Leaky characteristics of modified suspended substrate microstrip line with multilayer dielectric structure

A modified suspended substrate microstrip line with multilayer dielectric structure is proposed, and the leaky characteristics of the antenna structure are theoretically investigated. It is demonstrated that a suitable choice of the dimension of the structure can guarantee the antenna working in the antenna-mode region to make the antenna operate in an efficient way. Besides, very flat variation of the leakage constant with frequency can be achieved by appropriate choice of the structure parameters. It is a desirable property for practical use as a frequency scanning antenna since it ensures a stable radiation pattern with little distortions as the beam is being scanned.