Q1Electromagnetics Waves

A monopole antenna is a single straight radiating element, typically a quarter-wavelength (λ/4) long, mounted perpendicular to and fed against a conducting ground plane; by image theory the ground plane creates a virtual mirror-image of the monopole below the plane, so the monopole-plus-image combination behaves electrically like a full half-wave dipole, but radiates only into the hemisphere above the ground plane. A dipole antenna is two collinear conducting arms (commonly each λ/4 long, for a total length λ/2) fed at the small central gap between them, requiring no ground plane since it is a self-contained, balanced radiator; it radiates into all of free space except along its own axis, producing the characteristic doughnut-shaped pattern. Both are linear-wire radiators and share closely related radiation-resistance and pattern properties (the monopole's radiation resistance is exactly half the dipole's, as derived in Part C, Q.4 of the companion 2024 Jan/Feb paper on this subject), differing mainly in whether a ground plane is used to create the image half of the equivalent radiating structure.