As wireless transmission and reception gets complex, so does antenna design. Lately, several technologies have emerged to address the limitations of traditional antenna design, resulting in a variety of solutions with broader bandwidth and smarter capability. While some new approaches to antenna design are meeting the challenges of new-generation commercial applications, communications in defense is getting even more sophisticated, especially with the introduction of software-defined radio (SDR), modern electronic warfare (EW) systems and a host of other wideband transceiver technologies for mobile communications and surveillance. And the higher performance must come with miniature size.
Hence, another approach was required to meet these challenges. Fractal antenna technology has come to the rescue for designers in military and defense applications. Developed over the last 20 years, fractal antennas have proven to be a fundamentally important breakthrough in antenna technology. This technology has allowed for antennas that are more powerful, versatile and compact. Because a fractal antenna uses fractal geometry and builds a complex pattern from the repetition of a simple shape, the inherent qualities of fractals enable the production of high-performance antennas that are typically 50% to 75% smaller than traditional ones. Because antenna performance is attained through the geometry of the conductor, rather than with the accumulation of separate components or separate elements that inevitably increase complexity and potential points of failure, fractal antennas offer better reliability and lower cost than traditional antennas.
To keep readers informed of recent developments in fractal antennas, RF Design's Defense Electronics supplement has invited Nathan Cohen of Fractal Antenna Systems to educate our readers on this emerging antenna technology. In the article titled “Fractals' New Era in Military Antenna Design,” the author sheds new light on this technology and focuses on the benefits of using fractals in antenna design. Some of the benefits include broadband and multiband frequency response that derives from the inherent properties of the fractal geometry of the antenna. Fractal technology also results in a compact size compared to antennas of conventional designs, while maintaining good to excellent efficiencies and gains. They also feature mechanical simplicity and design to particular multifrequency characteristics containing specified stop bands as well as specific multiple pass bands.
Another article, “Switched Radar Scenario Generation with Femtosecond Jitter,” by Roger L. Jungerman and Parmijit Samra of Agilent Technologies Inc. discusses the behavior of synchronous and asynchronous trigger inputs in terms of the latency and repeatability of triggered waveform events, because jitter in the waveform triggering can lead to inaccuracies in simulation and testing of advanced radar systems. This is particularly an issue in the case of phased array applications, where multiple arbitrary waveform generator (AWG) units are synchronized together and must be triggered nearly simultaneously.
With the widespread proliferation of wireless systems, users often want greater security and, at the same time, more open, easier-to-use systems that are better protected against hackers and intruders. The data these systems transport include everything from critical, company-confidential data to life-protecting surveillance information. A systems intruder could cause significant damage.
In the final article, “Trends in Wireless Radio,” Jeff Allen of FreeWave Technologies investigates various spread-spectrum radios that provide reliable data communications in the most adverse environments. Plus, the author presents a novel spread-spectrum radio with built-in data encryption, network IDs, multiple hopping sequences, in addition to other tactics to prevent interference and detection, as well as unauthorized access to guarantee security. They are designed to offer long-range and superior performance in noisy environments.