This is a pair of KLM 16LBX 28 foot yagis mounted on a Polar mount in my back yard. The yagis are shown in their vertical polarized position but they are motorized to adjust the polarization to any angle between zero and 90 degrees.
Here the antennas are rotated to -45 degrees to track the moon. The declination is set to -7 degrees. Note the 5 foot piece of pipe extending downward between the antennas. This is a handle and a measuring device. It is clamped so as to be vertical when the antennas are at zero degrees declination. To set declination I loosen the clamps holding the cross boom and then adjust the angle of the handle using a magnetic mount inclinometer. Details of cross boom mounting
A closer view of the base. The mount is made from an 8 foot section of Rohn 45 tower and a 20 foot section of aluminum tower. The Aluminum tower is the polar mount. It is tilted at an angle of 39.5 degrees and pointed due north.
Below is a view of the mounting for one antenna. The gusset plates are 3/8 inch aluminum by 3 inches wide. The bearings are made from 1/2" Yellow Pine, turned to a diameter approximately .100 inch larger than the diameter of the antenna boom. Also note the clamp at the right side of the picture that attaches the polarization rotation arm.
A view of the other antenna mounting, showing the antennas rotated to about 45 degrees.
You can just see part of a round clamping collar that is attached to the boom between the right hand bearing (above) and the polarization rotation arm. It keeps the antenna from sliding down and causing the rotation clamp to rub on the bearing. One is not needed at the other end because the antennas always point up! Details on the bearings, rotation arm, and clamps.