High Gain Beam Steering Antenna Arrays with Low Scan Loss for mmWave Applications

In millimeter-wave (mmWave) communications, the antenna gain is a crucial parameter to overcome path loss and atmospheric attenuation. This work presents the design of two cylindrical conformal antenna arrays, made of modified rectangular microstrip patch antenna as a radiating element, working at 28 GHz for mmWave applications providing high gain and beam steering capability. The microstrip patch antenna element uses Rogers RO4232 substrate with a thickness of 0.5 mm and surface area of 5.8 mm × 5.8 mm. The individual antenna element provides a gain of 6.9 dBi with return loss bandwidth of 5.12 GHz. The first antenna array, made by using five conformal antenna elements, achieves a uniform gain of approximately 12 dBi with minimal scan loss for extensive scan angles. In the second antenna array, a dielectric superstrate using Rogers TMM (10i) was used to modify the first antenna array. It enhanced the gain to approximately 16 dBi while still maintaining low scan loss for wide angles. The proposed array design method is very robust and can be applied to any conformal surface. The mathematical equations are also provided to derive the array design, and both array designs are verified by using full-wave simulations.

A multifunctional ultrathin flexible bianisotropic metasurface with miniaturized cell size

In this paper, a flexible bianisotropic metasurface possessing omega-type coupling is presented. The designed metasurface behaves differently when excited from either forward (port 1) or back (port 2) sides. It provides an absorption of 99.46% at 15.1 Gigahertz (GHz), when illuminated from port 1, whereas, on simultaneous illumination from port 2, it behaves like a partially reflective surface (PRS). Furthermore, the presented metasurface not only acts as an in-band absorptive surface (port 1) and partially reflective surface (port 2), but it also provides 97% out-of-band transmission at 7.8 GHz. The response of the presented metasurface remains the same for both transverse Electric (TE) and transverse magnetic (TM) polarized wave or any arbitrary linearly polarized wave. Additionally, the response of the metasurface is angularly stable for any oblique incidence up to 45º. The proposed ultrathin flexible metasurface with absorption, partial reflection and out-of-band transmission properties can be used in the Fabry Perrot cavity antenna for gain enhancement with radar cross-section (RCS) reduction both for passband and stop-band filtering, and conformal antenna applications.

A Dual-Band Conformal Antenna Based on Highly Conductive Graphene-Assembled Films for 5G WLAN Applications

Flexible electronic devices are widely used in the Internet of Things, smart home and wearable devices, especially in carriers with irregular curved surfaces. Light weight, flexible and corrosion-resistant carbon-based materials have been extensively investigated in RF electronics. However, the insufficient electrical conductivity limits their further application. In this work, a flexible and low-profile dual-band Vivaldi antenna based on highly conductive graphene-assembled films (GAF) is proposed for 5G Wi-Fi applications. The proposed GAF antenna with the profile of 0.548 mm comprises a split ring resonator and open circuit half wavelength resonator to implement the dual band-notched characteristic. The operating frequency of the flexible GAF antenna covers the Wi-Fi 6e band, 2.4–2.45 GHz and 5.15–7.1 GHz. Different conformal applications are simulated by attaching the antenna to the surface of cylinders with different radii. The measured results show that the working frequency bands and the radiation patterns of the GAF antenna are relatively stable, with a bending angle of 180°. For demonstration of practical application, the GAF antennas are conformed to a commercial router. The spectral power of the GAF antenna router is greater than the copper antenna router, which means a higher signal-to-noise ratio and a longer transmission range can be achieved. All results indicate that the proposed GAF antenna has broad application prospects in next generation Wi-Fi.