Emerging applications for microwave and RF technology promise to keep researchers and manufacturers busy for several years. Many of the long-time markets for high-frequency electronics, such as commercial communications, military radar, and electronic-warfare (EW) systems, appear strong for the future. Yet the use of RF and microwave signals should extend well beyond those traditional markets in the years to come.

Investments in commercial communications and military electronics are projected to range from steady to strong over the next few years by several leading market research firms, including ABI Research (www.abiresearch.com). Global expansion of third-generation (3G) and fourth-generation (4G) mobile cellular services, including Long Term Evolution (LTE) systems, should continue to fuel opportunities. And in the wireless broadband arena, WiMAX represents a growing market for high-frequency electronics suppliers.

MILITARY MARKETS
Opportunities for traditional military markets, such as components for EW, radar, and signal-intelligence (SIGINT) systems, will continue to be strong under the new administration in the United States, which inherits an ongoing three-year commitment to operations in Iraq. Staple applications, such as the aircraft traffic alert and collision-avoidance system (TCAS)and its passive commercial aviation counterpart, the portable collision avoidance system (PCAS)require continued support, maintenance, and retrofits.

A promising area for suppliers in military-electronics markets is in high-power RF/microwave systems that have traditionally relied on vacuum-tube amplifiers, such as traveling- wave-tube amplifiers (TWTAs). Many program managers for these systems are looking for solid-state replacements with their higher reliability and longer operating lifetimes. The increasing power levels possible from gallium-arsenide (GaAs) field-effect transistors (FETs), silicon-LDMOS transistors, silicon-carbide (SiC) power transistors, and gallium-nitride (GaN) transistors makes them viable options for TWTAs in high-power radars and jammers when the outputs of multiple devices are summed by means of power combiners.

In addition to these traditional applications, the military's fascination with microwave power transmission (MPT) may provide an opportunity for solid-state devices in systems that were once dominated by high-power microwave tubes, such as klystrons, magnetrons, and TWTs. MPT technology, first demonstrated by Nikola Tesla as early as 1899 in experiments performed at Colorado Springs, CO, provides the potential for remotely powering electronic devices, such as sensors, or even transferring electrical energy to earth from solar collectors orbiting the planet. Initial work on MPT has been at 2.45 GHz because of available magnetrons. But the availability of higher power solid-state power devices may clear the way for the use of other frequencies.

Another more nontraditional RF/microwave military application is in the growing area of directed-energy weapons. For example, defense specialist SAIC (www.saic.com) in San Diego, CA recently received an indefinite-delivery/ indefinite-quantity (IDIQ) contract for $16 million to conduct research on the potential effects and lethality of highpower- microwave (HPM) weapons. The contract, which is managed by the US Air Force Research Laboratory (AFRL), is also aimed at developing HPM weapons and in learning more about the potential of psychotronic weapons. These electromagnetic (EM) weapons interact with a target's nervous system. This new generation of EM-based weapons is being touted as "non-lethal" weapons as part of a future "kinder, gentler" military force. It also has possible use in crowd control and Department of Homeland Security (DHS) applications.

In addition, the DHS is examining the use of laser and microwave pulse technologies to guard against terrorist shoulder-fired missile attacks on commercial aircraft. DHS is evaluating the microwave-pulsed Vigilant Eagle system developed by Raytheon (www.raytheon.com) to throw off a missile's guidance system. In addition, DHS is investing in a study of a modified Tactical High Energy Laser as used in the SkyGuard system from Northrop Grumman (www.northropgrumman.com) see Figure>.

COMMERCIAL GROWTH
In commercial and consumer markets, the automotive area offers many opportunities for RF and microwave technology. Infotainment continues to be a hot area with possibilities for wireless video streaming through ultrawideband (UWB) technology. In addition, an increasing amount of drivers are relying on navigation through either factory or after-market devices. Although these areas will continue to grow, a new opportunity has emerged in collision avoidance beyond the 77-GHz radarsensor- based systems in many high-end car models. These newer, sensor-based systems work on ultrasound technology. The sensor transmits and receives sound-wave signals both to and from the moving vehicle. Any colliding object that appears in the vehicle's way will be detected and a warning will be issued. At Japan's CEATEC this past October, engineers at Nissan Motor Co.'s Advanced Technology Center (www.nissan-global.com) unveiled their idea for the next generation of crash-avoidance systems. Based on joint research with the Research Center for Advanced Science and Technology at the University of Tokyo, Nissan has built the Biomimetic Car Robot Drive or BR23C. It recreates the characteristics of a bumblebee with the goal of producing a system that prevents collisions altogether.

A bee's compound eyes can see more than 300-deg. This allows a bumblebee to fly uninterrupted within its personal space. To recreate the function of a compound eye, engineers came up with the idea of a Laser Range Finder (LRF). The LRF detects obstacles to 2 m away within a 180-deg. radius in front of the BR23C. It then calculates the distance to them and sends a signal to an on-board microprocessor, which is instantly translated into collision avoidance. According to the researchers, the robot car's instincts are "intelligent." Once it detects an obstacle, the car robot will instantly turn its wheels at right angles or greater to avoid a collision.

Some less lofty and yet potentially huge application areas also can be found in the consumer space. The switchover to digital video broadcasting (DVB), for example, is creating a need for new transmitters and associated components, such as amplifiers and antennas. In addition, forecasts are sizeable for nearfield communications (NFC) for mobile payments. Many consumers pay with plastica credit or debit card. Soon, more people will be able to simply wave their credit cards or mobile devices in order to pay for a purchaseno card sliding, no keypad for a personal identification number (PIN), and no signature needed. Dubbed contactless payment, this capability has already been put through a number of trials.

Earlier this year, a select group of San Francisco Bay Area Rapid Transit District (BART) riders took part in a firstin- the-nation trial to pay for their fares and food, receive discounts, and check account balances using their mobile phones. That phone contained a contactless chip that enables transactions without a traditional plastic card. According to results from BART, First Data, and ViVOtech (www.vivotech.com), high use was demonstrated when both transit fare and retail payments were combined in the same phone. To pay at BART stations, trial participants tapped their NFC-equipped mobile phones, which were provided by Sprint, on top of the BART fare gates. This past year, radio-frequency-identification (RFID) leader KSW Microtec (www.ksw-microtec.de) also unveiled a contactless payment RFID sticker for mobile phones.

One of the most promising emerging market areas for RF and microwave companies is in medical applications. Widely touted patient-monitoring systems offer a way to systematically check blood pressure, pulse rate, and more and send that information to a base station, where it can then be accessed by a physician. A recent example of such a system hails from Gentag, Inc. (www.gentag.com). It allow the next generation of cell phones, personal digital assistants (PDAs), or wireless laptops to be used as readers for sensor applications like glucose testing with a cell phone. The technology combines emerging multiprotocol and multi-function cell-phone or WiFi technology with a passive, disposable radio-frequency-identification (RFID) sensor platform with external analog and digital ports. That hardware is combined with the company's Internet software, which allows real-time overlays of geolocation information, unique ID information, sensor data, pictures, and software. It therefore allows the real-time scanning of low-cost RFID 13.56-MHz sensors.

Last summer, Gentag, Inc. USA and MacroArray Technologies, LLC USA (www.macroarraytechnologies.com) entered into a development program to design a wireless immunoassay that incorporates Gentag's communication technology and MacroArray's urine diagnostic test for prostate cancer. Their goal is to simplify and expand low-cost wireless diagnostic assays for early cancer detection. Essentially, men will place a urine sample on the test strip that incorporates an embedded wireless sensor tag. The antibodies in the strip test will react with the antigens in the urine. The resulting data will be sensed by the embedded electronic tag and communicated to a cell phone or PDA, to transmit the results to the attending physician.

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To monitor internal functions in a non-invasive way, in-body networks also have been created. Camera-maker Olympus (www.olympusamerica.com), for example, garnered headlines last year for creating a wireless capsule endoscope that can non-invasively monitor the small intestine. In addition, Zarlink Semiconductor (www.zarlink.com) debuted the implantable ZL70101 transceiver. It simplifies in-body communications by connecting implanted medical devices and monitoring equipment. Zarlink also is part of a consortium that has successfully designed and clinically tested an in-body model microgenerator that converts energy from the heartbeat into power for implanted medical devices. Other partners in the Self-Energizing Implantable Medical Microsystem (SIMM) project (www.implantgen.com) include InVivo Technology Ltd. (www.invivotechnology.com), Perpetuum Ltd. (www.perpetuum.com), Finsbury Orthopaedics (www.finsbury.org), and Odstock Medical (www.odstockmedical.com).

The SIMM microgenerator could help to power implanted medical devices by augmenting the existing battery for devices like cardiac pacemakers and implanted cardioverter defibrillators (ICDs). This catheter-mounted device would be placed on a conventional pacemaker or defibrillator lead. The device harvests energy by using differential pressure within the chambers of the heart to drive a linear generator. During testing, the device generated one-third of the power required to run a pacemaker (excluding pacing demand). Next-generation microgenerator devices are expected to fully power both the pacemaker and pacing requirements.

Microwave radiation offers great potential for nondestructive medical imaging. Millimeter-wave frequencies from about 100 to 1000 GHz in particular can provide views beneath the surface of the skin without the ionizing effects of x-rays. Given the capability of generating signals at those frequencies with sufficient strength, the technology could be used to detect skin cancer or image dental flaws underneath tooth enamel. The technology could also aid DHS by detecting objects under clothing at airports.

Generating high-amplitude millimeterwave signals is a limitation, of course. Yet work performed by Assistant Professor Ehsan Afshari of Cornell University and Harish Bhat, Assistant Professor of Mathematics at the University of California- Merced shows great promise for developing ICs with higher millimeterwave power levels. Their approach, reported this past year in the technical journal Physical Review E, is based on achieving on-chip nonlinear constructive interference. It enables multiple generated waveforms to be summed on-chip to generate a higher-level output signal, using an on-chip lattice of inductors grounded through capacitors. To create this on a chip, the researchers propose a lattice of squares comprised of inductors that are the equivalent of tiny coils of wire with each intersection grounded through a capacitor. The approach, which is partially funded by the National Science Foundation (NSF), can be implemented on silicon CMOS ICs. The researchers claim that frequencies to about 1.16 THz are possible with the approach, which may one day make medical microwave imaging a practical reality