Driving down the interstate, you pass a car on the shoulder that had been stopped by the police cruiser parked behind it. Seems like a normal occurrence, especially for some motorists who routinely exceed the posted speed limits. What you don't know is how the police stopped the car. No high-speed chase with the potential of causing a serious accident was necessary. The officer just activated the high-power electromagnetic system (HPEMS) on the roof of the cruiser which stopped the car.
Definitely not a new concept, a prototype system was first tested in 1997 by the U.S. Army using military-grade equipment, according to a recent article published in the MIT Technology Review. What is mounted on the police cruiser's roof is vastly different from that first unit.
Under development by a small company in California, Eureka Aerospace, HPEMS uses microwave signals to immobilize the electronic control systems in vehicles. Beamed from an antenna on top of the police cruiser, the microwave pulses are designed to upset or damage any microprocessor-based units in the car such as ignition control, fuel delivery, anti-lock braking, and vehicle stability control.
As noted on the company's website, the HPEMS includes three major components: a power source, tunable RF oscillator, and high-gain antenna. The power source is a 16-stage Marx generator that has an input of 270 VDC and generates an output of high-energy pulses at 640 kV with a PRF of 100 Hz. The tunable oscillator is a two-plate variable-length transmission line in conjunction with several spark gap switches that convert the pulses to adjustable frequencies that range from 350 to 1,350 MHz. The antenna mounted on the roof of the police cruiser has a gain of 16 to 28 dBi corresponding to the range of transmitted frequencies. The overall system is expected to deliver at least 20 kV/m at a distance of up to 50 m.
What I found disconcerting is the apparent lack of current information on the company's website. For instance, the last news item entry was dated June 2005. Have not any newsworthy events happened at the company after that date to warrant more current postings? Also, in the Current State of Development section of the website, a prototype HPEMS was expected to be completed by October 2005 and mounted on a Ford Crown Victoria with full-scale testing at the Los Angeles Sheriff's Department in November 2005. Was the prototype testing completed and successful? As reported in a recent MIT Technology Review article, the CEO of Eureka Aerospace states that stationary vehicle testing has been completed and actual highway testing could occur within 18 months. Does Ford still make the Crown Victoria?
Microwave pulses beamed at a vehicle that can upset and damage microprocessors also might be of concern to the car's occupants. Are there any health-related issues for the driver and passengers that must be considered?
Is it possible to accurately focus the signal beam from the cruiser at only the offending vehicle and not other vehicles or pedestrians in the vicinity? Also, what happens when the control systems in the car are disabled? Does the car stop immediately, or does it coast for a short distance? Does the anti-lock braking system become inoperable? Can the driver still steer the car? All of these issues and more must be addressed and resolved long before actual field deployment.
Paul Milo
Editorial Director
[email protected]