Approximation technique for determining gain and radiation pattern of the horn antenna

It is shown that an approximation can be used to avoid the complex mathematics and computation methods for calculating the gain and radiation pattern of the electromagnetic horn antenna. Because of the curvature of the antenna wave front, calculations using conventional techniques typically involve solving the Fresnel integrals and using computer-aided numerical integration. With the proposed model, linear approximations give a reasonable estimate of the gain and radiation pattern using simple trigonometric functions, allowing a hand calculator to replace the computer. The case of the E-plane horn antenna was used to evaluate this technique, applying selected criteria. Results showed that the gain approximation holds for an antenna flare angle of less than 10° for typical antenna dimensions, and the E-field radiation pattern approximation holds until the antenna´s phase error approaches 60°, both within typical design parameters