12Overall dissipation of pesticides from plants is frequently measured, but the contribution of 13 individual loss processes is largely unknown. We use a pesticide fate model for the quantification of 14 dissipation by processes other than degradation. The model was parameterized using field studies.

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Recently, water has been proposed as an interesting candidate for use in applications such as tunable microwave metamaterials and dielectric resonator antennas due to its high and temperature-dependent permittivity. In the present work, we considered an electrically small water-based dielectric resonator antenna made of a short monopole encapsulated by a hemispherical water cavity. The fundamental dipole resonances supported by the water cavity were used to match the short monopole to its feed line as well as the surrounding free space. Specifically, a magnetic (electric) dipole resonance was exploited for antenna designs with a total efficiency of 29.5% (15.6%) and a reflection coefficient of −24.1 dB (−10.9 dB) at 300 MHz. The dipole resonances were effectively excited with different monopole lengths and positions as well as different cavity sizes or different frequencies in the same cavity. The overall size of the optimum design was 18 times smaller than the free-space wavelength, representing the smallest water-based antenna to date. A prototype antenna was characterized, with an excellent agreement achieved between the numerical and experimental results. The proposed water-based antennas may serve as cheap and easy-to-fabricate tunable alternatives for use in very high frequency (VHF) and the low end of ultrahigh frequency (UHF) bands for a great variety of applications.

With its high-permittivity in the microwave frequency range, water has the potential as an alternative, inexpensive, bio-friendly and abundant material for many microwave applications such as dielectric resonator antennas and tunable metamaterials. Huygens antennas, composed of singleelement structures supporting a special combination of electric and magnetic modes, provide an alternative route for compact and directive antennas. In this work, we investigate a subwavelength water-based Huygens dielectric resonator antenna with strongly excited electric and magnetic dipoles at around 350 MHz. Our antenna leads to the directivity of 6 and a radiation front-to-back ratio of 40.3 dB. Additionally, good matching to the feed-line and the surrounding free space were achieved with a reflection coefficient of-38.3 dB and a total efficiency of 57.8 %. The antenna was fabricated and characterized with excellent agreement between the measurements and the numerical results. Furthermore, several means of tuning the antenna were tested numerically and experimentally. We believe that the proposed water-based Huygens dielectric resonator antenna may serve as an easy-to-fabricate and cheap alternative for the VHF and low end of the UHF bands.

Tunable devices are of great interest as they offer reconfigurability to their operation, although many of them employ rare and expensive materials. In a world with increasing focus on ecological compatibility and recyclability, immense efforts are being made to find bio-friendly alternatives. However, in some cases, one does not have to look far, because water, a high-permittivity dielectric at microwave frequencies, is readily available. Recent studies have shown that compact Mie resonators, which are the fundamental blocks in all-dielectric metamaterials and dielectric resonator antennas, can be realized with small water elements. In a variety of applied physics areas, encompassing frequencies from the radio to the optical parts of the spectrum, all-dielectric implementations have received immense attention. When it comes to water, its temperature-dependent permittivity and liquidity enable a multitude of unprecedentedly simple means to reconfigure and tune the resulting devices. Moreover, being a polar solvent, water easily dissolves various physiologically important electrolytes, which potentially can be exploited in a sensor design. Presently, we review water-based devices for advanced microwave control and sensing. We show and discuss the dynamic properties of water and examine the microwave scattering and absorption characteristics of single water elements. We investigate how such water elements can be employed in various microwave designs, including single resonators, metamaterials, metasurfaces, antennas, absorbers, and radio frequency components. The main complications of water are its losses, especially at higher microwave frequencies, and its stability. We discuss how to overcome these and show that even highly loss-sensitive modes, namely, toroidal modes and bound states in the continuum, can be realized with water-based devices. We believe that water-based devices usher the route to meet the UN proclaimed goals on global sustainability and human-friendly environment.