Diverging/focusing of electromagnetic waves by utilizing the curved leakywave structure: application to broad-beam antenna for radiating within specified wide-angle

A new "broad-beam antenna" for radiating electromagnetic energy in a specified wide angular region is proposed, utilizing the "curved leakywave structure". This structure consists of the leakywave structure curved physically and longitudinally into the form of an equi-angular spiral. The expression of the radiation field from this structure is given, the effects of various geometrical parameters on the radiation properties is discussed numerically for the design of the broad-beam antennas, and a simple experiment is also performed to verify the beam broadening by the proposed method. The concept in this paper may be easily applied to any leakywave structure such as a periodic dielectric antenna and a leaky nonradiative dielectric (NRD)-guide antenna for millimeter-wave application.