Asutosh Mohanty

A printed low-profile asymmetrical artificial magnetic conductor with circular polarization (CP) characteristics is presented in this article. The desired asymmetrical arrangement offers inherent advantages of manipulating the electromagnetic waves of high impedance surfaces with bandwidth and radiation improvement characteristics reminiscent of standard artificial magnetic conductor symmetric cells. Orthogonally rotational slot-based quarter mode stubs have been strategically used to develop a 4-port multiple-input multiple-output (MIMO) antenna that imitate bi-directional radiation modes (+ Z : Left-hand CP (LHCP) and - Z : Right-hand CP (RHCP)). Additionally, the MIMO layout has been retained ground connected topology with no additive isolation network, ensuring an effective isolation response in the operational band and good 10 dB impedance response. Experimental validation has shown with a fabricated prototype MIMO antenna is capable of operating from (2.64–4.28) GHz with a 10 dB impedance bandwidth of 47.4%, a 3 dB axial ratio (2.48–4.76) GHz with 63% 3 dB ARBW, a peak gain of 5.6 dBic, and inter-element port isolation > 20 dB. Good polarimetric purity or effective polarization contrasts are illustrated by the bi-directional LHCP and RHCP radiation patterns, indicating effective far-field diversity parameters with low envelope correlation coefficient < 0.01 and high diversity gain ≈ 9.994 values. The proposed 4-port MIMO antenna’s performance perspectives indicate its viability in lower Sub-6 GHz (n77/n78/n48) 5G NR frequency band applications.

A bi-pinnate leaflet-like slot design has been integrated on a Vivaldi antenna configuration (VAC) to imitate a 4-port multiple-input-mutiple-output (MIMO) nature-inspired antenna topology. Initially, a Referencess single port VAC is studied, and then the flared parts are etched in succession and periodically with a uniform pitch distance to resemble a pinnate leaflet. The customized design improves both the impedance and radiation characteristics. This inspires the conception of a shared radiator with a VAC multi-port topology, with each pertinent port driven by a simple umbrella-stick-type-feed (USTF). The USTF has been horizontally placed in proximity to the VAC circular slot, avoiding the need for traditional tapered feed and circular-cut transitions. Following the outlined design embodiments, a 4-port MIMO antenna was investigated, making it explicitly novel design in the shared radiator topology category with high isolation ( > 40 dB), high gain (10.3 dBi), and effective bandwidth (8.76–10.73) GHz. Four rectangular offsetted cut-outs have been recessed into the substrate to facilitate high isolation yet not impeding impedance or radiation response. Eventually, a prototype antenna measuring 2.5 λ 0 × 2.5 λ 0 × 0.05 λ 0 ( λ 0 = design test wavelength at 9.45 GHz) has been fabricated and demonstrate a good correlation with the simulated outcomes. High diversity gain DG > 9.9 dB and low correlational coefficients ECC < 0.002 are confirmed by the diversity parameters were evaluated in different environments, and potential outcomes reveal its feasibility for high frequency applications.

This study focused on a spatially decoupled 8‐port MIMO antenna, strategically designed for point‐to‐point (PTP) backhaul wireless applications at designated 7‐GHz frequency band. Utilizing a conventional dipole‐driven‐antenna‐element (DDAE), the design asserts a polygonal interface to assemble 8‐port MIMO configuration, avoiding additional isolation network. The initialization of DDAE study shows inductively dominant and capacitively coupled nature, which are primarily analyzed with modal synthesis on its resonance behavior and then extended to a sequential array configuration. This design topology self‐annihilate the trapped coupled signals from antenna ports without affecting its intrinsic resonance mechanism, and hence, good port‐isolation ( 24 dB) is achieved. The radiation mechanism shows discrete pattern diversification with stable high peak gain of 8.02 dBi at designated ports. To rationalize its counterparts, a prototype antenna has been fabricated and experimented to operate from 6.5 to 7.6 GHz for dedicated 7‐GHz PTP microwave backhaul RF wireless applications. The correlation coefficient between the antenna ports shows appreciable limits with ECC 0.2 viable for indoor, outdoor, and isotropic environments.