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This paper introduces a novel design methodology for a dual-band branch-line coupler (DBBLC) that, for the first time, facilitates practically unlimited band ratio, enhanced flexibility in power division, and arbitrary port termination impedance concurrently. This approach ensures precise power distribution, matching, and isolation requirements by utilizing a generalized coupler core paired with an L-section impedance-matching network. This paper details an innovative and comprehensive analytical strategy for DBBLC design, which overcomes the limitations noted in prior research by deriving a generalized formula for the power division ratio (k) and simplifying the design equations to decrease complexity. This method enables the simultaneous realization of varied power division ratios, frequency ratios (r), and port impedances ( Zp ), thus offering remarkable design versatility. The effectiveness of this new analytical design methodology is corroborated through several design examples. Moreover, two prototype models operating at 1 GHz/2.5 GHz ( r=2.5,k=0 dB) and 1 GHz/2 GHz ( r=2,k=4.77 dB) frequencies, constructed on Rogers’ RO4003C substrate, exhibit >22 dB return loss, <0.64 dB amplitude imbalance as well as <1° phase imbalance of the transmission parameters and >25 dB isolation at all the targeted frequencies. Therefore, the development and validation of this new DBBLC structure, as demonstrated by the strong correlation between our simulated and experimental findings, not only surpasses the capabilities of existing models, but also broadens the applicability of dual-band couplers in modern wireless communication systems. 

There is a great military, space, and industry need for wireless systems that can operate under extreme conditions such as high temperatures and harsh chemical environments. Some of the applications inc lude planetary rovers for space exploration missions, wireless systems for mining and oil drilling applications, monitoring combustion turbines, and wireless environmental monitoring of first responders. Since antennas are the most critical components of a wireless system, design of antennas capable of surviving harsh environments is significant for overall system reliability and efficient communication. Yttria-Stabilized Zirconia (YSZ) is a ceramic, which has been recently used in a wide variety of gas sensing, biomedical, and thermal applications. YSZ has properties of high temperature tolerance, moisture resistance, high strength and corrosion resistance, and structural stability. One of the recent applications of YSZ is its utilization as a substrate material in the design of patch antennas. The electrical properties of YSZ allows for designing antennas with compact form factor and high efficiency due to high relative permittivity and low loss tangent. 

Zirconia Ribbon Ceramic (ZRC) is a commercially available ceramic that can be a potential low-loss substrate for radio frequency (RF) devices suitable for high temperatures and harsh environmental conditions. In this paper, the RF characteristics of ZRC are determined in the frequency band of 0.5 GHz to 5 GHz. A T-resonator is designed and fabricated for the transmission coefficient measurements to obtain complex permittivity (dielectric constant and loss tangent) values of the material. The dielectric constant is shown to be steady at 32.2, while the loss tangent is found to be at 0.001 in the band of interest. 

This research proposes an inkjet printed dual-band dual-sense circularly polarized antenna using CPW-feeding on PET substrate. The antenna is designed and optimized using ANSYS HFSS, which operates at 4.01 GHz - 5.05 GHz (22.96%) and 6.23 GHz - 7.58 GHz (19.55%) with a return loss of <−10 dB. On top of that, the antenna shows an axial ratio of less than 3 dB at 4.23 GHz - 4.62 GHz (8.81%) and 7.11 GHz - 7.36 GHz (3.45%), whereas left hand circular polarization (LHCP) is observed in the first band and right hand circular polarization (RHCP) is observed in the second band. The overall dimensions of the antenna is x x , where is the free-space wavelength at the lowest circular polarization frequency. Measurement of the fabricated version shows good agreement with the simulated version. To the best of author’s knowledge, this proposed design is the first circularly polarized … 

In recent years, inkjet printing has become a popular form for creating sensors and antennas. These devices are fabricated using different materials with inkjet printing using various (conductive, oxide, biological) inks on predominantly flexible substrate. This form of fabrication has attracted much attention for a variety of reasons such as relatively cheap cost of manufacturing and materials, as well as the ease of use and high customization. These devices also provide a lighter frame and added flexibility allowing them to be incorporated as devices on non-planar surfaces. It is also possible for inkjet printing to be used as a sustainable manufacturing method, providing a method of reducing electronic waste. In this article, several topics related to inkjet printing are covered. These topics include a general overview of the fabrication process of inkjet devices through an inkjet printer, recent applications of inkjet-printed sensors, applications of inkjet-printed antennae, challenges in inkjet printing, and an outlook on the inkjet printing. In the fabrication section, the different materials and printing process are explored. Topics covered in the application section include gas sensors, biomedical sensors, pressure sensors, temperature sensors, glucose sensors, and more. In the inkjet antennas portion of the article, RFID tagging and 5G applications are highlighted. The main challenges covered are specific to fabrication that are being currently addressed.

 

In this paper, a Multi-Input Multi-Output (MIMO) antenna of 4 monopole elements is presented on Zirconia Ribbon Ceramic (ZRC) substrate. Utilization of this substrate material allows an implementation of an antenna system that is able to withstand harsh environments and high temperatures due to inherent substrate characteristics. The proposed MIMO design supports an operational antenna bandwidth from 2.44 GHz to 2.55 GHz with a center frequency around 2.5 GHz covered by all 4 antenna elements. High antenna isolation below -15 dB is obtained among the ports. The antenna also provides a peak gain over 3 dB through the entire band of interest (3.34 dB at 2.5 GHz) and low cross-polarization. 

In this paper, a simple, and compact CPW-fed circularly polarized antenna is presented. The proposed antenna consists of a modified “S” shaped patch which has slots in three different places along with a slot in the ground plane. These slots contribute in increasing the bandwidth of the axial ratio. The antenna has a 3 dB axial ratio bandwidth of 10.47% (4.07 GHz–4.52 GHz) and an impedance bandwidth of 17.53% (3.8 GHz – 4.53 GHz) covering the full region of axial ratio band. Moreover, this antenna is designed using PET paper which makes it flexible in nature and the first flexible antenna in discussed frequency range to the best of author’s knowledge. 

Development in the field of gas sensors has witnessed exponential growth with multitude of applications. The diverse applications have led to unexpected challenges. Recent advances in data science have addressed the challenges such as selectivity, drift, aging, limit of detection, and response time. The incorporation of modern data analysis including machine learning techniques have enabled a self-sustaining gas sensing infrastructure without human intervention. This article provides a birds-eye view on data enabled technologies in the realm of gas sensors. While elaborating the prior developments in gas sensing related data analysis, this article is poised to be an entrant for enthusiast in the domain of data science and gas sensors.