Somewhere between basic electricity and solid-state electronics, student engineers are presented with the capacitor, the inductor, and then a full introduction to the complementary relationship between these two reactive components. Usually, the resistor is revisited, the concept of resistance is then distinguished from the concept of impedance, and the introduction of vectors soon follows to map out the steady-state behavior of circuits using all three of these circuit elements. While this stage of learning may be difficult, it also presents the first elegant example of the possibilities that can emerge with the combination of truly complementary capabilities.

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Among all the possible combinations in electronics, none is more elegant and practical than the circuit formed when a capacitor and inductor are connected in parallel. This LC circuit, or tank circuit, dynamically stores energy, shuffling it between the electric field of the capacitor and the magnetic field of the inductor in a precise, continuous, sinusoidal pattern. This property enables vital circuit functions, such as tuning or frequency synthesis. Connecting these two components together in other topologies enables a host of other capabilities, including filtering and efficient energy transfer in switching converters. All of these applications transcend the limitations of what is possible using only a single component.

Of course, the powerful nature of complementary relationships extends to defense electronics at the circuit, system and even platform level. For example, one of the first things Western defense analysts noticed about the Mig 29 Fulcrum when it was first seen outside the former Soviet Union in July 1986 was the peculiar glass blister forward and slightly right of the canopy. This houses a combined active laser rangefinder and infrared search-and-track (IRST) sensor. This system further complements the main radar, which can passively track a target by slaving to the combined IRST system, going active if the laser loses the target (as it might in cloud cover). Interestingly, the Fulcrum itself is complementary to the Su-27 Flanker, forming a “high-low” mix in response to that adapted by the U.S. with the complementary deployment of the F-15 and F-16, as well as the F-14 and F-18.

This issue of Defense Electronics is rich with examples of complementary functions and capabilities, and even echoes the complementary nature of electronics itself, which manipulates electricity for the tasks of carrying either energy or information. The features begin with an article by AVX that deals with capacitors for use in radar or other pulsed-power applications. The third and final article from Lodestone Pacific deals with high-Q inductors for RF signal processing that are extremely useful for SDR platforms. Both articles deal with the problem of enhancing a component's desired characteristics while reducing parasitic elements (such as ESL in capacitors, inter-winding capacitance in inductors, and series resistance in both). What both articles reveal is that addressing this challenge relies heavily on materials science and mechanical design, the perfect complements to electrical engineering.

Between these two articles, the second feature, contributed by Trace Systems, deals with the importance of establishing communications networks along the tactical edge of the battlefield. These networks complement the links between single nodes on the battlefield and centralized command stations. The article discusses mesh networks using a slew of complementary communications technologies that interconnect command centers, individual warfighters, and even remote wireless sensors.

Other companies in this issue include TVN Systems and Omega Sensors, which are developing PEM fuel-cell technology and MEMS inertial-sensor technology, respectively. Low cost is the focus of both efforts. If these technologies could be integrated with existing battery and GPS technology, it might enable a truly autonomous handheld tactical navigation device. The importance of having such complementary capabilities will increase with the increasing vulnerability — underscored by recent world events — of electrical grids and GPS satellite networks. On that note, it would certainly make for an interesting chapter in world history if two major military and economic superpowers could co-exist in a complementary, though admittedly complex, relationship as the world's premier first responders to global-scale natural disasters.