Electromagnetic radiation interference

Radome Also called radiation dome. It is a cover for a microwave antenna used to protect the antenna from the environment on the ground, underwater, and in the air (aircraft nose cone, etc.). The dome is basically transparent to electromagnetic radiation and structurally strong. Different materials have been used such as wood, rubber-coated air-supported fabric, etc. The most popular is the use of glass fiber-TS polyester RPs. The shape of the dome, that is usually spherical, is designed not to interfere with the radiation. 

FIGURE 1.19 In this illustration, the peaks of the waves of electromagnetic radiation are represented by orange lines. When radiation coming from the left (the vertical lines) passes through a pair of closely spaced slits, circ ular waves are generated at each slit. These waves interfere with each other. Where they interfere constructively (as indicated by the positions of the dotted lines), a bright line is seen on the screen behind the slits where the interference is destructive, the screen is dark. 

When two or more waves pass through the same region of space, the phenomenon of interference is observed as an increase or a decrease in the total amplitude of the wave (recall Fig. 1.20). Constructive interference, an increase in the total amplitude of the wave, occurs when the peaks of one wave coincide with the peaks of another wave. If the waves are electromagnetic radiation, the increased amplitude corresponds to an increased intensity of the radiation. Destructive interference, a decrease in the total amplitude of the waves, occurs when the peaks of one wave coincide with the troughs of the other wave it results in a reduction in intensity. 

So far we have only considered scalar interference, however, the vector nature of electromagnetic radiation can give rise to polarization interference... 

Mossbauer resonance of Zn to study the influence of the gravitational field on electromagnetic radiation. A Ga ZnO source (4.2 K) was used at a distance of 1 m from an enriched ZnO absorber (4.2 K). A red shift of the photons by about 5% of the width of the resonance line was observed. The corresponding shift with Fe as Mossbauer isotope would be only 0.01%. The result is in accordance with Einstein s equivalence principle. Further gravitational red shift experiments using the 93.3 keV Mossbauer resonance of Zn were performed later employing a superconducting quantum interference device-based displacement sensor to detect the tiny Doppler motion of the source [66, 67]. 

X-rays Electromagnetic radiation with wavelengths ranging between 10"10 and lO cm. X-rays diffraction A physical method for determining the structure of crystalline solids by exposing the solids to X-rays and then studying the varying intensity of the difracted rays due to interference effects. 

Electromagnetic radiation has its origins in atomic and molecular processes. Experiments demonstrating reflection, refraction, diffraction and interference phenomena show that the radiation has wave-like characteristics, while its emission and absorption are better explained in terms of a particulate or quantum nature. Although its properties and behaviour can be expressed mathematically, the exact nature of the radiation remains unknown. 

As with prisms, there are other devices that have been historically used for dispersing or filtering electromagnetic radiation. These include interference filters and absorption filters. Both of these are used for monochromatic instruments or experiments and find little use compared to more versatile instruments. The interested reader is referred to earlier versions of instrumental analysis texts. 

Optical fiber detectors (OFD) are devices that measure electromagnetic radiation transmitted through optical fibers to produce a quantitative signal in response to the chemical or biochemical recognition of a specific analyte. Ideally, an OFD should produce a specific and accurate measurement, continuously and reversibly, of the presence of a particular molecular species in a given sample medium. Additionally, OFD should pro vide maximum sensitivity and minimal interferences fromsuperfluous ions or molecules to obtain low detection limits. Other attractive features include the miniaturization of the fiber s tip to accommodate single-cell analysis and portable instrumentation to allow in situ analysis. 

Cage effect. Electromagnetic radiation will be caged in small compartments of m-size according to interference. Quantumelectrodynamic calculations propose an increase of the radiation density up to a factor of 106, and correspondingly the release of radiation will be damped. 

The basic layout of a simple dispersive IR spectrometer is the same as for an UV spectrometer (Figure 2.1), except that all components must now match the different energy range of electromagnetic radiation. The more sophisticated Fourier Transform Infrared (FTIR) instruments record an infrared interference pattern generated by a moving mirror and this is transformed by a computer into an infrared spectrum. 

Microwaves are electromagnetic radiation placed between infrared radiation and radio frequencies, with wavelengths of 1 mm to 1 m, which corresponds to the frequencies of 300 GHz to 300 MHz, respectively. The extensive application of microwaves in the field of telecommunications means that only specially assigned frequencies are allowed to be allocated for industrial, scientific or medical applications (e.g., most of wavelength of the range between 1 and 25 cm is used for mobile phones, radar and radio-line transmissions). Currently, in order not to cause interference with telecommunication devices, household and industrial microwave ovens (applicators) are operated at either 12.2 cm (2.45 GHz) or 32.7 cm (915 MHz). However, some other frequencies are also available for heating [1]. Most common domestic microwave ovens utilize the frequency of 2.45 GHz, and this may be a reason that all commercially available microwave reactors for chemical use operate at the same frequency. 

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