Feasibility Study on Measuring the Particulate Matter Level in the Atmosphere by Means of Yagi–Uda-Like Antennas

Abstract

In this work, the application of a technique for monitoring changes of the dielectric constant of the atmosphere caused by the presence of pollution is discussed. The method is based on changes in the reflection coefficient of the device induced by these dielectric constant variations of the surrounding medium. To that end, several Yagi–Uda-like antenna designs with different size limitations were simulated by using a Method-of-Moments software and optimized by means of a simulated annealing strategy. It has been found that the larger the optimal elements of the array are allowed to be, the higher the sensitivity reached. Thus, in a trade-off between sensitivity and moderate length (regarding flexibility purposes), the most promising solution has been built. This prototype has been experimentally tested in presence of an artificial aerosol made of PAO (polyalphaolefin) oil and black carbon inclusions of a size of 0.2 μm. As a result, potentials for developing a measurement procedure by means of changes in the characteristic parameters of the antenna led by different concentration levels of suspended particles in the surrounding medium are shown. In this manner, a local mapping of polluted levels could be developed in an easy, real-time, and flexible procedure.

Using Antenna Arrays with Only One Active Element for Beam Reconfiguration and Sensitive Study in Dielectric Media

“…An attempt with independent auxiliary arrays for each range yielded better results: an increase of in and of in . These results are similar to the obtained for antenna arrays with similar dipole length characteristics referred in [ 21 ].…”

“…The dielectric constant of a medium depends on the properties and abundance of its microscopic components. When electromagnetic radiation propagates in a medium with a dielectric constant (as sketched in Figure 3 ) its wavelength will be reduced as given by the following expression [ 21 ]: where is the wavelength corresponding to , and this will have an impact of the relative electric dimensions of the antenna. In such a way, the type and concentration of suspended matter in the air could be monitored; for instance, the modelling of particulate matter (PM) as spheres of dielectric constant with a volumetric concentration was used in [ 15 , 21 ] to compute an effective dielectric constant of the medium.…”

“…Afterwards, independent auxiliary arrays were added and optimized to achieve new radiation patterns or maximize the antenna response to changes in the dielectric constant of the medium. For the latter, two characteristic ranges of variation were chosen based on experimental effective dielectric constant measurements [ 21 ], from to and from to , optimizing one independent auxiliary array for each range. Furthermore, one further auxiliary array was optimized for an antenna working on both ranges effectively, switching from one to the other by displacing the auxiliary array (varying its aperture).…”

“…The dielectric constant of a medium depends on the properties and abundance of its microscopic components. When electromagnetic radiation propagates in a medium with a dielectric constant r (as sketched in Figure 3) its wavelength will be reduced as given by the following expression [21]:…”

“…An alternative, the use of antennas measuring composition through its effects on the dielectric constant of the medium, was successfully studied in [ 20 ] using a linear array of shunt slots in the broad wall of an air-filled rectangular waveguide. A more recent study further developed the method using Yagi-Uda-like antennas [ 21 ], of low-cost construction and operation requirements.…”