This letter introduces a novel electrically small antenna (ESA) with an inductive–capacitive resonator (LC-R) design tailored for compact handheld devices such as dongles, routers, tablets, and mobile handsets. The ESA integrates an LC resonator parasitically with the driven element to achieve a dual-band/wideband response in sub-6 GHz 5G new radio (NR) bands. Its key innovation is independence from device printed circuit board (PCB) size, maintaining matched impedance without external matching circuits. The fabricated prototype achieves impedance bandwidths (VSWR < 2) of 27.78% [(3.15 GHz to 4.15) GHz] and 20.77% [(4.4 GHz to 5.42) GHz] for 5G NR bands n77/n78/n79. Impedance performance is further validated on various PCB sizes, highlighting its versatility for wireless handheld applications.

This study introduces an innovative MIMO antenna tailored for 5G millimeter-wave applications. By integrating a rectangular closed loop (RCL) and split-ring resonators (SRRs) with a monopole structure, the design achieves notable enhancement in impedance performance around the 26.5 GHz frequency. The MIMO configuration comprises four radiating elements positioned on a common PCB with a space-efficient footprint of 30×30 mm2. The developed four-port antenna system offers a wide impedance bandwidth of 2 GHz (25.7−27.7GHz) centred at 26.5 GHz, achieving a total efficiency of 85−95% over the operating band. Additionally, the antenna exhibits envelope correlation coefficient (ECC) values within acceptable limits, ensuring excellent isolation between the ports. The antenna achieves an average gain of 7 dBi, confirming its effectiveness for deployment in millimeter-wave 5G New Radio (NR) bands n257, n258, and n261.

Seeing the rising applications of metamaterial in sensing and imaging, satellite communications, it becomes evident to design a high-gain microstrip patch antenna. To support these applications, this paper proposes a 7 x 7 array of planar novel metamaterial unit cells used as a superstrate to enhance the gain of microstrip patch antenna operating at 11.2 GHz. This proposed metamaterial structure yields a very low (near zero) value of effective refractive index at 11.2 GHz. Hence, the superstrate behaves as a near zero-indexed-medium (NZIM) around this frequency. NZIM superstrate are very popular because of their ability to focus the radiation and by utilizing this property, a significant gain enhancement has been achieved in the usage of patch antennas. Numerical simulations have been conducted using the CST Microwave studio, and obtained results corroborate that NZIM superstrate when suspended over a microstrip patch antennas significantly improves the gain around the value of 7.5 dB at 11.2 GHz, and efficiency is also improved

Seeing the recent rise in applications of RFID tags in industrial internet of things (IIoT), it become very evident to design an efficient and compact antenna which is able to satisfy the uprising IoT demands. This work presents a new 3D quasi-isotropic electrically small antenna (ESA) for RFID applications in the 2.4 GHz band. The proposed antenna is designed on a single perfect electric conductor (PEC) sheet by loading an inverted L-shaped slot. An opened aperture is excited to realize magnetic dipole characteristics to achieve a quasi-isotropic radiation pattern in 3D spatial coverage. The overall volume of the prototype is O.18Ax0.07Ax0.0096A nm3; here, ? is the free space wavelength that corresponds to operating frequencies. The proposed antenna offers a 30MHz (2.42-2.45 GHz) impedance bandwidth centered at 2.43 GHz. The antenna exhibits a quasi-isotropic radiation pattern with a maximum efficiency of 85%, which makes it suitable for RFID applications.

This work presents a novel frequency reconfigurable electrically small antenna (ESA) with a quasi-isotropic radiation pattern for ISM band applications within the 2.4 GHz band. The key contribution of this work is that a split ring resonator (SRR) is used parasitically with the electric dipole to realize a magnetic dipole-type radiation pattern. In addition, the proposed configuration is further configured with two p-i-n diodes to facilitate frequency reconfigurability to the antenna within the 2.4 GHz band. The SRR is arranged orthogonally with an electric curved dipole to achieve a uniform or quasi-isotropic radiation pattern in 3D spatial coverage. The overall size of the fabricated prototype is 0.13?×0.13? mm2; here, ? is the free space wavelength that corresponds to operating frequencies. The proposed antenna offers 40MHz bandwidth centered at 2.44GHz when the diodes (D1 & D2) are ON and a 30MHz bandwidth centered at 2.47GHz when the diodes (D1 & D2) are OFF. In both states, the antenna exhibits a quasi-isotropic radiation pattern with over 60% efficiency

This work presents an electrically small antenna (ESA) for wireless applications, such as digital cellular systems (DCS1800), WiMAX, and sub 6 GHz – 5G new radio (NR) systems. The proposed antenna offers a triple band resonance centered at 1.825, 3.3, and 3.58 GHz. Here, impedance matching networks of printed microstrip line sections, such as inverted ‘L’, open-ended line, meandered line, and capacitive stub, are used to achieve impedance matching at the desired frequencies. The total surface area of the proposed antenna is 0.14λ × 0.06λ, where λ is the wavelength at 1.825 GHz. The designed antenna is tested for its impedance and radiation characteristics. The fabricated prototype offers fractional bandwidth (FBW, with VSWR < 2) of 1.6%, 6%, and 6.7% centered at 1.825, 3.3, and 3.58 GHz, respectively, whereas for VSWR 3:1, the achieved fraction bandwidth(s) is 8.2% and 24.5% for the DCS1800 and 3.3 GHz band, respectively. The stable and nearly omnidirectional radiation pattern for each operating frequency bands indicates the suitability of the proposed antenna for the intended application(s).

This study presents an electrically small antenna loaded with a parasitic loop resonator for dual-band operations. The proposed configuration covers 2.4 GHz Bluetooth/Wi-Fi, 5G new radio (n79), and 5 GHz WLAN bands. In this study, a coplanar waveguide (CPW) feed L-shaped driven element is capacitively coupled with a parasitic loop resonator to get a dual-band response centered at 2.43 and 5.5 GHz, respectively. Further, an open-ended stub is attached with the driven element to achieve wide impedance bandwidth over the 5 GHz WLAN band. The overall dimension of the proposed antenna is 0.06λ × 0.2λ, where λ is the wavelength at 2.43 GHz. The parasitic loop resonator loaded electrically small antenna offers 60 and 1580 MHz impedance bandwidth (S11 < −10 dB). The stable impedance bandwidth and radiation characteristics of the proposed antenna validate its suitability for wireless application(s).