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Wang Electro-Opto Corporation ( )WE O ®®
Broadband Omnidirectional Helmet Antennas
Johnson J. H. Wang
Wang Electro-Opto CorporationMarietta, Georgia 30067 USA
Presented in the 2006 IEEE AP-S International Antenna SymposiumAlbuquerque, NM
July 12, 2006
This research is partially supported by US Army CERDEC, Ft. Monmouth, NJ.
Wang Electro-Opto Corporation ( )WE O ®®
Outline
• Motivation
• Approach
• Brassboard Models and Field Tests
• Fieldable Retrofittable Model and Lab Tests
• Concluding Remarks
Wang Electro-Opto Corporation ( )WE O ®®
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 ( )WE O ®®
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 ( )WE O ®®
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 ( )WE O ®®
RF design goals
• Frequency bandwidth: 1.35 – 2.7 GHz
• Polarization: vertical
• Radiation pattern: omnidirectional
Wang Electro-Opto Corporation ( )WE O ®®
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 ( )WE O ®®
Three models developed
• Two brassboard models (“Wang Ph 1” and “Wang Ph 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 ( )WE O ®®
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 !
Good Comms InGood Comms InAll DirectionsAll Directions
Good Comms InGood Comms InAll DirectionsAll Directions
No Body Blockage !
WANG BODY WEARABLE HELMET ANTENNA
Quick Connect / Disconnect Connector
No Comms In No Comms In This DirectionThis Direction
No Comms In No Comms In This DirectionThis Direction
Body Blocks Comm in Forward
Direction !
TYPICAL DISMOUNTED WHIP ANTENNA
vs
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 ( )WE O ®®
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
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 Ronald D. of 104th CAV wearing the Wang Phase II helmet
Better RF Range Performance than Larger, Narrowband Whip Antenna
Material courtesy of U.S. Army CERDEC
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
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
Wang Electro-Opto Corporation ( )WE O ®®
Annular zone on helmet clear of obstructions for optimal performance
No obstructions allowedin the annular zone
Wang Electro-Opto Corporation ( )WE O ®®
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 ( )WE O ®®
Measured Standing Wave Ratio (SWR)
Model #A123J14
2
1
Wang Electro-Opto Corporation ( )WE O ®®
Measured radiation patterns over 1.35–2.7 GHz
Elevation
Model #A123J14
5 dB/div
1.350 GHz 1.800 GHz 2.700 GHz2.250 GHz
y
x
φ
θ = 90°
Azimuth
1.350 GHz 1.800 GHz 2.700 GHz2.250 GHz
z
x
θ
φ = 0°
Wang Electro-Opto Corporation ( )WE O ®®
Measured peak gain over 1.35 – 2.7 GHz
Model #A123J14
Peak Gain
-10.0
-5.0
0.0
5.0
10.0
1 1.5 2 2.5 3
Frequency, GHz
Pea
k G
ain
, dB
i
Discone on 24" gnd plane
Wang Helmet AntennaModel#A123J14
Pea
k G
ain
, dB
i
Wang Electro-Opto Corporation ( )WE O ®®
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 ( )WE O ®®
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