This paper presents a novel platform for the efficient analysis, design, and optimization of ideal single-ended Class-E power amplifiers (PAs). It employs a comprehensive time-domain analytical model, which extends the conventional design space by incorporating variable duty cycles, variable voltage switching (VVS), and variable derivative voltage switching (VDS), enabling precise evaluation of key performance parameters such as harmonic efficiency, maximum output power capability, maximum operating frequency, and device stress. To facilitate practical design verification, an open-source, GUI-based CAD tool has been developed, providing researchers with an accessible and interactive environment for analysis and validation. In addition, a Python-based global optimization algorithm is integrated into the framework to automate component selection and enhance design robustness, particularly in scenarios involving finite DC-feed inductance. The accuracy and applicability of the proposed methodology are validated through nonlinear harmonic balance (HB) simulations. The results confirm the model’s ability to predict system behavior with high fidelity, making it a valuable resource for both academic and industrial design applications.

As smart radar sensors become increasingly integrated into modern life, this article provides a comprehensive tutorial for the design and implementation of a portable radar module, offering valuable design guidelines. The module operates in continuous wave (CW) modes, with selectable frequencies ranging from 2.25 to 2.50 GHz and a resolution of 100 kHz. A notable feature is its provision of both In-phase (I) and Quadrature (Q) components, which eliminates null points and enhances detection accuracy. The radar module integrates all necessary hardware components into a compact and efficient design, making it suitable for various security applications as well as non-contact monitoring and detection in the Internet-of-things (IoT) era.The design considerations outlined in this article highlight the module 2019;s versatility for various signal processing techniques, demonstrating its potential use in various applications for contactless sensing. Additionally, the discussion on utilizing in-house facilities to design and conduct simple experiments underscores the educational value of this module.

In their seminal work, Acar et al. (2007) proposed analytical design equations for Class E power amplifiers, which have significantly influenced subsequent research in this field. However, their analysis contains calculation errors in the evaluation of certain expressions, leading to inaccuracies in the derived design equations. This error results in significantly incorrect values for the design parameters, which, in turn, affect the accuracy of the overall design set. This work addresses these errors, providing a corrected set of design equations for Class E PAs, further supported by supplementary Python code, enabling researchers to readily explore and verify the corrected Class E design framework.

This paper presents a comprehensive analysis of Class-E series-tuned radio-frequency power amplifiers (RFPAs), focusing on their design and optimization for high efficiency and performance. However, achieving optimal performance involves navigating trade-offs among efficiency, bandwidth, harmonic suppression, output power capability, and device stress. This work examines the trade-offs involved in the series-tuned ((Formula presented.)) network and establishes the bounds for its quality factor using computer-aided harmonic balance (HB) simulations. Additionally, it explores optimal harmonic termination strategies to enhance the performance and efficiency of the design. Finally, a novel methodology using harmonic termination is proposed, simplifying the design process by eliminating the need for traditional load-pull extraction methods.

This paper presents a new architecture of a compact multimode FMCW radar for general purpose short-range applications. The radar can operate in CW as well as in FMCW modes. The transmitted RF frequency or frequency range can be arbitrarily selected using an inbuilt SPI control over 2.25-2.50 GHz with a frequency resolution of at least 100 kHz. A modified VCO-PLL loop with a stable reference source of 10 MHz improves the frequency stability. Other than the audio signal generator, all modules like RF blocks, base-band block DC power management block, and control and synchronization and data acquisition blocks are integrated into a single module using a three-layer PCB configuration. Fabrication and measurement of the radar unit in both the modes are presented.

An improved design of a cavity-backed slot ring antenna is presented. The antenna maintains its radiation characteristics and good impedance matching over at least 10 % frequency band. Over the band, the antenna does not show any beam tilt. Two higher order resonant modes are used to obtain high gain. The improved antenna characteristics is obtained by elevating a part of the top cavity plate containing the ring slot. A prototype antenna is designed and fabricated for 2.25-2.5 GHz short-range indoor radar applications. The antenna provides a measured gain of 7±0.5dBi over the entire band. The overall dimension of the antenna is 0.64λ0 × 0.64λ0 × 0.08 λ0, λ0 being the free space wavelength at the mid-band frequency. Design guidelines are provided for the frequency scaling.

Reports on initiatives by the IEEE to provide wireless communications and access to the Internet for educational purposes. As the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity, the IEEE has long been actively involved in outreach activities that bridge the digital divide. We, the members of the IEEE Antennas a n d Propagation Society (APS) and IEEE Microwave Theory and Technique s Society (MTT-S) Joint Student Branch Chapter (SBC) of the Indian Institute of Technology (IIT), Kharagpur (AP-MTT-SBC ITT Kharagpur), were also involved in a project to bridge the digital divide by exposing high school students to the basics of wireless communication and the Internet of Things (IoT). For four days (21-24 December 2020), the SBC ran outreach workshops for rural high school students. The main objective of the outreach workshop program was to acquaint as many students as possible who live in remote areas and lack financial and technical resources.

A non-coherent passive six-port receiver system is presented for accurate amplitude, phase and frequency measurement of a RF signal. The system uses the six-port network and a new wideband phase delay line with known phase profile. The phase delay unit uses a number of openstubs connected to a microstrip line. Detail design steps of the phase delay line is presented. The whole receiver is fabricated in PCB technology. No local oscillator or DC biasing are used. Thus, it is an all-passive system, which does not require any power source. It can be used as a real time and fast demodulator for both analog and digital signals.

This paper presents a broadside radiating wideband array antenna at 26.5 GHz. Both the TM ₁₁ and the next higher order mode, TM ₂₁ are excited on a single circular patch sitting on a large ground plane. The combination of these two modes provides elliptical beam in the broadside direction. Then, this patch is used as the basic radiating element for an array antenna. Because of the shaped radiation pattern, a 1 × 2 half wavelength array of the proposed antenna provides similar pattern like a 2 × 2 array of circular patches operating in only TM ₁₁ mode. With same inter element distance, a 1 × 2 array gives better performance in terms of gain bandwidth and size requirement as compared to conventional 2 × 2 array. Individual element size is slightly larger than the conventional TM ₁₁ mode antenna but the overall size of the array antenna is reduced to 50% without degrading the gain value. Further, the mode mixing technique provides a wide bandwidth and lower side lobe level. A prototype array element is fabricated in 1.52 mm thick RO4003C substrate. It provides an average broadside gain of 7.1 dBi with gain variation less than 0.8 dBi over 25.3527.65 GHz. The side lobe level is less than -14 dB from the broadside gain. Average total efficiency of the antenna is 86.6%.

This paper presents a compact continuous wave Doppler radar architecture at 2.4 GHz. The system provides a low-cost solution to remotely monitor vibrations of any object. In the RF system, two separate antennas are used for the transmitter and receiver. The receiver works in homodyne mode. A single microwave oscillator is used to transmit continuous wave signal as well as the synchronized local oscillator for the receiver. An opamp base band electronics separate the small receiver output signal from a large dc offset due to homodyne operation. In comparison to other approaches, number of components are minimized.