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A Frequency Selective Surface (FSS) is any surface construction designed as a 'filter' for plane waves. FSS characteristics are Narrow Band, periodic in two dimensions.
Frequency selective surfaces (FSS) has become an alternative to the fixed frequency metamaterial; where static geometries and spacings of unit cells determine the frequency response of a given metamaterial. Because arrayed unit cells maintain static positions throughout operation, a new set of geometrical shapes and spacings would have to be embedded in a newly fabricated material for each different radiated frequency and response. Instead, FSS based metamaterials allow for optional changes of frequencies in a single medium (metamaterial) rather than a restriction to a fixed frequency response.
Frequency selective surfaces can be fabricated as planar 2-dimensional periodic arrays of metallic elements with specific geometrical shapes, or can be periodic apertures in a metallic screen. The transmission and reflection coefficients for these surfaces are dependent on the frequency of operation and may also depend on the polarization and the angle of the transmitted electromagnetic wave striking the material or angle of incidence. The versatility of these structures are shown when having frequency bands at which a given FSS is completely opaque (stop-bands) and other bands at which the same surface allows wave transmission.
FSS was first developed to control the transmission and reflection characteristics of an incident radiation wave. This has resulted in smaller cell size along with increases in bandwidth and the capability to shift frequencies in real time for artificial materials.
ADIL ZAMAN BABAR
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What is the difference between selective and nonselective catheter placement?
Selective catheter placement involves guiding a catheter to a specific target area within the body, such as a particular blood vessel or organ. Nonselective catheter placement, on the other hand, does not have a specific target and may involve placing a catheter in a more general location within the body, such as a vein or artery. Selective placement is often used for targeted procedures, while nonselective placement may be used for more general purposes like fluid administration or monitoring.
What are three common examples of frequency division multiplexing?
AM radio broadcasting uses frequency division multiplexing to allocate different frequencies to different radio stations. Cable television systems use frequency division multiplexing to transmit multiple channels simultaneously over a single cable. Cell phone networks use frequency division multiplexing to separate different users' calls on the same frequency band.
What does fsk stand for?
FSK stands for Frequency Shift Keying, a method used in communication systems to encode information by varying the frequency of a carrier signal.
Which theorist is associated with the idea that information moves from sensory memory to short-term memory through the processes of selective attention?
Donald Broadbent first theorized this selective attention theory after working with air traffic controllers during the war. He theorized that a sensory buffer operates where sensory inputs that were not processed decayed rapidly and were lost.
What two major theories that attempt to explain hearing are?
Two major theories that attempt to explain hearing are the frequency theory and place or resonance theory. The frequency theory was also called the telephone theory at times during the early stages.
What is selective amplifier?
Selective amplifier is an RF amplifier which selects particular frequency and amplifier so it can operate at fixed frequency.
What is the function of intermediate frequency transformer?
intermediate frequency transformer (ift) acts as a band selective n/w. the ift which is 455 khz is then given to IF amplifiers which is then given to detector.
What has the author Colin M Moore written?
Colin M. Moore has written: 'Reconfigurable frequency selective surfaces'
What has the author David Stuart Lockyer written?
David Stuart Lockyer has written: 'Reconfigurable and closely coupled frequency selective surfaces'
What is meant by frequency Interleaving?
Frequency interleaving is a technique where consecutive symbols in a data stream are spread across different frequency subcarriers in a communication system. This helps combat frequency-selective fading in wireless channels by reducing the impact of frequency-specific signal impairments. By spreading the symbols across multiple frequencies, frequency interleaving helps improve robustness and reliability of the communication link.
When a mutation first occurs a different allele is formed what best describes the frequency of this allele?
When a mutation first occurs, the frequency of the new allele is very low in the population. Over time, if the allele confers a selective advantage, it may increase in frequency through natural selection.
What is the difference between flat and selective fading?
Flat fading, or nonselective fading, is that type of fading in which all frequency components of the received signal fluctuate in the same proportions simultaneously. Selective fading affects unequally the different spectral components of a radio signal.
How is the threshold frequency related to work function?
The threshold frequency is the minimum frequency of light required to eject electrons from a metal surface (photoelectric effect). The work function is the minimum energy needed to remove an electron from the metal surface. The threshold frequency is directly related to the work function through the equation E = hf, where E is the energy, h is Planck's constant, and f is the frequency.
How do these selective pressures affect the genetic variation in the population?
Selective pressures can impact genetic variation by favoring certain traits or alleles while reducing the frequency of others in a population. Strong selective pressures can lead to genetic changes over generations as individuals with advantageous traits are more likely to survive and reproduce. Conversely, weak or fluctuating selective pressures may allow for higher genetic variation to persist within a population.
Why series resonance is termed as selective circuit?
Because they can be used to obtain or get an output (on a series connected resistance with them) for a specific frequency of the input signal. This is the ideal case, but in fact, the resonance circuit passes a band (not a single frequency) of input signals' frequencies to take them at the output terminal. They are also termed as ( filters or filtering circuits ). They are called selective as they function as if they select signals of specific frequencies to be passed to the output.
Are surface waves higher or lower frequency than body waves?
Surface waves have lower frequency than body waves. Surface waves travel along the Earth's surface and cause the ground to shake in a rolling motion, while body waves travel through the Earth's interior and can travel at higher frequencies.
What is selective reflection?
Selective reflection refers to the process in which certain wavelengths of light are selectively reflected off a surface, while others are absorbed or transmitted. This phenomenon is responsible for the colors we perceive when light interacts with different materials. The selective reflection of specific wavelengths gives objects their color appearance to the human eye.
