radiation hazard. • It has disadvantages of weight and disruption by other body-worn gear. Wang Electro-Opto Corporation ( )