Energy weapon concept, credit: Pixabay, license: CC0 1.0
Microwave Based Weapons
Living in era of advanced warfare, modern military forces have always been searching for intelligent and improved strategies to counter artillery attacks. Microwave weapons in form of High Powered Microwave (HPM) is an emerging technology with all-weather capability and multiple target coverage. It produces a huge blast of microwave energy which can effectively damage the target’s electronic devices. The microwave energy is capable of damaging the circuits with overflowing currents among them. HPMs are also used to disrupt the enemy’s electrical signal systems for certain amount of time. HPMs have potential use in both defensive and attacking forces. Proving self defense against missile attacks along with the ability to interrupt enemy signals and security system makes HPM a viable weapon in battlefield.
Figure 1. Schematic diagram of microwave based weapons, credit: article author.
Microwave energy weapons are developed to disrupt and even destroy the enemy’s electronic device. This type of weapons operates in microwave frequency band from 10 MHz to 100 GHz. These weapons interact with the targets generally in two ways. To completely destroy the target device, the weapon is used to deploy high power which capable of heating the circuits of the target device up to melting point. This will cause severe internal damage to the target device. But using microwave energy on this type of operation is mostly dependent on the component materials of the target.
Causing electrical stimulation is the most efficient and practical use of microwave based weapon. The microwave energy produce stray currents and voltages to the target’s integrated circuits. These stray elements helps to disrupt the usual circuit operation of the device causing interruption in enemy’s signal and security system. The weapon interacts with the target device using components which are designed to receive signals like radar device. Besides signal receivers, any electrical conducting material of enemy device can be used as an antenna for the microwave energy weapons. HPMs have the potential to disable high valued target installations in densely populated area with minimal risk of civilian casualties as the human exposure to the HPM blast is barely harmful.
Components of HPM weapon
The main components of a HPM weapon are,
Along with these components, HPM weapons also have aiming, target tracking system and control mechanisms.
Pulse Power Source
Pulse power source is used to trigger the high power microwave source. A short pulse of about 1 MV is generated for a maximum duration of 1 micro second. The pulse is generated with the help of capacitor bank. Marx bank capacitor system is mostly used to convert low voltage signals to high voltage signals to generate the instantaneous pulse required in triggering operation. The capacitors are parallel connected at time of charging while connected in series when discharging. Figure 2 shows the charging and discharging state of a conventional Marx capacitor bank. Inductors are often used instead of resistors inside Marx bank to get higher repetition rates.
Flux compression generators are also often used alongside Marx bank. A magnetic coil is compressed by magnetic force inside the flux compression generator. This results in increase of current pulse inside the generator. Flux compression generators can be driven by explosion instead of magnetic force. But explosion based flux compression generators are one-time use system as equipment of the generator is being damaged after one operation.
High Power Microwave Source
HPM sources are of two types defined by Impulsive and Linear source in general. Impulsive source generates pulsed microwave energy by charging a tuned circuit or the antenna. The tuned circuit is ringed over a few cycles to generate the desired level of microwave energy. Ultra wideband microwave sources are the examples of impulsive source.
Linear HPM source converts kinetic energy of an electron beam into electromagnetic energy. When the velocity of the electrons passing electrostatic field is changed, bunches of electrons are produced. The velocity change is done by applying external voltage signal into the electron beam. Electron bunches then transfers the kinetic energy to radio frequency waves. This phenomenon is defined by velocity modulation. Magnetron is the example of most commonly used linear HPM source.
Transmitting antenna used as a medium of interface between the atmosphere and the high powered microwave source. The directivity of the weapon depends on the transmitting antenna. The HPM antennas need to support ultra wide bandwidth. Different types of horn antennas and antenna arrays can be used in HPM weapons.
Classification of HPM weapon
HPM weapons can be categorized in following forms,
Narrow-band HPM operates within a narrow bandwidth of frequency which is only a small part of center frequency. This type of HPM generates much higher power in output. Narrow-band HPMs are used only over specific target which are capable of absorbing the emitted frequency of the system. The advantage of narrow-band HPM is better transmission characteristics and much higher power output, while necessity of knowledge about target material is the major drawback of this type of HPM weapons.
Ultra wide-band HPM
Ultra wide-band HPM operates over a larger frequency bandwidth. It generates comparatively fewer amount of microwave output than narrow-band HPM. The broad range of frequency enables it to be used against a wide range of targets. The advantage of using ultra wide-band HPM is to interact with several target simultaneously and no prior information about the target material is needed. Due to the lower microwave output, this type of weapons have shorter operational range.
Capabilities & Limitations of HPM Weapons
Some of the major capabilities of High Powered Microwave Weapons are described below,
HPM weapons have some limitations also. Some of the major drawbacks of this weapon technology is given below,
High Powered Microwave weapons generates blast of strong microwave energy which is capable of damaging the targeted electronic devices. A sudden increase in voltage and current flow cause malfunctioning in the enemy electronic system. HPM weapons with their all-weather capability and larger footprint are considered to be a feasible offensive weapon in modern battlefield.
The next article of this series will be about a detailed overview on “Laser Based Weapons”. Technical features, operational details along with their effect and advantages will be discussed. Feel free to drop any suggestion or inquiries about laser weapons in comments section, I’ll try to include that in my next article.
I'm sincerely grateful to @scienceangel for her guidance and help in writing this article.
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