While originally created for military applications, phase-array radar systems have become important in a variety of applications including automotive driver assist systems, satellite communications, advanced radar and more.
The heart of the phased-array radar system is the phased-array antenna which is composed of many radiating elements each with a phase shifter module that routes the microwave signal that is supplied to each radiating element through cables of varying length. The cables delay the wave, thereby shifting the relative phase of the output. A central computer calculates the proper phase delay for each of the radiating elements and switches in the appropriate combination of phase-shifters pathways.
Beams are formed by shifting the phase of the signal emitted from each radiating element, to provide constructive/destructive interference in order to steer the beams in the desired direction.
The use of phased-array antennas has enhanced the flexibility and effectiveness of radar. In particular, phased-array technology allows the radar beam to be controlled and adapted almost instantaneously. This flexibility enables the radar to carry out multiple functions simultaneously, such as surveillance, tracking and fire control, where each function carries out a number of looks.
This execution of multiple functions necessitates the study of radar resource management (RRM), which considers the prioritization and scheduling of radar looks, as well as task parameter selection and optimization.
RRM is especially important in overload situations, when the radar does not have sufficient time to schedule all requested looks. In this case, the radar scheduler must decide which looks should be scheduled and which should be delayed or dropped.
The benefits of arraying many antennas are many, including:
- More power
- Narrower beam shaping
- Beams can be steered without re-positioning individual antennas
- Greater reliability due to the antenna cluster effect
- Multiple beams are possible due to the control provided by phase shifters
- Less weight than gimbaled, single antennas for airborne purposes
Mathematically, a phased array is an example of N-slit diffraction, in which the radiation field at the receiving point is the result of the coherent addition of N point sources in a line. Since each individual antenna acts as a slit, emitting radio waves, their diffraction pattern can be calculated by adding the phase shift φ to the fringing term.
Want to learn more? Tonex offers Phased-Array Radar Systems Engineering Bootcamp, a 3-day course that covering phased array radar principles, latest technological developments, software, system analysis, requirements, architecture, design and operation.
For more information, questions, comments, contact us.