Introduction Flashcards
RF engineering
designing systems and components to relay information and/or power from one location to another via electromagnetic waves as efficiently as possible
Electromagnetic wave
a disturbance that transmits energy from one location in space to another
Solution to fundamental wave equation
forward-travelling wave and reverse-travelling wave
Gradient
returns a vector that has the rate and direction of maximum ascent. ( ∇A)
Divergence
How much a vector spreads out from a point (∇ ⋅ A)
Solenoidal
When the divergence is 0, the field is solenoidal and always forms closed loops
Curl
returns a vector telling us how much the field circulates about a point, with the direction dictated by the RHR. (∇ x A)
Faraday’s Law
E-fields circulate around points of time-varying magnetic field.
Gauss’ Law
Electric flux density spreads out from point of non-zero free charge density. (∇ ⋅ D) = ρ
Ampere’s Law with Maxwell’s addition
Magnetic field intensity (H) circulates around points of non-zero conduction current density (J) and displacement current density (dD/dt)
The speed of an EM wave in a medium
is equal to the speed of light in that medium
A vector with a curl of zero is
irrotational/conservative
Equation for the D-field
D = ε0E+P, where P is the polarization vector
Permeability
μ,the ability of the material to form an internal magnetic field within itself under the influence of an applied magnetic field
Permittivity
a measure of the electric polarizability of a dielectric
Conductivity
Electrical conductivity (or specific conductance) is the reciprocal of electrical resistivity. It represents a material’s ability to conduct electric current
Equation for the B-field
(1/μ0)H-M, where M is the magnetization vector
B-fields are always
solenoidal
Linear Medium
Medium properties are independent of the intensity of the applied fields
Isotropic Medium
Medium properties are independent of the orientation of the applied fields
Homogeneous Medium
Medium properties are independent of spatial variables (x,y,z)
Curl of the gradient is
always zero
Divergence of the curl is
always zero
Magnetic Potential Vector
B = ∇ x A
Magnetic Potential Vector with Faraday’s Law
∇ x (E + dA/dt) = 0 (always). This is used to define the electric scalar potential
Electric Scalar Potential
E + dA/dt = -∇V
Assumptions made for linear, isotropic and homogenous mediums
Allows us to simplify maxwells equations and express in terms of E and H(orB)
Time Harmonic Excitation assumptions
excitation is periodic, allows for phasor/Fourier analysis (frequency domain) d/dt -> jw for Maxwell’s equations
Lossless medium
A lossless medium is a medium with zero conductivity and finite permeability and permittivity
