Future Radars
As noted in recent months complex and exotic waveform radars have started to penetrate the commercial market place, but there are still limitations, not least in cost terms especially at the higher end of the radar frequency spectrum but ways ahead are being established.
Around 48 months ago electrical engineers at the University of San Diego developed what is being called the most complex silicon phased array chip in the World. This is the first 16-element phased array chip that can transmit in the 30~50 GHz band. The uniformity and low coupling between the elements, the low current consumption and the chip's small size - just 3.2mm x 2.6mm - are all unprecedented.
Active phased arrays have been around for more than half a century. The antennas contain groups of transmit / receive modules in which the relative phases of the signals that feed them are varied so that the effective radiation pattern of the array is reinforced in a particular direction and suppressed in undesired directions. Some phased arrays are huge and very expensive. That high cost along with some technology limitations has until now prevented their wider commercial application but that is starting to change.
The UCSD chip packs 16 channels. The input signal is divided on-chip into 16 different paths with equal amplitude and phase using an innovative design. The phase and gain of each channel is controlled electronically to direct the antenna beam to look in a specific direction. Whilst the UCSD Chip is only a transmitter, the developers are already working on a receiver, the object being to produce a system on a chip, and that should dramatically reduce costs. So watch this space.
Complexity in Modern Maritime Navigation Radars
In January I noted the latest generation of Kelvin Hughes radars and their increasing waveform complexity. In recent months I have been made aware of a number of commercial maritime radars that exhibit multi-level PRI stagger and I raised the question with a specialist at emforensics.com as to why this should be; his response was most interesting.
"There's a lot of benefit in stability for target extraction in clutter, but it opens up the radar to fratricidal interference from "like" radars, and the more radars there are (about 3 million in US waters), the harder it becomes to find a space in the spectrum that's not already being used by another copy of the same radar. So the complex wave-form has emerged as a way to create that space, by reducing the likelihood that radar 'A' will be in PRI phase with radar 'B'."
The presence of emitters with multiple levels of stagger must be causing identification problems for older ESM systems, unless the system is manned by an expert with considerable knowledge in this field.
4Apr12
