Heliyon (Mar 2021)
A novel quadband ultra miniaturized planar antenna with metallic vias and defected ground structure for portable devices
Abstract
A novel heart-shaped monopole antenna used in wireless portable communication devices is proposed and discussed in this paper. The antenna has a radiant patch surface area of 28.504 mm2, the physical size of 15 × 12.5 × 1 mm3, and electrical dimensions of 0.095λ0 × 0.079λ0 × 0.006λ0, where λ0 denotes the wavelength of the free space at 1.89 GHz. Its prototype is printed on FR4 HTG-175, having a permittivity of 4.2 and a loss tangent of 0.019 at 1 GHz. The partial ground plane and two metallic vias connecting two open-ended branches of the slitted radiating patch to a parasitic conductor element results in about 98% miniaturization of the active patch area, as compared to the conventional antenna. The proposed antenna exhibits nearly an omnidirectional pattern in the elevation plane with a maximum radiation efficiency of 82.78% at 3.99 GHz, while a peak gain of 4.7 dBi is obtained at 6.5 GHz. The measured -6 dB impedance bandwidths demonstrate that the proposed quadband antenna operates in all the frequency bands of mobile telecommunication standards (2G/3G/4G/5G) and other applications, including WLAN, WiMAX, ISM, meteorological services, IEEE 802.11y, and C-band satellite communications. This antenna is easy to manufacture and can be used in most portable devices as a compact internal antenna. After simulating the modeled antenna using HFSS, a prototype was experimentally tested, and the measured results were compared with the data obtained by simulation. The parameters analyzed are return loss, bandwidth, and gain on all frequency bands. The fabricated prototype guarantees a minimum -10 dB bandwidth of 110 MHz and a maximum return loss of -12.2 dB, despite its low radiation efficiency of 21.43 % in the lower band dedicated to GSM applications. Furthermore, the proposed antenna operates as a narrowband and wideband.
