Basics of Collinear Antenna

• The collinear antenna is most commonly found these days as a vertical antenna with several elements stacked above each other.
• It can also be used as a horizontal antenna. It could be considered very broadly as a directive form of the dipole.
• The basic idea is that several antenna elements that are arranged along the same axis are fed with the signal.
• A Collinear array consists of two or more half-wave dipoles, which are placed end to end. These antennas are placed on a common line or axis, being parallel or collinear.
• The maximum radiation in these arrays is broadside and perpendicular to the line of the array. These arrays are also called broadcast or Omni-directional arrays.
• The frequency range in which the collinear array antennas operate is around 30 MHz to 3GHz which belong to the VHF and UHF bands.
• A collinear antenna array (sometimes colinear antenna array) is an array of a dipole or quarter-wave antennas mounted in such a manner that the corresponding elements of each antenna are parallel and collinear; that is, they are located along a common axis.
• The antenna structure recalls the use of Franklin’s principle in linking several radiating dipoles, to sum up, all radiations’ intensities.
• Using 180° phase shifting between the dipoles to prevent destructive sums, the antenna can be implemented with other types of antenna dipoles such as microstrip patch antenna.

• All dimensions are in mm. The schematic shows only the linking between two of the three dipoles: The second link being exactly built in the same manner.

Solids and Materials

• The feed of the antenna is located on the lateral face of one of its ends; the other end is an open circuit.
• Each dipole is treated like an insulating layer of Duroid 5880 substrate with PEC inner and outer conductor layers. All dipoles are plunged into an air box whose lateral surfaces simulate an anechoic chamber.