An approach for design of size independent simple microstrip antenna with complementary split ring resonator at ground plane

Microstrip antennas have received a wide attention all over the world in the past few decades with the fast development of portable electronic gadgets like mobile phones, laptops etc. The sizes of these devices are shrinking day by day and functionalities are becoming wider. However, the size of the microstrip antenna often puts a limit to the extent to which the size of a device can be. Half-wavelength and quarter-wavelength antennas are considered as standard in many theoretical works. In some recent works some fractional wavelength antennas with electrical size reduced up to only a small fraction of wavelength have been proposed. In this work, a new approach has been presented that attempts to eliminate the convention of considering operating frequency as a limiting condition for design of microstrip antenna and provides the freedom of selecting a considerably small antenna irrespective of operating frequency. The key feature of the antenna is a Complementary Split Ring Resonator (CSRR) which is used at the ground plane. By adjusting the various dimensions of the CSRR structure resonant frequency at different frequencies can be obtained. In this way the electrical size of a stripline fed rectangular antenna is reduced up to only 12.9% of resonant wavelength.