In geometry, a set of points are collinear to each other if they lie on a single line.

In telecommunications, when two or more dipole antennas are vertically stacked in such a way that their corresponding elements are parallel and collinear with each other, it is called a collinear antenna array. The antennas are mounted in such a way that every element of each antenna is in an extension of other antenna stacked upon it.

The antennas are linked in such a way that the radiating dipoles sum up all radiation intensities. 180° phase shifting is used between the dipoles to prevent destructive sums.

Collinear antenna arrays usually operate in the 30 MHz to 3GHz frequency bands, providing enhanced gain and directivity. They increase the power radiated and provide highly directional beam.