Introduction to Antenna Theory - RAHAE102

Explore the radiation characteristics of a linear thin dipole, including its radiation field, pattern, input impedance, and polarization for a wire length comparable to the wavelength.

Explore the radiation characteristics of a center-fed linear thin dipole, also described as a diabolo antenna, with two halves and center excitation driving current along the element.

Explore current distribution on a dipole antenna by modeling it as infinitesimal current elements, apply superposition to obtain the far-field radiation pattern, and understand phase relations with distance.

Analyze the current distribution on a dipole from the standing wave pattern, with zero current at the ends, and derive the far-field by summing theta-directed fields from infinitesimal current elements.

Derive the far-field electric field of a current element and its radiation pattern, relating the electric and magnetic fields via intrinsic impedance to describe dipole radiation.

Calculate the electric field and derive the normalized radiation pattern and input impedance of the antenna, showing how the field amplitude varies with angle and distance.

Analyze how dipole input impedance varies with length and current distribution, and how the radiation pattern shows nulls and maxima in various directions, with wavelength effects shaping the pattern.

Explore the dipole antenna radiation pattern by locating nulls and main lobes, using sign choices to identify directions of maximum radiation and related angles.

Explain how Maxwell's equations govern free-space electromagnetic wave propagation, covering Ampere's law, Faraday's law, and the displacement current at high frequencies, with J equal to sigma E.

Derive the wave equation for the electric field in free space from Maxwell's equations in a homogeneous medium, leading to the Cartesian form.

Verify wave equations in free space via the electric displacement field and E, B relations; derive the wave speed v = 1/√(μ0 ε0) with μ0 and ε0 values.

Explains how energy flows in electromagnetic fields using the Poynting vector, derived from Maxwell's equations, and how volume and surface integrals describe power dissipation, storage, and outflow.

Compute the phase constant, wavelength, and angular frequency for a linearly polarized EM wave in free space at one gigahertz, and determine the electric field amplitude of a uniform plane wave.

Analyze how a receiving antenna converts incident electromagnetic waves into voltages and currents, determines received power, and relates transmit and receive properties through reciprocity and polarization.

Examine how a dipole antenna at the receiver side converts incident plane waves into open-circuit voltage, revealing angle-dependent polarization effects and the sin theta receiving pattern.

Explore the effective aperture, reciprocity between transmitting and receiving, and how maximum power occurs with a complex conjugate match to the load.

Define the effective aperture as the ratio of load power to incident wave's power density, the pointing vector, illustrating that it may differ from the receiving antenna's physical area.

Explore the liaison between effective aperture and directivity, showing how a larger parabolic antenna increases effective area and the coupling between transmitting and receiving antennas via mutual impedance and reciprocity.

Derive the received power at the antenna by relating transmitted power to current and mutual impedance, using the complex-conjugate, and relate power density to distance.

Examine interchanging the roles of receiving and transmitting antennas, showing that the effective aperture and received power are directly related and, for both configurations, independent of the field.

explains the general relation between directivity and effective aperture, showing how antenna gain relates to beam width and effective aperture and applying this to parabolic antennas.

Compute the average energy density and average power for a circular area in free space using complex form and complex conjugates.

Apply the method of images to a charge near an ideal ground plane, replacing the plane with an image charge and matching field and current directions across the boundary.

Explain why monopole antennas are used for low frequency broadcasting, including ground-plane symmetry, terminal impedance, lambda/4 and lambda/2 length relations, and the resulting radiation pattern.

Calculate the radiated power of a dipole antenna by integrating the fields and using the radiation resistance, yielding about 73 ohms for a half-wave dipole.

Explore dipole antenna parameters, including current distribution and symmetry, and learn how to determine half-wavelength spacing and radiation characteristics for practical gain estimates.

The current distribution on an aperture determines the radiation pattern; integrating the field of a small current element reveals the pattern as the Fourier transform of the current.

Solve numerical problems on dipole antennas, demonstrating that isotropic activity is unity and deriving the maximum effective aperture for a dipole type under an incident plane wave.

Practice solving an antenna theory quiz on monopole and dipole calculations, including radius, distance, radiated power, field strength, and efficiency for free-space and near-earth scenarios.

Practice solving antenna theory problems, including current element distance, lambda-based calculations, power radiated by a lambda/16 dipole in free space, and electric field intensity and radiated power density.

Calculate power, resistance, and effective length for a transmuting antenna using frequency and wavelength, with distance-based considerations. Compare isotropic and dipole models and assess efficiency.

Calculate antenna efficiency and radiated power from the given values, including wavelength, impedance, and distance, as explored in the quiz solution.

Continue quiz solutions by applying complex form, intrinsic impedance, and the average pointing vector to relate electric field components and their conjugates, then compute monopole power and efficiency.

This quiz solution continues solving for input power, efficiency, and transmitting power in a low-frequency antenna setup, detailing impedance calculations, effective length, and radiation distance.

Explore how antenna arrays combine multiple antennas to create constructive interference and narrow beams, boosting radiation performance while preserving terminal impedance, with linear arrays and equal spacing.

Learn about broadside arrays with equal-amplitude, in-phase elements spaced along a line perpendicular to the axis, producing bidirectional radiation, and end-fire arrays with phase differences to steer a unidirectional pattern.

collinear arrays place antennas in a single line to maximize radiation perpendicular to the axis, with in-phase feeding of two to four elements yielding about 2–4 dB gains.

Explore how parasitic elements couple with a driven element to shape a unidirectional rotation pattern, using reflectors and directors to optimize front-to-back ratio across 100–2000 MHz.

Analyze the radiation from two isotropic point sources with equal amplitude and phase, derive the far-field interference, and show a bidirectional figure-eight pattern with max and Hofbauer points.

Explore the far-field pattern of two point sources with equal amplitude and opposite phase, yielding a doughnut-shaped two-dimensional radiation pattern and the related vector sum.

Analyze far-field pattern of two isotropic point sources with equal amplitude and opposite phase, and derive total field via vector addition and phase difference, expressed with cosine and sine.

Explore non isotropic but similar point sources, examining how equal-amplitude sources form symmetrical patterns through superposition and pattern multiplication, with dipole configurations and cosine relations.

Learn how multiplying the pattern of individual sources by the array’s isotropic pattern yields the total radiation pattern, including phase and amplitude effects, for two-dimensional and three-dimensional antenna arrays.

Demonstrates obtaining the radiation pattern of four isotropic elements in phase, spaced lambda/2 apart, using pattern multiplication with two-element units and equal amplitude, producing an eight-shaped bidirectional pattern.

Introduction to an array of n isotropic sources with equal amplitude and spacing in broadside configuration, deriving beam direction expressions using wavelength, element spacing, and total array length.

Explore an array of n isotropic sources with equal amplitude and spacing in the endfire case, deriving the direction of the maximum and the influence of alpha and lambda.

Explore end-fire arrays of n isotropic sources with equal amplitude and spacing, applying Henshilwood conditions to optimize phase differences for maximum radiation along 180 degrees while preserving array characteristics.

explains binomial arrays by arranging radiating source amplitudes according to binomial series to suppress secondary lobes, with center sources stronger than edge sources and specific spacing conditions.

Explore continued Chebyshev arrays by solving cosine relationships for X, deriving M minus one cos X equals zero, and applying the resulting expressions to antenna design.

Engage in numerical practice for antenna arrays, deriving two-element and multi-element patterns, optimizing spacing, phase, and current amplitudes to achieve a central maximum.

Continue numerical design of a seven-element antenna array using Laguerre to solve for X0. Determine current and relative amplitudes and broadside activity with exponential and hyperbolic relations.

Continue numerical practice on isotropic in-phase sources with lambda spacing, solving for a linear 10-element arrangement and examining how spacing affects the activity.

Continue numerical practice in antenna theory by solving integration-based problems, deriving maximum values, and evaluating efficiency and the effective aperture for spaced antennas.