EC 2401 Wireless Communication Study Materials

Dear Students ,

Herewith i have attached the required study materials for EC 2401 - Wireless Communications for all units. The Lecture PPTs may Help you in understanding the concepts in different perspective.

Click on the below link to Download.

Lecture Notes:

Unit 1 - Services and Technical Challenges (Will be Uploaded Shortly)

Unit 2 - Wireless Propagation Channels (Will be Uploaded Shortly)

Unit 3 - Wireless Transceivers (Will be Uploaded Shortly)

Unit 4 - Signal Processing in Wireless Systems (Will be Uploaded Shortly)

Unit 5 - Advanced Transceiver Systems (Will be Uploaded Shortly)

Lecture PPT's:

Unit 2

Unit 3

Unit 4

Unit 5

Other Useful Files for preparation:

Previous Year Ques Papers

Unit Wise Ques Bank

Anna University Syllabus - Department of Electronics and Communication Engineering

Dear Students, Here is the syllabus for Department of ECE

Regulation 2008 (Sem 2 to 8)

Regulation 2013 (Sem 1 to 8)

OHMS LAW

Ohm's Law

Combining the elements of voltage, current, and resistance, Ohm developed the formula:

Where

·         V = Voltage in volts

·         I = Current in amps

·         R = Resistance in ohms

This is called Ohm’s law. Let’s say, for example, that we have a circuit with the potential of 1 volt, a current of 1 amp, and resistance of 1 ohm. Using Ohm’s Law we can say:

Let’s say this represents our tank with a wide hose. The amount of water in the tank is defined as 1 volt and the “narrowness” (resistance to flow) of the hose is defined as 1 ohm. Using Ohms Law, this gives us a flow (current) of 1 amp.

Using this analogy, let’s now look at the tank with the narrow hose. Because the hose is narrower, its resistance to flow is higher. Let’s define this resistance as 2 ohms. The amount of water in the tank is the same as the other tank, so, using Ohm’s Law, our equation for the tank with the narrow hose is

But what is the current? Because the resistance is greater, and the voltage is the same, this gives us a current value of 0.5 amps:

So, the current is lower in the tank with higher resistance. Now we can see that if we know two of the values for Ohm’s law, we can solve for the third. 

ATOMIC THEORY OF ELECTRONICS

Basics of Electronics:

When we speak about electronics, first few terms that strikes in our minds are CURRENT, VOLTAGE, ENERGY Etc., Every Electronic Engineer would say the famous definition of current “Flow of electrons is called as current” but very few gets deeper in to it and raises a question - how it is said that movement of electrons are referred to as current, and these few people gets success in engineering.

What is electronics?

                The branch of physics and technology concerned with the design of circuits using some electronic components with the behavior and movement of electrons in a semiconductor, conductor, vacuum, or gas.

            To understand more about the electronics we must learn the very basics of electrons like, from where the electron came from and some concepts behind the electrons.

ATOMIC STRUCTURE:

                All the materials are composed of very small particles called atoms. Large number of atoms makes a matter or substance. One single atom consists of central Nucleus of positive charge around which the small negatively charged particles called Electrons revolve in different paths or orbits.

Components of an Atom

1.   Nucleus: contains Protons and Neutrons

            Protons: They are the positively charged particles

            Neutrons: They have the equal mass of protons, but have no charge (Neutral)

Hence the Nucleus is positively charged in nature.

2.   Electrons: It is the outer part of the atom which revolves around the nucleus. Electrons have the negligible mass compared to the protons and neutrons. They have the same amount of charge as proton but with opposite polarity (Negative)

In an atomic structure number of protons is equal to the number of electrons.

The following video shows the visual of how the electrons revolve around the nucleus:

ENERGY OF AN ELECTRON:

            An electron moving around the nucleus possesses two types of energies, they are

1.    Kinetic energy – due to the motion

2.    Potential energy – due to the charge in the nucleus

Total energy of the electron is calculated by the sum of these two energies.

The energy of an electron increases with the distance between the nucleus and electron increases. Which means the electron in the second orbit will have higher energy than the electrons in the first orbit. From this we can infer that the electron at the outer most orbit have the highest energy. The electrons present in the outer most orbits are called as the valance electrons. The maximum number of valance electrons permitted in orbit is 8

This valance electron determines the chemical (solid or liquid or gas) and physical properties (conductor, insulator, semi conductor) of a material.

1.   When the number of valance electrons are less than 4 then the material is said to be a CONDUCTOR

2.   When the number of valance electrons are more than 4 then the material is said to be an INSULATOR

3.   When the number of valance electrons are exactly 4 then the materials are said to be a SEMI – CONDUCTOR

FREE ELECTRONS:

                Free electrons determine the conductivity of a material. The valance electrons which are very loosely attached to the nucleus are called as free electrons.

1.    A conductor has a large number of free electrons.  When a potential difference is applied these free electrons move towards the positive terminal constituting the electric current.

2.    An insulator has no free electrons hence; there is no possibility for electron flow.

3.    A semi conductor has very little number of free electrons, by the level of potential difference this can be used as neither conductor nor insulator as well. 

CONCLUSION:

            Hope you got a better idea on what is electronics. Yes! It is complete study of behavior of electron and the techniques behind controlling the electrons. 

WATER TANK ANALOGY FOR VOLTAGE AND CURRENT

Voltage, Current, & Resistance

Voltage

We define voltage as the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. It is measured in volts, which, technically, is the potential energy difference between two points that will impart one joule of energy per coulomb of charge that passes through it (don’t panic if this makes no sense, all will be explained). The unit “volt” is named after the Italian physicist Alessandro Volta who invented what is considered the first chemical battery. Voltage is represented in equations and schematics by the letter “V”.

When describing voltage, current, and resistance, a common analogy is a water tank. In this analogy, charge is represented by the water amount, voltage is represented by the water pressure, and current is represented by the water flow. So for this analogy, remember:

·         Water = Charge

·         Pressure = Voltage

·         Flow = Current

Consider a water tank at a certain height above the ground. At the bottom of this tank there is a hose.

The pressure at the end of the hose can represent voltage. The water in the tank represents charge. The more water in the tank, the higher the charge, the more pressure is measured at the end of the hose.

We can think of this tank as a battery, a place where we store a certain amount of energy and then release it. If we drain our tank a certain amount, the pressure created at the end of the hose goes down. We can think of this as decreasing voltage, like when a flashlight gets dimmer as the batteries run down. There is also a decrease in the amount of water that will flow through the hose. Less pressure means less water is flowing, which brings us to current.

 Current

We can think of the amount of water flowing through the hose from the tank as current. The higher the pressure, the higher the flow, and vice-versa. With water, we would measure the volume of the water flowing through the hose over a certain period of time. With electricity, we measure the amount of charge flowing through the circuit over a period of time. Current is measured in Amperes (usually just referred to as “Amps”). An ampere is defined as 6.241*10¹⁸ electrons (1 Coulomb) per second passing through a point in a circuit. Amps are represented in equations by the letter “I”.

Let’s say now that we have two tanks, each with a hose coming from the bottom. Each tank has the exact same amount of water, but the hose on one tank is narrower than the hose on the other.

We measure the same amount of pressure at the end of either hose, but when the water begins to flow, the flow rate of the water in the tank with the narrower hose will be less than the flow rate of the water in the tank with the wider hose. In electrical terms, the current through the narrower hose is less than the current through the wider hose. If we want the flow to be the same through both hoses, we have to increase the amount of water (charge) in the tank with the narrower hose.

This increases the pressure (voltage) at the end of the narrower hose, pushing more water through the tank. This is analogous to an increase in voltage that causes an increase in current.

Now we’re starting to see the relationship between voltage and current. But there is a third factor to be considered here: the width of the hose. In this analogy, the width of the hose is the resistance. This means we need to add another term to our model:

·         Water = Charge (measured in Coulombs)

·         Pressure = Voltage (measured in Volts)

·         Flow = Current (measured in Amperes, or “Amps” for short)

·         Hose Width = Resistance

Resistance

Consider again our two water tanks, one with a narrow pipe and one with a wide pipe.

It stands to reason that we can’t fit as much volume through a narrow pipe than a wider one at the same pressure. This is resistance. The narrow pipe “resists” the flow of water through it even though the water is at the same pressure as the tank with the wider pipe.

In electrical terms, this is represented by two circuits with equal voltages and different resistances. The circuit with the higher resistance will allow less charge to flow, meaning the circuit with higher resistance has less current flowing through it.

This brings us back to Georg Ohm. Ohm defines the unit of resistance of “1 Ohm” as the resistance between two points in a conductor where the application of 1 volt will push 1 ampere, or 6.241×10¹⁸ electrons. This value is usually represented in schematics with the greek letter “Ω”, which is called omega, and pronounced “ohm”.