Weps Midterm 2026

Fire Control

3 Phases

• Detection

• Tracking

• Engagement

Detect to Engage - Phase 1

Detection

• Detect

  • target, environment (noise)

• Localize

  • speed, bearing, elevation, range, depth

• Classify

  • number, size, ID, type

Detect to Engage - Phase 2

Tracking → fire control solution

• generate continuous target data

• feedback loop with localization

Detect to Engage - Phase 3

fire control solution → Engagement

• weapon selection

  • launching, propulsion, guidance, control weapon

• neutralization

  • fuzing

  • warhead

  • effects

Mechanical vs Electromagnetic Wave

Mechanical

• requires a medium for propagation

• ex. sonar

Electromagnetic

• doesn’t require a medium for propagation

• ex. RADAR, visible light, thermal radiation

4 Types of Wave Propagation

Reflection

• specular (equal but opposite angle off smooth surface)

• diffuse (waves strike uneven surface, reflect at many angles)

Refraction

• not all EM wave is reflected, some refracted and bent into the other medium

• angle determined by Snell’s law and the refractive index

Diffraction

• EM waves diffract around objects (land mass, mountain top, slit, etc.)

• can detect signals despite LOS limitations

Interference

• constructive interference (two identical waves create one bigger wave)

• destructive interference (two opposite waves cancel each other out)

Attenuation (definition and types)

Attenuation - EM signal loss

Spreading

• energy distributed over an increasingly larger area

Absorption

• energy dissipated into a medium

Scattering

• energy bounces off suspended particles within a medium

note: attenuation increases as frequency increases

Modes of Wave Propagation

Ground Waves

• follow curvature of the earth, form a duct between ground and ionosphere

• lowest frequency

Sky Waves

• bounce off ionosphere back to earth or travel in the ionosphere

• medium frequency

Space Waves

• penetrate ionosphere and travel through space

• highest frequency

Beamforming and Directionality

Directionality allows more efficient energy use

• achieved by using reflectors

Two Reflector Types

• Parabolic

  • reflective beamforming (energy bounces off a cone in one direction)

• Parasitic

  • cancellation beamforming (driven element induces parasitic voltage which produces constructive and destructive interference which gives directionality)

Search vs Targeting Radar

Different Radar beamwidths

Search: wide beamwidth

• looking to see if something is there

Targeting: narrow beamwidth

• used for fire control (launching missiles)

MSA vs. ESA

MSA: mechanically steered array

• have to physically move (slower)

• require more power, slower response time

ESA: electronically steered array, aka Phased Array

• uses ionized air/phase shift to create and send out a beam

• instantaneous, less moving parts to break

• increased flexibility

  • multi-target tracking

  • multi-mode ops (frequencies) - search or fire control

Continuous Wave Radar (CW)

CW

• continuously transmits and receives

• requires relative motion to determine target presence (either target or radar movement)

• requires 2 antennas (one to transmit, one to receive)

  • uses a mixer to distinguish between transmitted and received frequencies

• can only measure velocity, not distance

Basic Pulsed Radar

Pulsed

• transmits short pulses followed by long rest periods where range is determined based on pulse return time

• target is detectable while stationary or moving at same speed & bearing

• requires only one antenna

Frequency Modulated Continuous Wave Radar

FMCW

• frequency increases over time, time stamp created for transmitted signal → cycle repeats constantly

• transmitted and received signal’s frequencies compared

  • difference in frequencies gives a time of travel, time of travel gives range

  • doppler gives velocity

• commonly used as radar altimeters, short range proximity detectors

SAR and ISAR

SAR - synthetic aperture radar

• radar on moving platform focuses on target of interest

• system stores returns as platform moves and creates “synthetic aperture” image of target

• advantages: large effective aperture, outstanding resolution

• disadvantages: large storage capacity and computer power needed (not as relevant as technology advances)

ISAR - inverse SAR

• if target has periodic motion (yaw, pitch, roll), then SAR image can be achieved without a moving radar

Guidance - Detect to Engage

Boost

• from when weapon receives launch signal to when weapon is in stable flight toward target

Midcourse

• inputs may be required to bring missile on course and stay there (longest phase in distance and time)

Terminal

• high accuracy, fast response to target’s evasive maneuvers