Stacking Principles

 Stacking with Coax Stacking with Power Splitters

Fundamental Knowledge for Stacking (by DK7ZB)

Stacking of antennas is a method for increasing the gain by decreasing the radiation angles. Thereoretically the additional gain for a second Yagi  with optimal stacking distance is 3 dB (exception: Dipole and 2-El.-Yagi 4 dB). The  stacking distance depends on the radiation angles (azimuth and elevation) of each single Yagi. As a rule of thumb take the stacking distances for vertical stacking of horizontally polarized Yagis in the picture below. All pictures show examples for 2m-Yagis, but the basics are for all frequencies.

The picture shows the distance for two optimized Yagis for 3 dB stacking gain.

The gain (dBd) of a single Yagi versus the stacking distance (lambda).

With that distance you are always very close to the optimal data.

With lower distance you get lower gain, but mostly a pattern with less sidelobes. If the Yagis come to close together, the impedances of the Yagis will change, you should avoid that!

The 4x8-El.-28-Ohm-Yagis of Emmanuel, F4DSD

This is the best configuration for point-to-point communication like EME and MS. Both radiation angles (vertical and horizontal) are smaller than with a single Yagi. The pattern is similar to a single Yagi with a 4-times longer boom.

The 4x5-El.-28-Ohm-Yagis of  DL0BL

This is the recommended stacking method for Contest-operating and own cq-calls: Small vertical angle and great horizontal angle.

Solution for the "one-man-operation":

Two lightweight Yagis vertically stacked.

Here the narrow band 6-El.-50-Ohm-Yagi, gain with stacking losses 13 dBd. The description of the Yagi in the chapter "Lightweight Yagis", but here with a boom 16x1 mm of aluminium (not PVC).