Teardown of a Kathrein Dual Panel 1800/900 MHz used for both GSM (2G) and 3G mobile broadband technologies. It also has options for Remote Electrical Tilt (RET). On the inside we will find phase changers, splitters, combiners and 1800/900 MHz antenna elements. I give a walk-through of the circuit, what the different elements does and what kind of antenna design it is based upon.
The input signal goes through a signal splitter where the 1800 and 900 MHz signals are splitted or combined.
The base / back plate of the Kathrein antenna is based on the slanted sidewall principle.
The antenna array consists of both 1800 and 900 MHz elements. Some elements are static and some are fed through the remote electrical tilt option. Therefore it is able to change the shape of the antenna lobe.
The Remote Electrical Tilt function (RET) is a simple motor adjusting a isolated rod to the phase shifter mechanism, that can change phasing of the signal by 15 degrees.
The coaxial wiring is made from silvered wire and kept in either red or white insulating material to distinguish between the 1800 and 900 MHz signals. All wires have special impedances, especially for the job inside the antenna. The reason for long and bent cables are to match impedances between different wires and avoid unwanted phase shifting.