DefinePK

Abstract

This paper presents a tapered baluns of microstrip-to-parallel strip transition using triangular structure with linear transition that suitable for a 3-dimensional (3-D) harmonic suppressed dipole antenna (3D-HSDA). The original balun consists of linear profile with the size of a quarter-wavelength for both the height and width with broadband characteristic (from 0 to 7 GHz). However, for some application such as narrowband HSA design, the suppression of the high operating band is needed. By using three open circuit stubs and three rectangular element of defected ground structure (DGS), two tapered baluns have been produced having the stop band feature from 2.1 GHz to 7 GHz of frequencies. They are named as balun-stubs and balun-DGS, respectively, that operate from 0 to 2 GHz. Simulated and measured results based on the return loss and insertion loss for these baluns were found to be better than -10 dB and -3 dB, respectively, from 0 to 2 GHz. The employment of the stubs and the DGS made these baluns the capability to reject the unwanted high frequency band. At last, these balun are integrated with dipole antenna for validation purpose. The results shows the antenna with balun-stubs and antenna with balun-DGS operates at 900 MHz and removed undesired higher order modes at 2.75 GHz, 4.47 GHz and 6.2 GHz without affecting the operating frequency.