• Tour of WSDZ-AM Tower Site: Today, the author and his dad toured the WSDZ-AM tower site in Belleville, IL. It's a 20kW AM radio station with an array of eight individual towers.
• The Phasor: To get a single coherent signal from the eight-tower array, a phasor is used. It has an "o" and not an "e", different from the "phaser" in Star Trek. Behind the unassuming front panel with cranks are very beefy variable inductors and vacuum capacitors for adjusting the phase, power, and reactance of each tower.
• Phasor Tuning: In addition to the phasor, there are ATUs (Antenna Tuning Units) at the base of each tower to match them to the phasor and transmitter. When there are issues, the engineer calls Phasetek.
• Video and References: There is an entire video embedded below about the tower site, which covers equipment, tower array design, transmitter room layout, etc. An intro video about antenna theory is also recommended. Modern beam-forming antennas have more exotic applications. For controlling the signal's directionality at night, there are 16+ massive RF relays remotely operated. It's never a good idea to touch an AM tower.