Broadband Omnidirectional Helmet Antennas Johnson J. H. Wang Wang Electro-Opto Corporation Marietta, Georgia 30067 USA

1. Broadband Omnidirectional Helmet Antennas Johnson J. H. Wang 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 partially supported by US Army CERDEC, Ft. Monmouth, NJ. Wang Electro-Opto Corporation ( )

2. Outline • Motivation • Approach • Brassboard Models and Field Tests • Fieldable Retrofittable Model and Lab Tests • Concluding Remarks Wang Electro-Opto Corporation ( )

3. Motivation • A helmet is generally worn in the field by soldier, police, firefighter, forest worker, and motorcycle rider, etc. • The helmet-mounted antenna is the only antenna carried, borne, or worn by them that can possibly have a true and stable omnidirectional radiation pattern because of its • uniquely high and unobstructed field of view • stable orientation independent of the posture and movement of the wearer (since the head is generally held upright). Wang Electro-Opto Corporation ( )

4. Difficulties for helmet antennas Helmet antennas in the literature are in early stages of development, with electrical and physical performance grossly below the expectations of user community due to the following difficulties. • Antenna gain-bandwidth limited by helmet size • Safety issues on RF radiation and ballistic hazard • Stringent weight and size limitation • Competition for premium helmet location with other equipment Wang Electro-Opto Corporation ( )

5. The present approach • Based on WEO’s patented SMM (spiral-mode microstrip) antenna and slow-wave antenna technology • ultra-wideband/multiband • has inherent ground plane to shield the wearer from radiation hazard Wang Electro-Opto Corporation ( )

6. RF design goals Frequency bandwidth: 1.35 – 2.7GHz Polarization: vertical Radiation pattern: omnidirectional Wang Electro-Opto Corporation ( )

7. Other design goals Safety requirements on RF radiation ANSI/IEEE standard for “Uncontrolled Environment” Minimal ballistic effect to head of wearer Maximum weight: 2 oz (56.7 gm) Retrofittable to kevlar helmets Producibility and low cost Wang Electro-Opto Corporation ( )

8. Three models developed Two brassboard models (“Wang Ph 1” and “WangPh 2”) were developed first both field tested by the US Army results summarized by the following two PPT slides prepared by Army CERDEC A fieldable retrofittable model recently developed meeting all design goals in WEO lab tests currently being field tested by Army CERDEC Wang Electro-Opto Corporation ( )

9. Current Antennas Used for the Dismounted Soldier • Pronounced Profiles - Easily Spotted By Enemy • Susceptible to Body Blockage Effects - Poor Communications in Certain Directions • Susceptible to Damage from Foliage & Obstructions - No Comms ! • Are Narrowband and Tailored to a Single System - Can’t Support New JTRS & SLICE Waveforms ! TYPICAL DISMOUNTED WHIP ANTENNA WANG BODY WEARABLE HELMET ANTENNA No Comms In This Direction Good Comms In All Directions vs Body Blocks Comm in Forward Direction ! No Body Blockage ! Quick Connect / Disconnect Connector • Covers SLICE Soldier Radio Waveform (1350-2700 MHz) • Antenna Weight : 4 oz • Can Be Retro-Fitted To Existing Helmets In Field • Cost Effective - Reduced Attrition Rates Material courtesy of U.S. Army CERDEC Wang Electro-Opto Corporation ( )

10. C4ISR Demonstration Process • Line-of-sight Range Measurements (Whips and Helmets) • Evaluate Range Measurements • Perform a Voice Communication Test With ARC Radio System Using the 802.11 Whip Antennas and Helmet Antenna • Perform a Data Transmission Test Using the Commander Handheld Application for Mission Planning (CHAMP) Software Using the 802.11 Whip Antennas and Helmet Antenna • Evaluate Performance of Helmet Antenna Based on Soldiers’ Comments Specialist E4 RonaldD. of 104th CAV wearing the Wang Phase II helmet • Notable Features - Helmet Antenna • Completely Reduces the Visual Signature - No Bending Required ! • Not Subjected to Body Blockage • Isolated From Metallic Obstructions in the Soldier Wear • Wide Band Operation Better RF Range Performance than Larger, Narrowband Whip Antenna Material courtesy of U.S. Army CERDEC Wang Electro-Opto Corporation ( )

11. Annular zone on helmet clear of obstructions for optimal performance No obstructions allowed in the annular zone Wang Electro-Opto Corporation ( )

12. The latest fieldable retrofittable model Meeting ALL the design goals 2 oz (56.7 gm) in weight Currently being field tested by the US Army Wang Electro-Opto Corporation ( )

13. Measured Standing Wave Ratio (SWR) 2 1 Model #A123J14 Wang Electro-Opto Corporation ( )

14. z y φ θ x x Measured radiation patterns over 1.35–2.7 GHz Azimuth θ = 90° 1.350 GHz 1.800 GHz 2.250 GHz 2.700 GHz 5 dB/div Elevation φ = 0° 1.350 GHz 1.800 GHz 2.250 GHz 2.700 GHz Model #A123J14 Wang Electro-Opto Corporation ( )

15. Peak Gain, dBi Measured peak gain over 1.35 – 2.7 GHz Model #A123J14 Wang Electro-Opto Corporation ( )

16. Fieldable retrofit helmet antenna weighs only 2 oz • Antenna assembly made of lightweight foam, thin copper sheet, PC board, and flexible feed cable in a thermochemical composite • Conductive foil lining shielding wearer’s head • Quick-snap-on connector at helmet edge Wang Electro-Opto Corporation ( )

17. Conclusion • A fieldable retrofittable helmet antenna covering 1350-2700 MHz has been developed. • It has major advantages over other antennas: • invisible and safe • stable and broad omnidirectional coverage • weighs only 2 oz • rugged (can withstand up to 70 lbs or more) • field retrofittable • producible at competitive cost Wang Electro-Opto Corporation ( )