We see antennas everywhere. You likely have one or more on you right now, under the plastic cover of your cellphone or smartwatch. Cars now bristle with antennas …. AM/FM radio, GPS navigation, tire pressure monitoring …. And new driver support technology is being added regularly. Some homes still use TV antennas … and don’t forget those satellite dish antennas proliferating on rooftops.
Antennas provide a specific service – to insert information into the environment and extract it some distance away. Antennas provide the pure realization of Action at a Distance.
Many complex systems require the signals to be accurately pointed in a specific direction, even moving to follow a changing situation. Air traffic control, military combat, and space exploration put incredible requirements on their antennas. We all watch the news and ask “How do they do that?” This presentation is an attempt to provide some understanding.
The antennas used in such service are mind-bogglingly complicated, but we will break them down into digestible bite-size-chunks so we can learn their fascinating stories.
Part 1 described antenna arrays that precisely aim their signals though mechanical movement or switching between radiating elements. Part 2 discusses antenna arrays that remain mechanically stationary, while the signal directionality is precisely controlled by adding a specific phase shift to each radiating element.