The divergence theorem, also known as Gauss's theorem, relates the flux of a vector field through a closed surface to the divergence of the field within the volume enclosed by the surface. It is fundamental in converting volume integrals to surface integrals and is used extensively in deriving and applying Maxwell's equations.
Electromagnetic wave propagation refers to the way electromagnetic waves travel through different mediums. These waves are solutions to Maxwell's equations and propagate through the oscillation of electric and magnetic fields, perpendicular to each other and the direction of wave travel.
The Poynting vector S represents the power per unit area carried by an electromagnetic wave. It is given by = × S=E ×H, where E is the electric field and H is the magnetic field. The Poynting vector indicates the direction of energy propagation and the magnitude of power flow in an electromagnetic field.
The superposition theorem states that in any linear circuit with multiple independent sources, the current and voltage for any element in the circuit is the algebraic sum of the currents and voltages produced by each source acting independently.
An electric field � E is a field around a charged particle that exerts a force on other charged particles. A magnetic field � B is a field around a magnetic material or a moving electric charge that exerts a force on other moving charges or magnetic materials. Electric fields originate from charges and are described by Coulomb’s law, while magnetic fields originate from moving charges (currents) and are described by Biot-Savart and Ampère’s laws.
Boundary conditions in electromagnetics determine how electric and magnetic fields behave at the interface between different media. They are essential for solving Maxwell's equations in practical scenarios, ensuring continuity of the tangential component of the electric field and the normal component of the magnetic flux density across the boundary.
Polarization of an electromagnetic wave refers to the orientation of the electric field vector as the wave propagates. It can be linear, circular, or elliptical. Linear polarization means the electric field oscillates in a single direction, circular polarization means it rotates in a circle, and elliptical polarization is a general case where the electric field traces out an ellipse.
Common types of transmission lines include:
The Smith chart is a graphical tool used for solving problems with transmission lines and matching circuits. It represents complex reflection coefficients and impedance. It is used to visualize impedance transformations, solve impedance matching problems, and analyze S-parameters
Antenna gain is a measure of how well an antenna directs or concentrates radio frequency energy in a particular direction compared to an isotropic radiator. It is usually expressed in dBi (decibels over isotropic) and can be measured using methods such as the far-field measurement technique.