Energy Fundamentals Part Two

Overview Means of detecting the target Sensing energy, emitted or reflected Energy forms propagate as traveling waves categorized by frequency and wavelength

RADAR What does RADAR stand for? RAdio Detection And Ranging

Characteristics of Waves Frequency (Hz) Period Wavelength Velocity Amplitude

Maxwell’s Theory What is Maxwell’s Theory? Time varying electric field will produce a time varying magnetic field, and vice versa.

Formation of Electric and Magnetic Fields around an Antenna E-line Mag field e- e- e- 1. Show Slide and show electrical and magnetic fields. 2. Point out that: - The magnetic field lines are at 90 degrees to the electrical fields lines. - The field strengths are greater at the center of the antenna and less at the ends. 3. Another good picture is fig. 2-9 on p.29 of text. Electric field | Magnetic Field | Direction of Propagation.

Polarization What is polarization? Direction of Propagation? 3 Types? Antenna direction for horizontal polarization?

Three Propagation Paths Reflection Refraction Diffraction Snell’s Law??? n1*Sin θ1=n2*Sin θ2

Three propagation types Ground Waves Sky Waves Space Waves Which is the highest frequency? Why does it have to be the highest frequency?

Factors Affecting RADAR Range Antenna Height Ducting Spreading Absorption Constructive vs Destructive Interference

Communications LOS vs. OTH Basic communications path