Ultrawideband Antennas

Transkript

1 Ultrawideband Antennas Dr.-Ing. Frank Sabath Overview Introduction Requirements Types of Antennas Recent Developments System Integration Discussion of Applications Open Questions / Challenges 1

2 Areas of Application Directed Energy Weapons / HPM-Weapons IEMI Simulator UWB-Antennas UWB Communication - Pulse Radio UWB-Radar -High Resolution - Ground Prenetation Principle of Action RF Source / Weapon Generator: Size Energy Repetition Rate Atmosphere Target System Pulse Forming: Bandwidth? Repetition Rate? Antenna directivity? bandwidth? 1 P 2 r E 1 r Shell: Transfer Function? Type of Target? Electronic: Energy? Voltage? T r a n s fe r fu n k tio n T ransferfunktion in V p r o V p r o m f in M H z 2

3 Field Signal Prepulse Main Pulse Classification b r b r Band Ratio fh 2 + BF = = f 2 f B h upper limit l F B F Fractional Bandwidth f l lower limit Band ( IEC ) b r Band (DARPA) Narrowband (NB) b r 1.01 Mesoband (MB) 1.01 < b r 3 Sub-Hyperband (SHB) 3 < b r 10 b r 1.01 (B F 0.01) 1.01 < b r 1.29 (0.01 < B F 0.25) 1.29 < b r (0.25 < B F 2) (NB) (WB) (UWB) Narrowband Wideband Ultra- Wideband Hyperband (HB) 10 < b r 3

4 Requirements General Applicable Directivity / Gain Size / Weight Low Reflection Rate Impulse Radiation Constant (Linear) Behavior in the MHz GHz range Dispersion Less (linear decrease of phase) No Ringing High Power High Voltage at Feed Acceptable Input Impedance HPM (Narrowband) Horn-Antennas Reflector Antennas Phased-Arrays Types Active Denial System In Principle RADAR Antenna Modified for High Power Feeding / Radiation MTF SUPRA MTF 4

5 Types UWB (Sub-Hyperband / Hyperband) Small Dipole (Bi- ) Cone Antenna TEM-Horn Reflector Type Impulse Radiation Antenna (IRA) Array Antenna Dipol- / Cone Antenna 5

6 Reflector Type IRA WIS Farr Research AFRL WIS TEM-Horn 6

7 Array Antenna Developments Collapsible Reflector Type IRA Parachute IRA High Power UWB Radiator (Half IRA) Optimization of Feeding Structure Optimization of Termination Optimization of Aperture Distribution (Directivity, Radiation Efficiency) Adaptation on various Sources New Materials 7

8 Collapsible Reflector Type IRA Challenge: low weight space needed for storage / transportation required gain -> aperture diameter Solution: umbrella like structure conducting fabric Challenge: integration in an artillery system shock resistance before activation: < 0.2 m required gain -> > 2 m Parachute IRA Solution: conducting fabric integration of a reflector type IRA in a parachute 8

9 Half IRA Challenge: adaptation of high power sources weight some 100 kg metallic tube with > 0.2 m need of a high voltage balun fast rise time of voltage / field signal Solution: employing of mirror principle by feed over metallic plate decoupling of antenna and source region no balun needed reduced size Optimization of Feeding Structure Challenge: 1. Feeding with high voltage (prevention of sparking) 2. Conversion of phase front (plane wave to spherical wave) 3. Optimal illumination of aperture (directivity, efficiency) Solution: 1. Dielectric material (oil, plastic, ceramic) 2. Wave Forming Lens 3. Variation of Feed Arms (Orientation) Tapering of Reflector Shape 9

10 Applications Ship Self Defense Neutralization of IED s Protection against IED s UWB War Head - Parachute IRA - HPM / UWB UCAV Ship Self Defense Integration Concept Control System Integrated in Combat Direction System (CDS) Interface to CDS HPM Source HV Support Antenna Arrays conformal to hull 10

11 HPM has the ability Ship Self Defense to react with the speed of light (imediate reaction) to cause malfunctions and demages in the guidance section m m m m 1500 m 5000 m 5000 m 3000 m 1500 m Neutralisation of IED s HPEM has the ability To bar remote controlled booby traps from triggering to pretrigger electronic controlled booby traps HPEM Jammer HPEM IED Actuator Car bombe (RF controlled) IED with Distance Actuator Remote Controlled IED Observer 11

12 Protection against IED s Adaptive Protection Device 2 antenna units mounted on the front of the vehicle for prematurely detonation of electronical IEDs Protection against IED s Adaptive Protection Device 3 to 4 antenna units mounted on the outside of the vehicle for the main directions power supply and controls are placed inside the vehicle master slave operation 12

13 Reflector UWB War Head Waveguide Parachute Radiated Field Target UWB Source Parachute IRA 13

14 HPM / UWB UCAV Challenges Feed Electric Strength Load Matching Termination Suppression of reflections (ringing) System (Platform) Integration Space / Weight Interaction with Platform (Backscattering) 14

15 Thank You for Your Attention Author Dr.-Ing. Frank Sabath High Power Microwave Branch () Federal Armed Forces Research Institute for Protective Technologies (WIS) P.O. Box 1142, Munster, Germany Phone: +49 (0) Fax: +49 (0)