Description of the Coupling of two Loop Antennas using Electrical Equivalent Circuit Diagrams

EMC measurements must be carried out in standardized and defined measuring environments. The frequency range between 9 kHz and 30 MHz is a major challenge for measurement technology. The established test sites are designed with an perfect elelctrically conducting ground. For the considered lower frequency range, the metrological validation is carried out with magnetic field antennas in this frequency range. The aim is therefore to take into account the ferromagnetic properties of the ground plane in such a measurement environment and to describe them analytically or numerically with an electrical equivalent circuit diagram. In this article we simplify the model to two loopantennas in Freespace without groundplane to check if the approache with the ECD will work. Therefore we use various numerical field calculation programs in the frequency range up to 30 MHz. The results from simulations are to be checked for correctness with describing them analytically or numerically. For this purpose, a model consisting of two loop antennas was created and simulated in a numerical simulation program. In order to validate the results from the simulation, two different approaches to creating an electrical equivalent circuit (ECD) are examined. The first approach is based on the real equivalent circuit diagram of a coil and the second approach forms a parallel resonant circuit of the first resonance of an antennas input impedance. The focus here is on the mutual inductance, which represents the coupling between the two antennas.

Small Loop Antenna System Design for Radio Direction Finding

In this literature, a low-cost small loop antenna is developed for radio direction finding. It consists of two coupled rectangular counter-wiring loop antennas. A signal-processing circuit is developed also for demodulated outputs. A single rectangular loop antenna is discussed first for illustrating the receiving characteristics and then the proposed two coupled rectangular counter-wiring loop antennas are designed for radio direction finding. Measurements give a large linear detecting range. It is ready for Omni-directional application using another two coupled loop antennas and can be used as a tracking control device.

Plasma semiconductor antenna

The purposes of this work was to study the possibility of using photoconductive semiconductor antenna based on Ge or GaAs for receiving information signals in the frequency communications and satellite navigation bands and to study a scattering parameter S11 – a return loss (a reflection coefficient) of configurable loop antennas with laser-plasma control based on semiconductor photoresistor. It is shown that the addition of semiconductor photoresistor element in the loop antenna makes it possible to significantly expand its functionality and control its characteristics using an external laser source.

A Flexible Single Loop Setup for Water-Borne Transient Electromagnetic Sounding Applications

Water-borne transient electromagnetic (TEM) soundings provide the means necessary to investigate the geometry and electrical properties of rocks and sediments below continental water bodies, such as rivers and lakes. Most water-borne TEM systems deploy separated magnetic transmitter and receiver loop antennas—typically in a central or offset configuration. These systems mostly require separated floating devices with rigid structures for both loop antennas. Here, we present a flexible single-loop TEM system, the light-weight design of which simplifies field procedures. Our system also facilitates the use of different geometries of the loop antenna permitting to adjust the depth of investigation (DOI) and the minimum sounding depth in the field. We measure the turn-off ramp with an oscilloscope and use the DOI to assess the minimum and maximum exploration depth of our single-loop TEM system, respectively. A reduction of the loop-antenna size improves early-time TEM data due to a reduced length of the turn-off ramp, whereas an increase of the loop-antenna size enhances the signal strength at late times, which allows to investigate deeper structures below the lake bed. We illustrate the capabilities of our system with a case study carried out at Lake Langau in Austria. Our results show that our system is capable of reaching a DOI of up to 50m (with a maximum radius of the circular loop of 11.9m), while it also resolves the water layer down to a minimum thickness of 6.8m (when the radius is reduced to 6.2m).

Calibration of Ultrasonic Flaw Detectors in accordance with ISO 22232-1:2020

This paper presents the procedure developed at SCL for the calibration of loop antennas for test frequencies from 9 kHz to 30 MHz in accordance with CISPR 16-1-6:2014+AMD1:2017. The background, measurement model and uncertainty components are introduced and discussed. The expanded measurement uncertainty is estimated as 1.2 dB.

Calibration of Loop Antennas in Accordance with CISPR 16-1-6:2014+AMD1:2017

This paper presents the procedure developed at SCL for the calibration of loop antennas for test frequencies from 9 kHz to 30 MHz in accordance with CISPR 16-1-6:2014+AMD1:2017. The background, measurement model and uncertainty components are introduced and discussed. The expanded measurement uncertainty is estimated as 1.2 dB.

LOOP ANTENNA WITH A SEMICONDUCTOR ELEMENT

Представлены результаты исследований рамочной антенны, в которой подстроечным элементом является фоторезистор, управляемый лазерным излучением. Показано, что использование фоторезистора как элемента внешнего контура рамочной антенны, включенного последовательно, позволяет изменять согласование рамочной антенны с помощью внешнего лазерного источника. Представлены результаты исследований характеристик коэффициента передачи рамочных антенн, состоящих из медной фольги на диэлектрической основе и полупроводникового элемента. Установлено, что при изменении интенсивности лазерного излучения, падающего на полупроводниковый элемент-фоторезистор, изменяется коэффициент отражения рамочной антенны. В диапазоне от 10 МГц до 18ГГц получены зависимости коэффициентов отражения (Su)рамочных антенн с полупроводниковым элементом. Проведено сравнение рамочной антенны и рамочной антенны с фоторезистором. The results of an experiment with a loop antenna, in which the building element is a photoresistor controlled by laser radiation, are presented. It is shown that the use of a photoresistor as an element of the external contour of a loop antenna connected in series makes it possible to change the matching of the loop antenna due to an external laser source. The results of studies of the characteristics of the transmission coefficient of loop antennas consisting of a dielectric copper foil and a semiconductor element are presented. It was found that when the intensity of the laser radiation incident on the semiconductor element-photoresistor changes, the reflection coefficient of the frame antenna changes. In the range of 10 MHz-18 GHz, the dependences of the reflection coefficients (S11) of loop antennas with a semiconductor element are obtained. A comparison is made between a loop antenna and a loop antenna with a photoresistor.

Design and Performance Analysis of Compact Wearable Textile Antennas for IoT and Body-Centric Communication Applications

This paper presents two compact textile-based planar dipole and loop antennas for wearable communication applications operating in the 2.4 GHz industrial, scientific, and medical radio (ISM) bands. The antennas were fabricated on a 0.44 mm thin camouflaged-military print, cotton jean cloth using conductive copper threads, and sewing embroidery technique to create the radiating structure. Design and performance analyses of the antennas were carried out using simulations; further experiments were performed in anechoic chamber and indoor environment to validate the designs. The experiments were carried out in a free space scenario and on the various locations of the human subject such as the torso and limb joints. The performance of the antennas was investigated based on the reflection coefficient in normal and bent conditions corresponding to the different radii of the locations of the human limbs. The antennas perform well in free space and on-body scenarios in flat and bend conditions providing return loss below −10 dB in all cases with an acceptable resonant frequency close to 2.4 GHz due to the antenna bending and body effects. The radiation pattern measurements are also reported in this work for free space and on-body scenarios. It is observed that the presence of the human body significantly influences the antenna radiation pattern which leads to an increase in the front-to-back ratio and also makes the antenna more directive. Overall, the performance of the fabricated embroidered textile antennas was found suitable for various wearable body-centric applications in indoor environments.