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Two full peaks but at different locations

If you consider the peaks at the ends of the wavenumber response for the leftmost and center images in Figure 3 to each represent only half a peak (with the other half being off the scale to the left and the right) , all three scenarios have two complete peaks in their wavenumber responses.

(You could think in terms of printing the wavenumber response on a piece of paper, cutting it out, and taping the two ends together to form acontinuous ring. As you made a complete traversal of the ring, you would encounter two peaks.)

However, the locations of the two peaks for the rightmost array are at completely different wavenumber values than are the peaks for the other twoarrays. The two peaks exhibited by the rightmost array are in the locations of the two nulls for the center array. Similarly, the null points for the rightmostarray are in the same locations as the two peaks for the center array.

What can we learn from these scenarios?

We learn that we can have a significant impact on the wavenumber response of an array by increasing the number of elements in the array. We can also have asignificant impact on the wavenumber response by applying weights, (including sign changes) , to the electrical signals produced by the array elements before adding them together.

Extending into two dimensions

Now let's complicate things a bit by extending our array analysis into two dimensions. Up to this point, we have assumed that our sensors were attached toa wire that was free to move up and down only. As such, waves impinging on the array were constrained to approach the array from one end or the other. In thiscase the wavenumber was completely determined by the wavelength of the wave.

(For our purposes, the wavelength is given by the ratio of propagation speed in meters per second to frequency in cycles per second.Canceling out the units leaves us with wavelength in meters per cycle.)

Move the array to a table top

Let's move our array of sensors from the wire to a large sheet of metal on the top of a table. For the time being, we will still place the elements in aline with uniform spacing. However, we will now assume that a wave can impinge on the array from any direction along the surface of the sheet of metal.

(For simplicity, we will assume that there is some sort of insulation between the sheet of metal and the table top to prevent waves from impinging on the array from below.)

What does a wave look like in this scenario?

Imagine a piece of corrugated sheet metal or fiber glass. (Material like this is sometimes used to build a roof on a patio.) When you look at it from one end, it looks something like the sine wave in Figure 1 . However, if you keep it at eye level and slowly turn it in the horizontal plane, the distance between the peaks willappear to become shorter and shorter until finally you don't see any peaks at all. What you see at that point is something that appears to have the samethickness from one end to the other. This is the view that one of our sensors sees as the wavefront of an impinging wave.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
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