Electronic Military & Defense Annual Resource

4th Edition

Electronic Military & Defense magazine was developed for engineers, program managers, project managers, and those involved in the design and development of electronic and electro-optic systems for military, defense, and aerospace applications.

Issue link: https://electronicsmilitarydefense.epubxp.com/i/350588

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Page 32 of 59

Feature Electronic Military & Defense Annual Resource, 4th Edition 33 field is quasinull will not significantly modify the field distri- bution, and the object will not receive or absorb significant radiation. Such an objective was obtained by associating several basic antennas with specific amplitude and phase feeding, just as in array antennas. There are important differences, however, in that there is no periodic structure, and the group of antennas can be het- erogeneous and not necessarily locat- ed in the same plane. Moreover, the antennas are placed in such a way that they can be integrated or printed on the clothing. As a consequence, the anten- nas are close to the body and therefore are bent around the natural shape of the body. As an example of this principle, Figure 1 shows a group of three similar antennas located and fed in such a way that the convex region defined by the antennas receives signif- icantly low-level radiation. If a human body is placed in that convex region, it is expected that the radiated field will not be significantly affected. Therefore, the SAR will be low. To prove this behavior, we performed a simulation of two groups of antennas, each com- posed of three single radiating dipoles placed on the human body, as depicted in Figure 2. You can see that the elec- tromagnetic field is quite low, and that the body compliance with SAR level (here, 2W/kg) is achieved. For a total injected power value of 1 W, the calcu- lated SAR is 0.62 W/kg. Example Of WBAN Antenna Integration The Giante WBAN device is essentially a 3D one, but it is advantageously real- ized as a planar circuit. The 3D behav- ior stands because antennas must be f o l d e d on a part of the h u m a n b o d y like the arms, as shown in Figure 3. In prac- tice, the design of the antenna group will depend on operating fre- quency, the excitation circuit that needs to separately feed the three antennas of the group, the type of antennas, and the human body parameters. Usually, monopole antennas allow for obtaining a very satisfactory radiation pattern — provided that their relative orientation with respect to each other is optimized. Reliability isn't an option – it's a requirement. T W T A M P L I F I E R S | M I C R O W A V E P O W E R M O D U L E S | P O W E R S U P P L I E S dB Control delivers. Our high-power solutions for radar, ECM and EW threat simulation systems save lives every day. Easy to maintain, J\Z[VTJVUÄN\YLKHUKTVK\SHYS` designed, our TWTAs, MPMs and power supplies are so reliable that we're sole source on mission-critical ground-based, shipborne and high-altitude military manned and unmanned aircraft platforms with the U.S. Army, Navy, Air Force and major defense contractors worldwide. If your expectations are as high as your power requirements, contact us today. © 2014 dB Control Corp. All rights reserved. Photos provided courtesy U.S. Air Force, U.S. Army and U.S. Navy. +1 (510) 656-2325 marketing@dBControl.com www.dBControl.com Figure 3: An example of a military vest equipped with the Giante WBAN concept

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