JED - January 2016 - (Page 34)

EW 101 Directed Energy Weapons - Part 4 High Power Radio Frequency Weapons By Dave Adamy T The Journal of Electronic Defense | January 2016 34 his month's column and next month's are based on information in several papers on the Internet; two particularly useful sources are a tutorial by George H. Baker and a Wikipedia article. Another important source is Dr. Curt Schleher's book, Electronic Warfare in the Information Age. High power radio frequency (HPRF) weapons are also called high power microwave (HPM) weapons. These weapons typically operate in the millimeter wave region, so in this discussion, we will use the term HPRF. The range of their operational application varies from the high end of nuclear electromagnetic pulse (EMP) to the low end of non-lethal systems for crowd control. They are of particular interest to military users for information warfare and missile defense applications. They are also used by civilian police departments. Simply put, HPRF weapons transmit high levels of RF energy to degrade the performance of, or destroy, a target. The radio waves travel at the speed of light and can be effective in seconds. There are three critical considerations in HPRF weapons: the actual weapons, radio propagation and the target response as shown in Figure 1. oscillator. It also must have an antenna. In his 1999 text book, Dr. Schleher has a figure that shows power output capabilities in the millimeter frequency range for various types of transmitters. A Vircator is shown to output 1 Gigawatt, a Gyrotron's output is shown with capability up to about 500 Megawatts and a Magnetron's output is shown up about 50 Gigawatts. This figure (based on 1988 IEEE data) shows that the power output declines with increasing frequency. Dr. Schleher's data also mentions free electron lasers (discussed last month) as Gigawatt power sources at millimeter wave frequencies. Continuing research and development is expected to yield increasing power levels and operating frequencies for these and other transmitter types as time goes on. Antenna gain is a function of the antenna aperture. The formula for antenna gain vs. antenna size is: G = (π2 D2) / λ2 Where: D is the diameter of a dish in meters and λ is the signal wavelength in meters. In terms of the effective antenna area, the approximate gain is: THE WEAPON An HPRF weapon has a power source and a transmitter, such as a magnetron, a vircator, a gyrotron, or a backward wave Radio Freq. Weapon ANTENNA TRANSMITTER G = (4π A) / λ2 Target Response WAVE PROPAGATION Package Penetration ENEMY ASSET Component Entry Failure Through Antenna POWER SOURCE Figure 1: The three elements of an HPRF weapon system are the weapon, wave propagation and the target response. Figure 1: Thet three elements of an HPRF weapon system are the weapon, wave propagation and the target response.

Table of Contents for the Digital Edition of JED - January 2016

The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
World Report
On the Brink: Laser Wars Not Just a Movie Fantasy
Light Saber – LaWS Prototype Brings Directed Energy Onto the Front-Line
Technology Survey: RF Signal Generators
Threat Monitor
EW 101
AOC News: Views from the AOC Symposium and Convention
AOC News
Index of Advertisers
JED Quick Look

JED - January 2016