# 4.6 Java1490-2d fourier transforms using java, part 1  (Page 4/15)

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## Where people live

Your town has a small business district at the intersection of the two highways. Beyond that, most of the people who live in your town (and who will listen to your radio station ) live along the two highways. Thus most of the population lives in the directions of northeast, southwest, northwest, andsoutheast from the center of town. There are very few people living in the directions of north, south, east, and west. That real estate is mostly populatedby cows and cotton fields.

## A limit on the transmitting power

Your new FCC license places a limit on the amount of power that you will be allowed to transmit. You would like to use that available powerto reach a many human listeners as possible. If you simply construct an omnidirectionaltransmitting antenna and start broadcasting, approximately half of the power that you transmit will be available mostly to cows and cotton plants. As aresult, the amount of power, and hence the reach of the power that you transmit to human listeners will be less than you would like for it to be.

## A directional transmitting antenna

While the FCC won't allow you to increase the amount of power that you transmit, they will allow you to control the directions in which you choose totransmit that power. You will probably hire an expert in the transmission of radio signals to design a directional transmitting antenna system, which willbroadcast most of the available power in the directions where the people live. Ideally, the antenna system will transmit very little of the available power inthe directions of the cows and the cotton fields.

## The design of the antenna system

The antenna designer will have many tools at her disposal. Whether or not she uses wavenumber terminology, many of the calculations that she performs willdepend on wavenumber concepts. She will be concerned about the reciprocal wavenumber (wavelength) of the radio signals that will be broadcast. She will be concerned with the lengths of the active elements in the antenna system, andthe distance between active elements if she chooses to use an array of active elements.

## Basic concepts

I will leave the radio station scenario at this point and discuss some more basic concepts. I will return to the radio station scenario later. We will needto start with simpler things and work our way up to the radio station scenario.

Much of this discussion will be couched in terms of receiving signals rather than transmitting signals. (For most people, receiving is easier to understand than transmitting.) However, most of the conclusions that we reach regarding antenna systems used for receiving signals are also applicable to antennasystems used for transmitting signals.

## A one-dimensional space

Just to get us started down the right path, we will temporarily constrain space to have only one dimension. We will discuss the propagation of waves alonga taut wire, as well as the measurement of the waves propagating along that wire.

Assume that a wire is fastened at both ends, is fairly taut, and is suspended between two walls so that it is free to move up and down only. Assume that weattach two sensors to the wire, one meter apart, and that each of these sensors is capable of generating an electrical signal that is proportional to thevertical displacement of the wire at the point where the sensor is attached. If the wire goes up, the sensor generates a positive signal. If the wire goes down,the sensor generates a negative signal.

what does nano mean?
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?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
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
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?
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 ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
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
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
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.
what is nano technology
what is system testing?
preparation of nanomaterial
how did you get the value of 2000N.What calculations are needed to arrive at it
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