Design of a radiated-mode multislot leaky coaxial cable

In this paper, we propose a closed-form equation and a novel design procedure for suppressing the space harmonics and coupling loss of a radiated-mode leaky coaxial cable (LCX). The LCX with periodic principal slots is analyzed using Floquet theory, and its radiation usually contains higher radiation harmonics that may cause an uneven coupling loss. A closed-form equation is derived to determine the orders of the harmonics being suppressed. Consideration of the resonant points makes it possible to choose the operating-frequency range of the antenna from the passband region, where the level of the resonant points is low. The proposed design procedure, which leads to the suppression of the higher radiation harmonics and longitudinal loss, features the use of additional slots with unequal pitches. A sample LCX antenna is designed, fabricated, and tested at 1800 MHz using the proposed procedure. The measurement results for the coupling loss agree well with the simulation results. (c) 2005 Wiley Periodicals, Inc.