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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.

Questions & Answers

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
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 ?
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.
is Bucky paper clear?
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.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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
what is system testing
what is the application of nanotechnology?
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
anybody can imagine what will be happen after 100 years from now in nano tech world
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
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
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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