The evolution of phased array antennas

Phased array antennas have evolved quite considerably over the last century or so, both in their design and uses. Dr. Randy Haupt began his lecture on the subject by explaining the many different uses for an array of antennas. Antennas are like “buckets for collecting electromagnetic waves.” A large antenna could suffice where arrays of antennas are used, but large antennas are generally hard to move. If one uses several smaller antennas, it is like using a large number of “little buckets,” which can be just as effective as the large antenna, but with greater mobility. In addition, phased arrays provide more control over the radiation pattern.

Haupt claims that the first example of array technology occurred in 1899 when S.G. Brown used two vertical antennas which were out of phase to create a rudimentary radar. The new scientific field began to grow over the next few years, and eventually, leading up to the Second World War, arrays were modified to have direction-finding systems, higher power capabilities, and the ability to steer the antenna. Arrays became much more widely used as they became tools for detecting incoming enemy planes. This led to a system of multiple early warning radars in Britain, which were used to detect bombers and other planes coming across the English Channel.

After the war, governments had a strong motivation to fund research and development of phased arrays. As a result, the field of phased array antennas exploded once again, leading to what is known as the Computer Age of phased arrays. In 1946, John Mauchly and J. Presper Eckert created the Electronic Numerical Integrator and Computer (ENIAC), which prompted researchers to integrate phased arrays with computers. The Computer Age of phased arrays lasted for nearly 20 years until 1964.

At the end of the Computer Age, the solid state array came into being and has remained popular and well-used through the present day. Innovations continued with the Molecular Electronic for Radar Applications (MERA) antenna, used primarily for military purposes, the advent of digital phase shifters, and the use of the tapered slot, which was very important in allowing antennas to receive and transmit broadband signals. In 1993, the work continued with the High Frequency Active Auroral Research Program (HAARP), a program dedicated to developing technology for radio communications and service which has been a popular target for conspiracy theorists since its inception. Another important innovation was the use of spherical arrays laid out on curved rather than flat surfaces.

Haupt anticipates a very bright future for phased arrays. As of now, arrays have to be added on to an existing structure, however, he anticipates that soon enough, the Integrated Sensor is Structure program will find a way to make it easy to integrate sensors into the structures of buildings, vehicles, or other objects, thus hiding the arrays and giving them a double use. He also anticipates the advent of digital beamforming, a high frequency surface wave radar which involves arrays floating on structures on the surface of the ocean, and the use of phased arrays in vehicles in space.