Application of Defected Ground Structure to Suppress Out-of-Band Harmonics for WLAN Microstrip Antenna

Abstract

An application of defected ground structure (DGS) to reduce out-of-band harmonics has been presented. A compact, proximity feed fractal slotted microstrip antenna for wireless local area network (WLAN) applications has been designed. The proposed 3rd iteration reduces antenna size by 43% as compared to rectangular conventional antenna and by introducing H shape DGS, the size of an antenna is further reduced by 3%. The DGS introduces stop band characteristics and suppresses higher harmonics, which are out of the band generated by 1st, 2nd, and 3rd iterations. H shape DGS is etched below the 50 Ω feed line and transmission coefficient parameters (S21) are obtained by CST Microwave Studio software. The values of equivalent L and C model have been extracted using a trial version of the diplexer filter design software. The stop band characteristic of the equivalent LC model also has been simulated by the Advance Digital System software, which gives almost the same response as compared to the simulation of CST Microwave Studio V. 12. The proposed antenna operates from 2.4 GHz to 2.49 GHz, which covers WLAN band and has a gain of 4.46 dB at 2.45 GHz resonance frequency.

Suppressing up to fourth harmonic of an ISM band microstrip patch antenna using compact defected ground structures

“…Since, stop band of single DGS covers up to third order harmonics. Therefore, the proposed single DGS unit can also be used to suppress 3 harmonics in the same way as it is investigated by introducing H‐shaped DGS to the proximity feed fractal slotted microstrip antenna in . In order to provide wider stop‐band another unit of identical DGS with optimized distance from the previous DGS is placed, as a result stop band is extended and it becomes 4.1–10.86 GHz with resonating frequency 6 GHz.…”

“…Some interesting works are already reported to suppress and control the higher harmonics without using extra filter circuits. Use of defected ground structure (DGS) beneath the feed line of the antenna, and use of U‐shaped slot on patch are studied. Using simple H‐shaped DGS a single harmonic is suppressed whereas 2 harmonics are suppressed by using 2 photonic bandgap (PBG) structures and the compact microstrip resonant cell, and combinations of 2 dimensional PBG and one dimensional DGS on the ground plane .…”

“…Two similar size compact partial ring DGS and dumbbell shaped stub attached with the microstrip line are used to reject all higher order modes up to third harmonic of the fundamental operating frequency. Also, up to third order harmonic rejection is investigated in by introducing H‐shaped DGS to the proximity feed fractal slotted microstrip antenna. More recently, the simulation results to suppress all higher order modes up to fourth harmonics using 2 I‐shaped DGS and an inverted L‐shaped stub with the feed line have been reported in .…”

Multiband and Miniaturized dual layer Antenna incorporated with FSS and DGS

“…The size reduction of 45% is achieved using fractal gasket carpet Antenna and than by placing spiral arms in the same further reduces the size to 50% and multiresonant frequencies is obtained in [9]. The suppression of harmonics and size reduction of 43% is achieved by using DGS [10] further size reduction of 50% and 90% of microstrip antenna is presented in [12,13] using DGS and slots. The multiband operation in microstrip antenna is shown in [14] and [15] by etching Pentagonal and skew F shaped on Ground plane.…”

Improved DGS parameter extraction method for the polarization purity of circularly polarized microstrip antenna

“…DGS is a single defect or a small number of periodic defects on the ground plane of a microstrip antenna, which intrigued interests in recent years due to its attractive features such as the band‐stop and slow wave effect . The DGS is explored for size reduction of the antenna , design approach for circular polarization , mutual coupling reduction in antenna arrays , elimination of scan blindness in antenna arrays , to suppress higher harmonic modes in antennas , to improve radiation property of an antenna , etc.…”