In Person Activism

Sadly, the video refuses to play continuously for me (likely due to an interaction between ads and ad blocker).

In case this also annoys others, here's some information as text. :) It's about protecting unmanned aerial vehicles, not people, however.

• microwave frequencies can be picked up by cable runs in the range 3 mm to 20 cm
• microwaves cause noise in a drone's internal systems and lead to malfunction
• the most vulnerable component is an operational amplifier
• communication equipment is severely affected
• as expected, optical and fiber optical communications are immune
• shielding: provides a continuous layer of conductive material
• some conductive materials are better than others
• shielding materials: aluminum, copper, nickel (note: magnetic) and their alloys, foil or mesh, graphene and graphene oxide as paint

Below, you can find a nice enough study written by a major in the USAF for his master's thesis, about hardening UAV systems against microwave weapons. It's only partly outdated.

https://apps.dtic.mil/sti/tr/pdf/AD1042082.pdf

I picked out some information:

Units of measurement: volts per meter (electrical field strength), watts per square centimeter.

Factors specific to the weapon include power level, microwave frequency, pulse duration, and pulse repetition interval.[18] This pulse creates an electromagnetic (EM) field surrounding the target, typically measured in volts per meter, kilovolts per meter, or watts per square centimeter (V/m, kV/m, W/cm2 ). The field produces excess energy, energy potential, or power within the target, measured in joules (J), volts (V), or amps (A). The aim is to induce a strong enough flow of electrons in the target material to cause adverse effects. [19] Field strength decreases proportional to the inverse square of target range (r), or 1/r2 , assuming a directional antenna as the source of the pulse.

Paths of effect: "front door" through antennas, "back door" through the entire system.

The energy that reaches the target induces effects by coupling to the component in one of two ways. “Front door” coupling occurs when energy enters the system directly through a normally utilized input device, such as an antenna. This type of coupling typically only occurs within the narrow band of the EMS that the input device was designed to receive. “Back door” coupling is the entrance of energy into the system by the field of electric potential that surrounds it. Back door coupling is more difficult to protect against, as the weapon does not need to be designed to match input device characteristics, allowing a much wider frequency band.[20]

Most vulnerable parts: op-amps, MESFETs (note: not MOSFETs).

Operational amplifiers, widely used in integrated circuits, as a common component vulnerable to upset, with a threshold of 9x10 -10 J. Among common components most susceptible to damage are Gallium arsenide metal- semiconductor field-effect transistors (GaAs MESFET), used in radar and sensor systems, with a damage threshold as low as 10 -7 J.22 While upset and damage effects to common electronic components from back door coupling are typically associated with field strengths of 8 kV/m [14] (upset) and 15 to 20 kV/m (damage), AFRL considers a field of electrical potential of 200 V/m or stronger as a threat to sensitive electronics in general.[23] This field strength is readily attainable with current HPM systems at combat-relevant ranges.

Enclosure materials: plastic is most vulnerable.

Pulse entry is the ability of unwanted EMS energy to penetrate the target and reach vulnerable electronics. Contributing factors include outer mold line construction material and vehicle shape. In general, materials specifically designed to shield against EMI are most effective against HPM entry, followed by metallic surfaces (which conduct and attenuate the pulse), with plastics and related materials most vulnerable to penetration.

Effect of shielding: measured in decibels attenuation (note: logarithmic unit).

For example, shielding that provides 20 dB of attenuation reduces EMI field strength to 0.1 times its original value, or a reduction of 90 percent. Assuming an initial field strength at the target of 15 kV/m, the widely accepted low-end damage threshold for electronics, a vehicle would need 38 dB of shielding to attenuate the field to an acceptable level of 200 V/m. At 25 kV/m, the point at which many robust electronics are damaged, the shielding requirement becomes 42 dB of attenuation.

Shielding levels that protect:

Most information on military aircraft shielding is close-hold in the US, partner nations, and adversaries alike. However, an interpolated value of 40-50 dB may be assumed to be a general standard across such systems, due to many militaries requiring manned airborne systems be hardened against EMP resulting from nuclear detonations. Such pulses are capable of generating field strengths in excess of 50 kV/m, which would drive a minimum attenuation requirement of 48 dB.[41] Incidentally, a 2004 study by Swedish scientists Bäckström and Lövstrand demonstrated that the 4th generation JAS-39 Gripen fighter aircraft is shielded to provide approximately 40 dB of attenuation.[42]

Protection levels given by shielding fabric:

US-based Conductive Composites has created a nickel-embedded non-woven material that provides from 41 to 72 dB of attenuation, depending on pulse characteristics. The material ranges from .0018 to .003 inches thick, weighs from .75 to 5.76 grams per square foot, with costs at or under $10 per square foot.[43] Another company, Glenair, has developed composite braided shielding for internal system component wrapping that is up to 80 percent lighter than traditional nickel/copper braids.[44]

Personal opinion:

• if a drone is expected to come across a microwave weapon, it better be optically or fiber optically controlled
• for entry level protection, its flight controller and motor controller ought be packaged in an enclosure that can be wrapped in conductive material
• if an aluminum radiator for the motor controller exits the shielding, it should be in firm contact (part of the shielding)
• it should not rely on GPS, and should not have an exposed GPS antenna
• its motor wires should also be wrapped in continuous conductive material
• all shielding elements should be grounded together