The purpose of this work is to miniaturize a rectangular patch antenna which resonates at 2.4 GHz. To achieve this, we present a new geometry of a pi-shaped slot with three annular rings as a Defected Ground Structure (DGS). DGS is a periodic etched structure or aperiodic sequence of configurations, and it has been used to switch the resonance frequency from starting value 13 GHz to an ending value at 2.4 GHz without any changes in the areas of the actual rectangular microstrip patch antenna (RMPA). The proposed antenna is structured on an FR-4 substrate with thickness 1.6 mm and permittivity 4.4. The general size of the ground plane is 34 × 34 mm 2 . Using the optimal position and dimension of the pi-shaped slot on the ground, the resonant frequency is reduced to 2.4 GHz, which signifies an 81.53% decrease. Proposed antennas with and without DGS are simulated by using High-Frequency Structure Simulator (HFSS) and Advanced Digital System (ADS) Agilent technology, fabricated, and measured for Wireless Local Area Network (WLAN) application.

The main intention to present this work is to miniaturize and gain enhancement of a tapered microstrip patch antenna, which resonates for Global Positioning System (GPS) of L1 band at 1.575 GHz. To accomplish this, we present a new design configuration of a Tap-Shaped Defected Ground Structure (TSDGS). It has been utilized to switch the resonant frequency from 14.5 GHz to 1.575 GHz with no adjustment of areas of the actual Tapered Microstrip Patch Antenna (TMPA). The prototype antenna is fabricated on a Roger RT Duroid substrate merely 58 × 22 mm 2. Conclusively, a miniaturization allowed up to 89.31%, with regard to the TMPA, is excellently accomplished. The gain of the proposed antenna is successfully enhanced with properly locating the metamaterial superstrate onto the basic patch antenna. A gain of 7 dBi improvement has been achieved. The proposed design process is done with two different solvers, ADS and HFSS.

In this article, a miniaturized antenna with a Koch fractal defected ground structure (KFDGS) is proposed for C/X and Ku-band applications. The performance of an inset-fed lambda/2 patch antenna is examined using an iterated KFDGS etched on the ground plane. A conventional antenna operated at 16 GHz with a return loss of −34.31 dB is constructed, followed by a tri-band miniaturized antenna operating at 6.35, 9, and 13.05 GHz with a return loss of −22.41, −25.05, and −28.54 dB in order to achieve miniaturization of 60.31%, 43.75%, and 18.43%, respectively. An antenna is designed on a Roger RT Duroid substrate, fabricated, and tested with dimensions of 12×14×0.8 mm 3 , and its impact on reduction in size performance has been evaluated with measured peak directivity and gain of 3.07 and 2.80 dBi at 6.35 GHz, 4.78 and 4.65 dBi at 9 GHz, and 7.73 and 7.76 dBi at 13.05 GHz, respectively. A good agreement is found between the measurements and simulations.

In this article, a miniaturized pentagonal slot antenna (PSA) with a Meander Koch Defected Ground Structures (MK-DGS) and metamaterials (MTM) is proposed for 5 GHz WLAN application. Initially, a Meander Koch DGS was used to lower the resonant frequency of the basic PSA, from 13.1 GHz to 5 GHz. The proposed antenna has been 61.83% miniaturized, close to an electrically small antenna. The performance characteristics of a basic PSA using MK-DGS and MTM superstrate, which improves efficiency, directivity, and peak gain, are also discussed. An antenna with dimensions of 15×15 mm 2 (or) 0.25λ 0 × 0.25λ 0 mm 2 at a thickness of h 1 = 1.6 mm is designed, fabricated, and tested on an FR4 epoxy substrate, and its impact on size reduction performance is evaluated. The gain at 5 GHz is increased from 3.15 to 7.84 dBi by introducing an MTM superstrate made of RT Duriod at a thickness of 1.575 mm above the miniaturized PSA at 17 mm. Test results of the prototype model are corroborated by the simulated results of the proposed model.