FIELD THEORY OF GUIDED WAVES PDF
Browse Books > Field Theory of Guided Waves. . Quick Abstract | Full Text: PDF file icon PDF. This chapter contains sections titled: The Probe Antenna. Field Theory of Guided Waves - resourceone.info - Ebook download as PDF File .pdf), Text File .txt) or read book online. Field theory. Packed with examples and applications FIELD THEORY OF GUIDED WAVES provides solutions to a large number of practical structures of current interest.
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Electrical Engineering/Electromagnetics Field Theory of Guided Waves Second Edition A volume in the IEEE/OUP Series on Electromagnetic Wave Theory. Research papers on 2DEG Systems in the Terahertz frequency domain - hasantahir/Sommerfeld-Research. Results 1 - 17 of 17 Basic Electromagnetic Theory. Robert E. Collin. Request permission for reuse | Click to expand Abstract | PDF file icon PDF (KB).
He even designed an experiment to show that if you hold on to realism — in which quantum objects such as photons always have definite, intrinsic properties, a position that encapsulates a more classical view of reality — then one is forced to concede that the future can influence the past. They gave the dragon a well-defined body, but one that is hidden from the mathematical formalism of standard quantum mechanics.
With unusual alacrity, three teams raced to do the modified experiment.
Their results, reported in early June , have shown that a class of classical models that advocate realism cannot make sense of the results.
Dragon Trap Wheeler devised his experiment in to highlight one of the dominant conceptual conundrums in quantum mechanics: wave-particle duality.
Quantum objects seem to act either like particles or waves, but never both at the same time. This feature of quantum mechanics seems to imply that objects have no inherent reality until observed.
In the experiment, a single photon is fired at a half-silvered mirror, or beam splitter. The photon is either reflected or transmitted with equal probability — and thus can take one of two paths. In this case, the photon will take either path 1 or path 2, and then go on to hit either detector D1 or D2 with equal probability. The photon acts like an indivisible whole, showing us its particle-like nature. At the point where path 1 and path 2 cross, one can add a second beam splitter, which changes things.
In this setup, quantum mechanics says that the photon seems to take both paths at once, as a wave would. The two waves come back together at the second beam splitter. The experiment can be set up so that the waves combine constructively — peak to peak, trough to trough — only when they move toward D1.
The path toward D2, by contrast, represents destructive interference. In such a setup, the photon will always be found at D1 and never at D2.
Project Control: Integrating Cost and Schedule in Construction
Here, the photon displays its wavelike nature. It should act like a particle. One can, however, add the second beam splitter at the very last nanosecond. Both theory and experiment show that the photon, which until then was presumably acting like a particle and would have gone to either D1 or D2, now acts like a wave and goes only to D1. To do so, it had to seemingly be in both paths simultaneously, not one path or the other.
One way to avoid such retro-causality is to deny the photon any intrinsic reality and argue that the photon becomes real only upon measurement. That way, there is nothing to undo. His team wanted to explain counterintuitive aspects of quantum mechanics using a new set of ideas called causal modeling, which has grown in popularity in the past decade, advocated by computer scientist Judea Pearl and others. Causal modeling involves establishing cause-and-effect relationships between various elements of an experiment.
In such cases, causal modeling can help uncover C. But they were in for a surprise. The task proved relatively easy. The experimenter then chooses to add or remove the second beam splitter. Here was a classical, causal, realistic explanation. They had found a new loophole. It is seen that the bare Salisbury screen only produces one RCS reduction dip around 15 GHz, while there is no obvious RCS reduction dip for the 1D grating structure in the whole frequency band of interest.
However, after integrating 1D grating structure with Salisbury screen, the two RCS reduction dips are respectively generated at 4. Figure 2 Full size image To further understand the physical mechanism of the designed RCS reduction structure, its scattering patterns at 4. It is seen in Fig. At the frequency of 16 GHz, a series of high orders reflection beams are generated and redirected to various directions due to the grating period far larger than the operating wavelength.
However, the whole high-order reflection efficiency is relatively weak compared with that at 4. The power loss density distributions of our structure are also examined, as seen in Fig.
Robert E. Collin
It is obvious that very strong power loss is focused on the lossy sheet layer at 16 GHz, while the power loss is relatively weak at 4. Therefore, we can deduce that the Salisbury screen plays the leading role in the backward scattering reduction at 16 GHz by absorbing the most of the incident wave energy. The main reason for the generation of the RCS reduction dip at 4. In addition, the lossy graphene layer can also absorb part of the incident wave energy, as seen in Fig.
So we consider that the RCS reduction dip at 4. Figure 3 Full-wave simulation results of the proposed 1D grating integrated Salisbury screen under normal incidence of EM waves. The 3D scattering pattern at a 4.
The power loss density distributions at c 4. Full size image It is worthwhile to point out that between the two RCS reduction dips, there is still a broad band in which the RCS reduction level is less than 10 dB for the 1D grating integrated Salisbury screen. In order to solve this issue, we use the two-dimensional 2D grating structure instead of the 1D grating structure in our design, as seen in Fig.
The period along x direction Px is equal to the period along y direction Py. Therefore, the electromagnetic response would be polarization independent due to its symmetry structure. It is seen that its 10 dB RCS reduction bandwidth is obviously increased, which is expanded from 4. It may be due to that the 2D grating structure has higher diffraction efficiency and can generate high order reflection in both yoz and xoz planes, compared with the 1D grating structure.
That is to say, the minimum requirement for the grating cells is only two periods in our design. It is seen that the high-order reflection beams are only generated in xoz plane, and then the backward reflected wave is still strong.
After employing the 2D grating structure, the high-order reflection beams can be simultaneously produced in both xoz and yoz plane, so the normal reflection of the incoming wave can be further suppressed, as seen in Fig. It is seen that the RCS reduction bandwidth decreases a little under TM mode with the increase of the incident angle. As the effective sheet resistance of graphene can be tuned through an applied electrostatic field bias 26 , the tunable RCS reduction performance could be expected for our structure.
As Fig. The original two RCS reduction dips occurring at 4. That means the graphene resistance of the Salisbury screen has great influence on the RCS reduction level. Figure 6 Simulated RCS reduction performance of the designed 2D grating integrated Salisbury screen with the different graphene resistances. The graphene film is grown on copper foil using the chemical vapor deposition method and then transferred onto the PET film.
The thin silver fabricated with screen printing technique at the edges of the graphene samples stripes serve as contact metals. In the fabrication process, the large-area graphene-coated PET film and the high-resistance sheet serve as the two electrodes of the graphene structure, respectively.
When applying the DC bias voltage on the graphene structure, the doping level of the graphene film would be controlled, resulting in the change of the surface resistance. Here, the fabricated graphene structure is used as the lossy sheet of Salisbury screen, while the high-index grating structure is made of aluminum oxide.
The graphene structure is bonded with the grating structure through the glue film, and then attached to a 5 mm-thick PMI foam slab backed by a metal plate. Figure 7 Photograph of measurement setup for the fabricated sample and its corresponding measurement results. Full size image We measured the reflectivity of the fabricated sample by using arch measurement system 30 in the microwave anechoic chamber, as shown in Fig. The two linearly-polarized horn antennas are placed on an arch range and the sample is located in its center.
Therefore, we have demonstrated that our sample can achieve dynamical control of the reflection over a wide frequency band. For the TE polarizations, it is seen in Fig. The above measured results indicate our sample has a good angular stability.
Full size image Discussion In summary, the hybrid physical mechanism has been utilized to achieve broadband RCS reduction. By integrating high-index dielectric grating structure with the traditional Salisbury screen, both the absorptive loss and radiative loss are generated in our design.
The high-index dielectric grating structure can produce lots of high-order reflections, and then deflect the incoming wave direction. The Salisbury screen can further absorb the incident wave energy. By tuning the surface resistance of the graphene layer that is the lossy sheet of the Salisbury screen, the RCS reduction level can be dynamically controlled. Our structure has been experimentally demonstrated to realize the 10 dB RCS reduction over a wide frequency band ranging from 4.
In addition, the tunable RCS reduction performance can be achieved by changing the DC bias voltages applied on the graphene layer.Integrating Cost and Schedule in Construction. For the rectangular waveguide problem the Green's function can be expressed as an inverse Fourier transform in the form 1 1 When E and J.
Figure 1 Schematic of the proposed RCS reduction structure and its simulated reflection coefficients. Nevertheless, most important elements of guided-wave optics are covered in this book. Show that A is a solution of the vector Helmholtz equation.
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