Antenna Theory Collinear Array - Antenna Theory

What is Antenna Theory Collinear Array?

A Collinear array contains of two or more half-wave dipoles, which are located end to end. These antennas are located on a common line or axis, being parallel or collinear.

The maximum radiation in these arrays is broad side and perpendicular to the line of array. These arrays are also called as broad cast or Omni-directional arrays.

Frequency range

The frequency range in which the collinear array antennas operate is around 30 MHz to 3GHz which belong to the VHF and UHF bands.

Construction of Array

These collinear arrays are uni-directional antennas having high increase. The key drive of this array is to raise the power radiated and to afford high directional beam, by evading power loss in other directions.


construction_array

The above pictures show the pictures of collinear arrays. In figure 1, it is seen that collinear array is designed using folded dipoles, while in figure 2, the collinear array is formed by normal dipoles. Both types are half-wave dipoles used normally.

Radiation Pattern

The radiation pattern of these collinear arrays is related to that of a single dipole, but the array pattern of increasing number of dipoles, makes the difference.


collinear_radiation_pattern

The radiation pattern of collinear array while made using two elements, three elements and four elements individually are shown in the figure given above.

The broad side array also has the same pattern, in which the direction of maximum radiation is perpendicular to the line of antenna.

Advantages

The resulting are the advantages of collinear array antennas −

  • Use of array reduces the broad ends and increases the directivity
  • Minor lobes are minimised
  • Wastage of power is reduced

Disadvantages

The resulting are the disadvantages of collinear array antennas −

  • Movement of these antennas is a difficult task
  • Used only in outdoor areas

Applications

The resulting are the applications of collinear array antennas −

  • Used for VHF and UHF bands
  • Used in two-way communications
  • Used also for broadcasting purposes

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