Antennas and Wave Propagation

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Q1) What is an Antenna ?

Ans: An Antenna is a transducer,i.e, it converts electrical signals to Electromagnetics Wave at the transmitter and vice versa at the receiver.
An Antenna is a sensor and radiator of EM waves.
An Antenna is a perfect impedance matching device.
Any piece of conducting material or wire acts as an Antenna on excitation.

Q2) What is a Isotropic radiator ?

Ans: It is an Antenna which radiates equally in all directions. It is also called as reference antenna.

Q3) What is a Omni Directional Antenna ?

Ans: It radiates equally in all directions in azimuthal plane and radiates in single direction in elevation plane.

Q4) Name some of the Antenna Parameters ?

Ans: some of the Antenna parameters are as follows:

1. Antenna Impedance
2. Radiation pattern
3. Radiation Intensity
4. Directive Gain
5. Power Gain
6. Efficiency
7. Effective area
8. Front to Back ratio
9. Antenna Bandwidth

Q5) What is a Radiation Pattern ?

Ans: Radiation pattern is the variation of electric field strength with respect to elevation angle.

Q6) What is Radiation Intensity ?

Ans: It is the radiated power per unit solid angle.

Q7) What are the units of Solid angle ?

Ans: Steradian

Q8) What is the effective length of an Antenna ?

Ans: It is the length of Antenna which is responsible for transmission or reception of EM waves.
It is always less than the actual length of an Antenna.

Q9) What is Antenna Bandwidth ?

Ans: It is the range of frequency over which antenna will perform satisfactory without any change.

Q10) What is Antenna Arrays ?

Ans: It is the system of Antennas similarly oriented or dis similarly oriented to achieve maximum gain or directivity.

Q11) What are advantages of Antenna Arrays ?

Ans: Advantages:

1. Enhancement in gain
2. Enhancement in directivity
3. Reduction in Beam width

Q12) What are disadvantages of Antenna Arrays ?

Ans: Disadvantages:

1. Side lobes increases
2. Cost increases
3. complexity increases
4. more space is required for installation

Q13) What is a Broad side Array ?

Ans: If the principal maxima or Radiation pattern is perpendicular to axis of array then it is Broad side array.

Q14) What is End fire Array ?

Ans: If the principal maxima or Radiation pattern is along the axis of array then it is Broad side array.

Q15) What is Front to Back ratio in Antennas ?

Ans: It is the ratio of radiation in desired direction to that of radiation in opposite direction. For an ideal Antenna it is infinity.