JED - April 2009 - (Page 43)

GaN Amplifiers: Boosting the Power behind Communications Jammers By John Knowles The Journal of Electronic Defense | April 2009 W hen remote-controlled improvised explosive devices (IEDs) began to appear in Iraq back in 2003 to 2004, it wasn’t just the US Army and US Marine Corps that were caught flatfooted. The US electronic warfare (EW) industry also was unprepared to meet this threat. Up until this time, jamming in the communications frequencies usually was performed by large, dedicated EW platforms, like the USMC’s Marine EW Support System (MEWSS) vehicle, the US Air Force’s EC-130H Compass Call aircraft or the US Navy’s EA-6B Prowler aircraft. There were some smaller mobile and stationary, “hand emplaced” jammers in use as well. Almost all of these devices, however, were designed to jam communications at distances typically measured in miles. US forces did not perceive a need for small, relatively low-power, wideband communications jammers that would, in effect, create a 30- to 150-ft. jamming “bubble” around a vehicle or soldier. This requirement evolved rapidly, however, once IEDs appeared in large numbers in Iraq, and soon afterward in Afghanistan. As urgent requirements for IED jammers began to emerge in 2004 and 2005, it created a wide open market for the US defense industry. No US company was manufacturing IED jammers before Operation Iraqi Freedom in 2003. Over the next five years, more than 40 companies (most of them from outside the traditional EW market) would offer IED jammer solutions. With the US Army and US Marine Corps buying thousands of IED jammers per year beginning around 2005, there has been a lot of emphasis on the developing supply chain that would turn out IED jammer components and subsystems quickly and efficiently. A critical component of any IED jammer is, of course, the power amplifier. Until the market for IED jammers emerged, there was a very limited demand for small, rugged and efficient broadband high-power amplifiers. For power amplifier manufacturers, however, this changed almost overnight. Fortunately, reliable amplifier technology was available. NEW TECHNOLOGY For IED jammer applications, many power amplifier manufacturers rely on Gallium Nitride (GaN) transistor technology. GaN devices offer significantly better performance compared with Gallium Arsenide (GaAs), laterally diffused metal oxide semiconductor (LDMOS) and vertical diffusion metal-oxide semicon- ductor (VDMOS) transistors. The advantages of GaN are described in this quote from Milmega (Isle of Wight, UK) in a September 2008 Microwave Journal article: “The inherent properties of GaN have a number of advantages to offer the amplifier designer. A major one is that the transistor structure enables the development of a product that allows operation into high VSWR loads, including short and open circuits, without the need for protective circuits or isolators. The higher gains of GaN transistors, compared to those of competing technologies, reduce both the overall transistor count and the number of combining stages required. Operation from high voltages results in a less complex power supply design, an important feature in determining the overall reliability of an amplifier structure.” Today, a number of amplifier manufacturers produce GaN devices for IED and general communications jamming applications. Aethercomm Inc. (Carlsbad, CA) makes a range of GaN power amplifiers that operate from +28Vdc and +50Vdc power supplies. Among its newest products are the SSPA 0.020-1.00030-28V and SSPA 0.020-1.000-30-48V. Both amplifiers cover the 20- to 1,000MHz range with a typical gain of 50 dB. The SSPA 0.020-1.000-30-28V offers an 43

Table of Contents for the Digital Edition of JED - April 2009

JED - April 2009
The View From Here
From the President
The Monitor
Washington Report
World Report
Lethal SEAD
Airborne SIGINT Forecast
RF Power Sources for IED Jammers
Roost Profile
EW 101
AOC News
JED Sales Offices
Index of Advertisers
JED Quick Look

JED - April 2009