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This brief presents a novel frequency-reconfigurable self-diplexing antenna (SDA) utilizing a hybrid substrate-integrated waveguide (SIW). The antenna comprises a radiating slot, a feeding network, and a hybrid SIW cavity featuring half-mode circular and half-mode rectangular SIW structures. The unique feature of this antenna lies in its fine-tuning capability of each resonant frequency by inserting or injecting solid and liquid dielectrics into designated etched pockets. Experimental results demonstrate that the proposed structure can be effectively tuned within the frequency range of 2.7 to 3.47 GHz for the lower band and 4.05 to 4.96 GHz for the upper band. The mutual coupling between the ports is better than 20.4 dB, and the antenna maintains consistent radiation patterns across the entire operating range. The proposed tunable antenna, featuring precise frequency tuning capability, compact size, and stable radiation patterns, is well suited for various applications, including wireless communication systems, biomedical telemetry, microwave imaging, WiMAX, and Wi-Fi.

This brief describes the novel fully 3D-printed dual-band RF energy harvester suitable for wireless sensor network green IoT applications. The proposed energy harvesting system is composed of a dual-band circular omnidirectional monopole antenna array with a T-junction power divider, RF rectifier, and an impedance matching network. The circular monopole antenna array is conformed to a cylindrical substrate to achieve the compact system. The Villard multiplier-based rectifier has been used for the conversion of RF signal to DC voltage. The presented rectenna is fabricated using a 3D printable, biodegradable, conformal and an economical substrate. The test is performed in an RF ambient environment. The manufactured configuration obtained conversion efficiencies of 67.29% with output voltage of 1.39 V and 42.16% with output voltage of 1.1 V at 0 dBm RF input power in 2.4 GHz and 5.2 GHz frequency bands respectively. The proposed configuration’s simulated and measured results are in concordance with each other. The study emphasizes the potential of 3D-printed rectenna in terms of cost-effective prototyping.

This brief presents a novel design of a miniaturized self-triplexing antenna (STA) based on the shielded half-mode substrate integrated waveguide (S-HMSIW) for WiFi/WLAN/ISM-band applications. The S-HMSIW is constructed by assembling one row of vias and an open slot at the open-ended side of the conventional HMSIW. This configuration increases the quality factor and minimizes unwanted radiation loss, which allows for achieving high performance. A modified inverted U-shaped slot is created on the top plane of the cavity to form three different radiating patches, which are excited by three independent $50~\Omega $ microstrip feedlines to operate at three different frequencies. The proposed STA exhibits competitive features such as highly compact size ( $0.09\lambda _{g}^{2}$ ), high isolation (>33dB), and gain ( $>4.8$ dBi), which makes it suitable for handheld communication devices. The simulated and measured circuit responses are in good agreement.

This work introduces a novel frequency tunable self-diplexing antenna (SDA) design based on substrate integrated waveguide (SIW) technology. A modified A-shaped slot is employed on the cavity’s top plane, which is excited by two independent $50~\Omega $ microstrip feed lines to operate at each resonant frequency. The frequency flexibility of the proposed antenna allows for fine-tuning at each resonance frequency. The frequency flexibility has been achieved by employing the substrate’s air- and liquid-filled pockets. The proposed antenna can be configured to operate in the 3.5-3.8 GHz and 5.53-6.2 GHz bands, as demonstrated by the simulation results. With distilled water-filled pockets, the proposed antenna offers peak gains of 5.04 dBi and 5.26 dBi. The proposed SDA exhibits competitive features such as a highly compact size of $0.22\lambda _{g} ^{2}$ and high isolation (>27dB), which makes it suitable for handheld communication devices. The simulated and measured circuit responses are in good agreement.