This paper focuses on a printed inverted-F antenna (PIFA) with meandering line and meandering shorting strip under 2.4 GHz industrial, scientific, and medical (ISM) band for Internet of things (IoT) applications. Bluetooth Low Energy (BLE) technology is one of potential platforms and technologies for IoT applications under ISM band. Printed circuit board (PCB) antenna commonly used in commercial and medical applications because of its small size, low profile, and low cost compared to low temperature cofired ceramic (LTCC) technology. The proposed structure of PIFA is implemented on PCB to gain all these advantages. Replacing conventional PCB line in PIFA by the meandering line and meandering shorting strip improves the efficiency of the PIFA as well as the bandwidth. As a case study, design and measurement results of the proposed PIFA are presented.

This article presents a simple wideband rectangular antenna in foldable and non-foldable (printed circuit board (PCB)) structures for Internet of Things (IoT) applications. Both are simple structures with two similar rectangular metal planes which cover multiple frequency bands such as GPS, WCDMA/LTE, and 2.4 GHz industrial, scientific, and medical (ISM) bands. This wideband antenna is suitable to integrate into the short- and long-range wireless applications such as the short-range 2.4 GHz ISM band and standard cellular bands. This lowers the overall size of the product as well as the cost in the applications. In this article, the configuration and operation principle are presented as well as its trade-offs on the design parameters. Simulated and experimental results of foldable and non-foldable (PCB) structures show that the antenna is suited for IoT applications.

Expressions in the form of operators that enable one to calculate the intensity of allowed ( A M = 1, A m = 0) and 'forbidden' ( A M = 1, A m = t l ) hyperfine EPR lines have been derived ( M and m denote, respectively, the electron and nuclear magnetic quantum numbers). The spin Hamiltonian considered consists of the electron Zeeman, zero-field and hyperfine terms. The axis of quantization for the nuclear spin is assumed to be along the direction of the effective magnetic field at the nucleus. The variousspin Hamiltonian 'tensors' are considered to be anisotropic, having non-coincident principal axes. These operators depend only on the components of the spin operators S and I along their respective axes of quantization. To calculate the intensity, it is sufficient to determine the square of the matrix elements of these operators between the zero-order states that take part in resonance. The present results are compared with those published previously. The angular variation in the intensity calculated using the present expressions compares favourably with experimental values.

Expmions are derived tor determining the angular variation in the intensity of the forbidden hyperfine transitions ( A M = 1, Am = i2) in the EPR spectra of Wansition ions. The intensities calculated using these expressions are mmpared with the predictions of Bleaney and Rubins and of Bir. It is found that third-order contributions arising from the nuclear spin operator as well as the quadmpole term are important in interpreting the intensity of forbidden hyperfine lines.