High Power Microwave (HPM) Weapons: Types and Applications

This article delves into High Power Microwave (HPM) weapon systems, a type of directed energy weapon. We’ll explore the components, functionality, advantages, and disadvantages of these systems, which are designed to disrupt, degrade, or destroy enemy electronic systems and circuits.

Microwave weapon systems leverage electromagnetic radiation in the microwave band, typically operating between 500 MHz and 3 GHz, although the microwave band itself spans from 300 MHz to 300 GHz. Current research focuses on developing non-lethal weapons around 100 GHz, exploring their effects on humans.

Because these weapons utilize high energy and directional beams, they are classified as directed energy weapons.

Applications of High Power Microwave Weapon Systems:

• Damage or destroy electronic systems/circuits with minimal or no casualties.
• Suppress enemy air defense systems.
• Target chemical/biological weapon facilities, as HPM weapons don’t release deadly toxins.

High Power Microwave Weapon System Block Diagram

Figure 1 illustrates a typical block diagram of an HPM weapon system, comprised of the following modules:

• Pulse Power Source
• HPM Source
• Antenna

Pulse Power Source

This module consists of a power supply and a pulse generator.

Function: Pulse power generators must deliver short, intense electrical pulses of 1 MV or more, with pulse durations of less than 1 µs. Achieving this can be done in several ways, depending on the type of HPM source used:

• Capacitor Banks: These systems convert slow-rise, low-voltage signals into fast-rise, high-voltage signals through a charging process.
• Inductor Charging: This method provides a high repetition rate, typically a few Hz or more.
• Flux Compression Generator: This involves compressing a magnetic coil using explosives or magnetic forces, leading to a sharp rise in current pulse.

HPM Source

HPM sources fall into two main categories: impulsive sources and linear beam sources.

• Impulsive Sources: These sources generate pulsed microwave energy by directly charging an antenna, transmission line, or tuned circuit, then allowing them to “ring” for multiple cycles by closing a switch. Example: Ultra-wide band sources.
• Linear Beam Sources: These sources convert the kinetic energy of an electron beam into electromagnetic energy in the form of a microwave beam. Examples include: Klystrons, TWT (Traveling Wave Tube), BWO (Backward Wave Oscillator), Magnetron, CFA (Cross-Field Amplifier), Virtual Cathode Oscillator, Gyrotron, Split Cavity Oscillator, Free electron laser, Orbitron Microwave Maser.

Antenna

The antenna transmits the microwave frequency to the intended target. It acts as an interface between the microwave source and the atmosphere.

Types of High Power Microwave Weapons

There are two primary types of HPM weapons:

• Narrow band HPM
• Ultra-wide band HPM

Narrow Band HPM

Narrow band HPM radiates microwave energy within a narrow frequency range, typically within a few percent of the center frequency, often in the tens to hundreds of MHz. It generally uses higher power compared to ultra-wide band HPM.

Advantages:

• Better transmission characteristics.
• Fewer issues with fratricide (friendly fire).

Disadvantages:

• Requires prior knowledge of the target material to determine the optimum microwave frequency.
• Effective only on specific types of targets.

Ultra-Wide Band HPM

Ultra-wide band HPM radiates energy over a wide range, from hundreds of MHz to several GHz.

Advantages:

• Can be used against a wide range of targets.
• Does not require prior knowledge of the target’s absorption characteristics.

Disadvantages:

• Shorter range due to lower radiated power and poorer transmission characteristics compared to Narrow band HPM.

Advantages of High Power Microwave Weapon Systems

• Speed of Light Operation: Delivers results almost instantaneously.
• Weather Independent: Not affected by weather or atmospheric conditions.
• Large Area Coverage: Effective over large areas, depending on beam divergence, transmit power, and distance from the target.

Disadvantages of High Power Microwave Weapon Systems

• Uncertainty of Damage Assessment: Difficult to accurately assess the extent of damage caused.
• Short Range: Shorter range compared to high-energy laser weapon systems.