The new power of Patriot

In a hangar-like workshop not far from Boston, engineer Kevin O’Donnell slid a shining golden block into the towering face of a revolutionary new kind of radar.

The wall of plated aluminum squares was the first full-sized version of a futuristic radar Raytheon is developing for the legendary Patriot Air and Missile Defense System. Developed in record time using a powerful technology called gallium nitride (GaN), the new radar costs less to build, own and operate, and will give defenders an unblinking, 360-degree view.

The Raytheon-funded technology may become the latest upgrade in a system that has protected nations for decades. It is intended to replace the familiar circular ‘honeycomb’ face of the Patriot’s radar for one that is smooth and square, with two additional smaller arrays that stare backward.

Instead of one massive transmitter, Raytheon’s new radar uses individual transmit-receive modules that slide into the array like stacking children’s blocks. Think of the legacy honeycomb as a powerful flashlight shining through many lenses. This new, active electronically scanned radar array, or AESA, is more like many powerful flashlights operating together.

“You can lose some of the transmitters and it still works,” said Norm Cantin, Raytheon’s director of Patriot AESA programs.

Raytheon spent 15 years and more than $150 million to develop GaN, a unique technology that gives radio frequency amplifiers five times the power of traditional semiconductors. GaN circuits have been incorporated into a number of Raytheon products, including jammer circuits and other types of radar.

Earlier this year, the publication Aviation Week named Raytheon a 2015 Laureate winner for its GaN breakthrough. And industry news web site Breaking Defense wrote that Raytheon’s GaN technology is “the biggest thing since silicon.”

“This is the best of both worlds,” said AESA chief engineer Landon Rowland. “It’s an affordable upgrade path that enables new performance and dramatically improves the reliability of the system. The neat thing is, we’re not touching the stuff that’s been proven to work.”

This rendering shows a GaN-based Patriot radar with 360-degree capability.

Building a full-size, GaN-based radar is an important milestone toward a Patriot system that offers warfighters 360-degrees of coverage. Along with the upgraded main array, Raytheon’s Patriot solution will have two smaller arrays facing the rear to give the system full vision from horizon to horizon, front and back. That delivers continuous scanning in all directions. That’s a real advantage over other radars that spin to scan the horizon, but must stop to fix on a target and are blind in the back when they do.

“If we didn’t have GaN, we couldn’t build this,” said Cantin. “It would have to be much larger. GaN technology gives you more power density.”

Yet the GaN solution Raytheon plans to offer the Army is only the latest improvement in the constant evolution of Patriot, according to Cantin. “The beauty of Patriot, from serial number one on, is every new capability is upgradable, so you don’t throw away investments you’ve made over the years,” he said. “You upgrade.”

Mechanical engineer Kenneth Walsh Jr. inserts a GaN-based transmit-receive unit into the main radar array.

And GaN radar will be simpler to manufacture than legacy systems. “Much fewer parts,” Cantin said.

More powerful, more robust and easier to make, GaN radar could also be a ready improvement for standing Patriot systems. “It’s a little bit of a plug and play. We take the old antenna off and put the new AESA on,” Rowland said. “You get all the benefit without having a whole new radar development program.”