Miniaturized Dual-Band Dual-Mode Microstrip Patch Antenna with Defected Ground Structure for Wearable Applications

This work presents the performance of a miniaturized dual-band dual-mode microstrip patch antenna with Defected Ground Structure (DGS) at 2.45 GHz and 5.8 GHz on the stacked substrate configuration in the order of FR-4 – PDMS- FR-4. The antenna offers a promising solution for wearable applications in the ISM bands. The first substrate is a flexible Flame Retardant 4 (FR-4) and the other substrate is a highly flexible Polydimethyl Siloxane (PDMS). The size of the antenna was reduced from 50 × 50 mm2 to 30 × 30 mm2, by introducing DGS on the ground plane. A single U-slot on the rectangular radiating patch was introduced to produce the upper resonant frequency of 5.8 GHz while the existing square patch is to generate the lower resonant frequency of 2.45 GHz. The simulations on the dual-band dual-mode microstrip patch antenna shows the reflection coefficient, S11 at 2.45 GHz is -17.848 dB with a bandwidth of 278.8 MHz and -13.779 dB with a bandwidth of 273 MHz at 5.8 GHz. A unidirectional radiation pattern observed in the E-plane shows that the antenna could be applied for off-body communication while an omnidirectional radiation pattern in the H-plane showed that the antenna can be used for on-body communication. Bending investigation were performed for the antenna over a vacuum cylinder with varying diameters of 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm and 120 mm in the CST MWS® software. From the graph of reflection coefficients, the performance of the antenna were not affected in bending condition. The SAR simulations showed that the SAR limits obey the guidelines as stipulated by the Federal Communication Commission (FCC) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for 1 mW of input power. The 2.45 GHz SAR limit for 1 g of human tissue is 0.09007 W/kg (FCC standard: < 1.6 W/kg) while for 10 g is 0.01867 W/kg (ICNIRP standard: < 2 W/kg). For 5.8 GHz, the SAR limit for 1 g of human tissue is 0.115 W/kg and for 10 g is 0.03517 W/kg. Based on the performance of the antenna in bending condition and the SAR limits, it is safe to conclude that the antenna can be used for wearable applications at 2.45 GHz and 5.8 GHz of the ISM bands.

Design of a 1×2 CPW Fractal Antenna Array on Plexiglas Substrate with Defected Ground Plane for Telecommunication Applications

In this paper, a fractal antenna array for telecommunication applications is presented. The proposed antenna array is realized on a Plexiglas substrate, has 1×2 radiating elements, and dimensions of 170mm×105mm. The antenna array is composed of two Koch Snowflake patches and is fed by a Coplanar Waveguide (CPW) transmission line. Radiating elements and the ground plane are printed on the top side of the substrate. Defected Ground Structure (DGS) technique is employed to enhance the bandwidth and improve the impedance matching. The proposed antenna array operates at two frequency bands, 1.08-1.32GHz covering the GPS band and 1.7-3.7GHz covering the GSM 1800/1900, UTMS, Bluetooth, LTE, and WiMAX bands. In addition, the antenna has a good performance with efficiency and peak gain of 82% and 6.3dB respectively. These characteristics allow the antenna to be an attractive candidate for telecommunication systems. Design and analysis of different structures were carried out with Ansys HFSS.

Parametric Analysis of the Defected Ground Structure-Based Hairpin Band Pass Filter for VSAT System on Chip Applications

In this study, a three-pole hairpin structure was fabricated on the top of the substrate material and an open loop microstrip structure at the ground to give a modified triple-band BPF with a unique design. A Rogers (RT5880) material with εr = 2.2 and thickness of 1.27mm was used to fabricate the proposed structure. The space between two consecutive hairpin resonators has different distances d1 and d2 with values of 0.2mm and 0.4mm respectively. The proposed filter offers a compact size with low return loss. The equivalent LC circuit of the DGS and hairpin structure is obtained with the Ansys electronic desktop and by using simple circuit analysis. The desired microstrip triple-band BPF operates at the Ku band, resonates at 10.28GHz, 12GHz, and 14.62GHz, while the simulated and experimental results are almost identical. The proposed wideband BPF satisfies the International Telecommunication Union ((ITU) region 3 spectrum requirements. Direct Broadcast Service (DBS) and Fixed Satellite Service (FSS) in transmit mode respectively employ the frequency band 11.41-12.92GHz and 14-14.5GHz.

Ultracompact Dual-Polarized Cross-Dipole Antenna for 5G Base Station Array of Low Wind Load

Very high wind loads represent one of the major problems for the ultralarge-scale 5G base station array at the sub-6 GHz band, where dozens of or hundreds of antennas are used. An ultracompact dual-polarized cross-dipole antenna with an extremely small overall projected area is presented. The array with low wind load is realized by miniaturized cross dipoles and the replacement of the traditional ground plane with a defected ground structure (DGS) and metal mesh reflector. The DGS is utilized to realize size reduction and isolation enhancement. The projected area of the antenna is reduced by 70%. Therefore, each antenna in the array can be independently packaged using a streamlined radome with a low wind load. And the inter-radome spacing is large enough to make holes that are used to further reduce wind load. The antenna prototype is designed, fabricated, and measured for the sub-1 GHz band. The measured results show that the impedance bandwidth is 680-970 MHz, the polarization isolation is higher than 20 dB, and the gain is around 6.5 dBi. It is verified that the proposed ultracompact antenna of high radiation performance is very suitable for an ultralarge-scale array of low wind load in a 5G base station.