Antenna Theory - Colpnear Array

A Colpnear array consists of two or more half-wave dipoles, which are placed end to end. These antennas are placed on a common pne or axis, being parallel or colpnear.

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

Frequency range

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

Construction of Array

These colpnear arrays are uni-directional antennas having high gain. The main purpose of this array is to increase the power radiated and to provide high directional beam, by avoiding power loss in other directions.

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

Radiation Pattern

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

The radiation pattern of colpnear array when made using two elements, three elements and four elements respectively 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 pne of antenna.

Advantages

The following are the advantages of colpnear array antennas −

Use of array reduces the broad ends and increases the directivity

Minor lobes are minimised

Wastage of power is reduced

Disadvantages

The following are the disadvantages of colpnear array antennas −

Displacement of these antennas is a difficult task

Used only in outdoor areas

Apppcations

The following are the apppcations of colpnear array antennas −

Used for VHF and UHF bands

Used in two-way communications

Used also for broadcasting purposes