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Could continue adding elements tothe array

Although I won't demonstrate it, I can tell you that if I were to continue adding elements in this manner to increase the length of the array, the centralpeak and the peaks at the folding wavenumbers would continue getting narrower, and the trough between the peaks would continue getting deeper and probablyflatter.

A more selective wavenumber filter

In other words, when viewed as a wavenumber filter, a long array with more elements is a moreselective wavenumber filter than a short array with fewer elements. By properly designing an array to act as a wavenumber filter, it is possible to cause that filter to be veryselective.

When we use a properly designed array to produce a directional antenna, it is possible to produce a highly directional antenna (and avoid wasting our valuable radio frequency energy by sending it to cows and cotton plants).

A weighted three-element array

Continuing with our three-element array scenario, let's take a look at the center pair of images in Figure 3 and compare them with the leftmost images in Figure 3 .

For this case, the array still contains three elements with the same spacing as before. However, the electrical output from the center element is amplifiedto make it twice as strong as the outputs from the other two elements before the three electrical signals are added together.

Note that the array elements are no longer shown as being white against a black background in the very top of the top-center image. Instead, thecenter element is white but the other two elements are greenish indicating different weights.

It is a little hard to tell what this does to the central peak in the wavenumber response, but it definitely changes the shape of the response in thetrough between the peaks. Whether or not this would be a beneficial change would depend on the problem being addressed.

A three-element array with negative weighting

Finally, take a look at the rightmost pair of images in Figure 3 . Once again, the array contains three elements and the center element is weighted twice asheavily as the other two. In addition, the sign of the electrical signals from the two outer elements is inverted before the three are added together.

Note that the black color represents the smallest algebraic value. Negative values are smaller than positive values. Therefore, the background(which represents a weigh of zero) has changed from black to something between green and blue. The two elements withthe negative weights are shown as black and the element with the positive weight is shown as white.

The wavenumber response

This has a major impact on the wavenumber response of the three-element array.

There is no longer a peak at a wavenumber value of zero. Rather, there is now a null point at zero wavenumber as indicated by the black and blue colors at thecenter of the plot. There is now a peak on each side of zero (as indicated by the white and red colors) , half way between zero and the folding wavenumber.

Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
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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