CRLH unit cell loaded quad-band monopole antenna

A novel design of quad-band monopole planar antenna has been presented in this letter. Initially, a dual-band monopole antenna is excited at two distinct frequencies using monopoles of two different lengths in the same design. Furthermore, the longer monopole with lower operating frequency is loaded with composite right/left handed (CRLH) unit cell, due to which two additional operating narrowband frequencies are obtained. The special characteristic of the CRLH unit cell lies in the design trick of the meandered stub inductor, a significant length of which is adjusted by doubly folding it within a smaller area leading to an electrically smaller unit cell size. The resonant frequencies of the fabricated quad-band antenna are found at 0.85, 1.61, 2.42, and 3.55 GHz. The prototype of the proposed antenna is fabricated and measured. The measured results are in good agreement with the simulated results. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:653-658, 2016