The History of Radar | Radar History: Isle of Wight Radar During The Second World War | Radar: The Basic Principle
Radar Technology: Main Components | Radar Technology: Side Lobe Suppression | Radar Technology: Airborne Collision Avoidance
Radar Technology: Antennas | Radar Technology: Antenna Beam Shapes | Radar Technology: Monopulse Antennas | Radar Technology: Phased Array Antennas | Radar Technology: Continuous Wave Radar | Theoretical Basics: The Radar Equation
Theoretical Basics: Ambiguous Measurements | Theoretical Basics: Signals and Range Resolution
Theoretical Basics: Ambiguity And The Influence of PRFs | Theoretical Basics: Signal Processing | Civilian Radars: Police Radar | Civilian Radars: Automotive Radar | Civilian Radars: Primary and Secondary Radar
Civilian Radars: Synthetic Aperture Radar (SAR) | Military Applications: Overview | Military Radars: Over The Horizon (OTH) Radar
How a Bat's Sensor Works | Low Probability of Intercept (LPI) Radar | Electronic Combat: Overview | Electronic Combat in Wildlife
Radar Countermeasures: Range Gate Pull-Off | Radar Countermeasures: Inverse Gain Jamming | Advanced Electronic Countermeasures

There aren't any animal species that have been known to use radio frequencies or microwaves for any purpose. However, light is just another part of the electromagnetic spectrum and is subject to the same physical laws, and there are animals using light for deception and combat, employing them in tactics quite similar to those of modern electronic combat. Sound may be completely different in its physical nature, but its properties for communication and echo location can be exploited in similar ways.

Sound

The ultrasonic sensor of a bat is the grandmother of all radars. Bats emit a short 'cry' from out of their noses, and receive the echo with a set of two antennae which happen to be ears. A bat's radar doesn't use electromagnetic rays, but the working principle is the same as that of a modern radar. The entry How a Bat's Sensor Works has more details about that.

Tiger moths have developed ears that can detect bats' signals and trigger a series of clicking noises that jam the bat's detector. This is precisely what self-protection jammers do.

Electric Fields

Some electric fish create an electric field around themselves which is used to detect and communicate with other fish. Some also have invented frequency-hopping as a means to avoid jamming. See here for more details.

Light

In the depth of an ocean there is almost, but not entirely, complete darkness. Only traces of sunlight can be detected down there. You wouldn't expect anything exciting. However, the depths of an ocean are the habitats of some real electronic combat experts.

• There are a few predators like the large hatchetfish (argyropelecus gigas) that take advantage of the minimal illumination by looking upwards and waiting for the shadow of some other animal swimming by. Evolution of prey animals has found a countermeasure: some fish and cephalopods exhibit bioluminescence. Their skin is able to emit just about the right amount of light to compensate their own shadow and thus they render themselves indetectable. Most notable examples are chiroteuthis and galiteuthis who both take care that whatever side of their body is facing downward is the side that emits the camouflaging luminescense. The word stealth technology springs to mind.

• Other animals have developed chromatophores - this means that they can adapt the colours and texture of their skin such that it perfectly matches the structure of their hiding places. This is camouflage in perfection.

• Some species produce sticky and luminescent mucus when put under stress from an attacker. This slime adheres to the predator and makes it a well-distinguishable target for its own enemies further up the food chain. This is what target illumination is all about.

• Anglerfish feature a luminiscent appendix (ilicium) to their lower chin. This appendix is used as bait for other predators while the anglerfish is lying in ambush. A radar decoy transmitter is something not completely different from that.

• Glass worms of the tomopteridae family produce a sort of liquor that contains hundreds and thousands of luminiscent particles when under pursuit from a predator. In similar fashion, the jelly colobenema is able to jettison some of its twinkling tentacles and escape, mostly unharmed. These particles serve to confuse the predator's senses just like chaff that is jettisoned from modern aircraft to confuse a hostile radar or missile seeker-head.

Conclusion

In conclusion, it is only appropriate to credit nature itself for having invented electronic combat.

History: Overview | Isle of Wight Radar During WWII
Technology: Basic Principle | Main Components | Signal Processing | Antennae | Side Lobe Suppression | Phased Array Antennae | Antenna Beam Shapes | Monopulse Antennae | Continuous Wave Radar
Theoretical Basics: The Radar Equation | Ambiguous Measurements | Signals and Range Resolution | Ambiguity and PRFs
Civilian Applications: Police Radar | Automotive Radar | Primary and Secondary Radar | Airborne Collision Avoidance | Synthetic Aperture Radar
Military Applications: Overview | Over The Horizon | Low Probability of Intercept | How a Bat's Sensor Works
Electronic Combat: Overview | Electronic Combat in Wildlife | Range Gate Pull-Off | Inverse Gain Jamming | Advanced ECM | How Stealth Works | Stealth Aircraft