Antenna Radiation Pattern
Every antenna shapes the electromagnetic energy it radiates into a characteristic pattern — a spatial fingerprint determined by geometry and physics. A simple dipole radiates broadly; a Yagi focuses energy forward; a phased array can steer its beam electronically by shifting the phase between elements. Here you can explore these patterns and watch the electric field radiate outward in real time.
How it works
The polar plot on the left shows the radiation pattern — gain as a function of angle θ. For a half-wave dipole, the electric field pattern follows E(θ) = cos(½π cos θ) / sin θ. This creates the familiar figure-eight pattern with nulls along the antenna axis and maximum radiation broadside.
Phased arrays
A phased array combines multiple elements with controlled phase differences. The array factor AF = Σ ej(n·kd·cosθ + n·δ) multiplies the single-element pattern, creating constructive interference in a steerable beam direction. Adjusting the phase shift δ electronically steers the beam without physically moving the antenna.
Key formula
E(θ) = cos(½π cos θ) / sin θ — half-wave dipole pattern