antenna collinear array

Directional arrays - About collinear array antennas

Definition of Collinear antenna array - Wikipedia page about collinear antenna arrays

BiQuad Antenna for 144/440 - This is a vertically polarized Broadside and Collinear Array each Loop is a vertically polarized Broadside Array both the right and the left side of the Loop is a bent 1/2 wave dipole working 180 degrees out of phase with the other one and that gives you 4.15dbi of gain by KE4UYP