antenna array working at

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

Optimizing half-wave sloper arrays for 160 meters - This article presents a 160-meter variation of this family of antennas and, more importantly, a discussion of the details of how to get such a beast working really well.