An array of dipoles can be fed to achieve an end-fire pattern.
If the phase of the current on each element is equal, the array will have maximum radiation broadside to the array. If the phase of the currents is equal to the physical spacing of the elements, then the array radiates from its end.
An attempt to show this is shown here:
The three circles represent the dipoles, and the three waves are the electric fields radiated by them. To the right, the waves all add in phase, this is the direction of maximum radiation. To the left, they do not add in phase, and the pattern is smaller. (in fact, with three dipoles, this isn't the optimum phasing for best front-to-back, but for larger arrays this is less important)
How should such an array be fed, to ensure the currents are as required for end-fire radiation?