I have tried to design a third iterated Sierpinski Gasket fractal antenna of a standard 88.9 mm height for multiband operation. This antenna resonates at 0.52 GHz, 1.752 GHz, 3.712 GHz and 6.968 GHz for a coaxial feeding case. The waveguide port extension coefficient for operation in frequency range of 0 to 8 GHz for a microstrip line width of 4.542 mm, a substrate height of 1.588 mm and relative permittivity of 2.5 was required to be in the range of 4.85 to 8.39. This range of waveguide port extension coefficient could provide antenna resonance at the above frequencies with improved impedance matching by using a microstrip line feed that had a quarter wavelength at the lowest frequency (0.52 GHz). However, to avoid larger antenna length, i used a microstrip line length of quarter wavelength at the largest frequency (6.968 GHz). By using such a short length of microstrip line, fundamental frequency got shifted from 0.52 GHz to 0.394 GHz. To make the antenna resonate at the same fundamental frequency (0.52 GHz), I had to increase the port extension coefficient from the range 4.85 -8.39 to 39-42. Is it valid to use such large port coefficients? Why do resonant frequencies (particularly the fundamental design frequency) change with port extension coefficient? More importantly are such large ports physically realizable?
Dear Deepanshu Kaushal ,
I believe the attached articles and their references will help you to answer these questions.
Dear Deepanshu Kaushal ,
I believe the attached articles and their references will help you to answer these questions.
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