Frequently Asked Questions On Antenna Theory With Answers - 8.


This page contains basic questions and short notes on some of the keywords on antenna theory:


36) Define beam width of major lobe?

It is defined the angle between the first nulls (or) it is defined as twice the angle between the first null and the major lobe maximum direction.


37) List out the expression of beam width for broad side array and end fire array?

For broad side array the expression for beam width between the first nulls is given by,

BWFN = ( ( + / -) 2 λ / n d )

For End fire array the expression for beam width between the first nulls is given by,

BWFN = ( ( + / -) 2 ( 2 λ / n d ) )1/2


38) Differentiate broad side and End fire array?

  • In Broad side array antennas are fed in phase δ = 0, where as in end fire arrays the antenna elements are fed out of phase i.e. δ = - β d.
  • In broad side array the maximum radiation is perpendicular to the direction of array axis, where as in case of end fire array the maximum radiation is directed along the array axis.



39) What is the need for the Binomial array?

The need for a binomial array is

  • In uniform linear array as the array length is increased to increase the directivity, the secondary lobes also occurs.
  • For certain applications, it is highly desirable that secondary lobes should be eliminated completely or reduced to minimum desirable level compared to main lobes.



40) Define power pattern?

Graphical representation of the radial component of the pointing vector Sr at a constant radius as
a function of angle is called power density pattern or power pattern.


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