Radiation Profile of 2.45 GHz Bi-Circular Loop Antenna using Parabolic Reflector Made of Frying Pan (Wajanbolic)

This study aims to determine the dimensions of the antenna and reflector which can optimally work at a frequency of 2.45 GHz. A good antenna is an antenna that has high directive capability, high performance, and inexpensive. In this work, the proposed antenna model was a Bi-Circular Loop (BCL) with a reflector using a frying pan (Wajanbolic). The methods were used in this research for instance computational simulation, fabrication, and characterization. Simulations were carried out using the Finite Different Time Domain (FDTD) technique. The simulation results were compared with the measurement process. In the first simulation, four reflectors sizes could qualify as antennas, namely diameters of 309.00 mm, 335.00 mm, 364.00 mm, and 381.00 mm. The four reflectors sizes were optimized by changing the radius parameter of the BCL antenna. The best results were obtained on the reflector with a diameter of 364.00 mm and a BCL radius of 17.38 mm. The simulation results showed a radiation profile consisting of an RL value of -35.69 dB and a gain value of 16.40 dBi. Based on the fabrication and measurement of the antenna, the RL value was -54.75 dB and the directional antenna gain was 16.00 dBi. An antenna with such performance can be used as a point-to-point Wi-Fi transmitter.

Making it Concrete: Analysing the Role of Concrete Plants’ Locations for Circular City Policy Goals

Increasingly, space for remanufacturing is seen as the most valuable resource to achieve circular economy (CE) policy goals, in particular for cities. However, in many cities, industrial urban areas are increasingly subject of – mostly circular designed - residential redevelopment. The proposition of this paper is that these diminishing industrial areas host, at least potentially, essential functions necessary to “close the material loop.” The reason why policy makers neglect the necessity of remanufacturing capacity, is because it is difficult to pinpoint the “ideal” geography of a circular loop. Most (circular) products can be transported limitless, thus their remanufacturing functions can be located around the world. But what if a critical material cannot be transported limitless and has circular potential? Therefore, this paper focusses on concrete for two reasons. First, concrete is by far the most abundant material in urban areas. Second, newly/circular made fluid concrete can only be transported for a limited time and distance. The hypothesis of this paper is that concrete plants are and will become essential for circular cities. Subsequently, we focus on the Dutch city of The Hague and combine a Material Flow Analysis with the locations of the concrete resupply chain. Our results show that potentially The Hague has a 100% circular concrete chain, but the importance of its concrete plant is (implicitly) neglected. We conclude that The Hague is illustrative for the problem of many circular cities that are without (implicitly) taking into account the whole circular resupply chain, jeopardized today a future urban CE.

Innovative Design and Analysis of an Electrically Small Reconfigurable Antenna for GPS and Blue Tooth Applications

In this paper, an electrically small, planar antenna with broad side radiation pattern is presented. The design contains a dipole and a segmented circular loop which works equivalent to that of a magnetic dipole. A circular patch with slots is used to provide impedance matching. In general, electrically small antennas suffer from narrow bandwidth. In this paper, the reconfigurability of the small antenna for two different applications, 1.5GHz and 2.4GHz, is discussed. This reconfigurability was achieved by using a BAR 64-03W pin diode to adjust the resonant frequency. Two reconfigurable frequency bands were achieved at 1.5GHz and 2.4GHz with broad side radiation patterns.

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).

Modeling Antenna Radiation Using Artificial Intelligence Techniques

The forward and the inverse problem of a thin, circular, loop antenna that radiates in free space is modeled and solved by using soft computing techniques such as artificial neural networks and adaptive neuro fuzzy inference systems. On the one hand, the loop radius and the observation angle serve as inputs to the forward model, whereas the radiation intensity is the output. On the other hand, the electric field intensity and the loop radius are the input and output, respectively, to the inverse model. Extensive numerical tests indicate that the results predicted by the proposed models are in excellent agreement with theoretical data obtained from the existing analytical solutions of the forward problem. Thus, the employment of artificial intelligence techniques for tackling electromagnetic problems turns out to be promising, especially regarding the inverse problems that lack solution with other methods.