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Dipolo Infinitesimal. Sandra Cruz-Pol, Ph. D. INEL 5305 ECE UPRM Mayagüez, PR. Outline. Maxwell’s equations Wave equations for A and for F Power: Poynting Vector Dipole antenna. Maxwell Equations. Ampere:. Faraday:. Gauss:. Relaciones de Continuidad. Potencial Magnético Vectorial A.
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Dipolo Infinitesimal Sandra Cruz-Pol, Ph. D. INEL 5305 ECE UPRM Mayagüez, PR
Outline • Maxwell’s equations • Wave equations for A and for F • Power: Poynting Vector • Dipole antenna
Maxwell Equations Ampere: Faraday: Gauss:
Potencial Magnético Vectorial A • Si lo sustituimos en la Ley de Faraday: F is the Electric Scalar Potential
Lorentz’ condition • Si escogemos • Queda la Ecuacion de Onda donde J es la densidad de una fuente de corriente, si hay.
Wave equation • For sinusoidal fields (harmonics): where
Outline • Maxwell’s equations • Wave equations for A and for F • Power: Poynting Vector • Dipole antenna
Average S Para medios sin pérdidas:
Outline • Maxwell’s equations • Wave equations for A and for F • Power: Poynting Vector • Infinitesimal Dipole antenna
Find A from Dipole with current J • Line charge w/uniform charge density, rL Assume the simplest solution Az(r): z Az r r q Jz x 0
To find…. Assume the simplest solution Az(r):
Fuera de la Fuente (J=0) Which has general solution of:
Apply B.C. • If radiated wave travels outwards from the source: • To find C2, let’s examine what happens near the source. (in that case k tends to 0) • So the wave equation reduces to
Now we integrate the volume around the dipole: • And using the Divergence Theorem
Now from A we can find E & H • Using the Victoria IDENTITY: • And • Substitute:
General @Far field r> 2D2/l Note that the ratio of E/H is the intrinsic impedance of the medium.
Resistencia de Radiacion • La potencia tiene parte real y parte reactiva • La potencia irradiada es: • Comparando con la P total, se halla la Impedancia • COmparando cno la Prad, halla la Rrad.