Conformity Magazine - December 2008 - (Page 44)

Antenna pattern improvement is a universal application for microwave absorbers. Conductive objects in the near field of an antenna can greatly alter its free space propagation characteristics. The net effect of this is a wider beam with increased side lobes. This condition can rescue system discrimination and increase the possibility of side-lobe jamming. Adding an absorbing material to the conductive areas will effectively match out radiation propagated in these directions and return the system to its designated free-space characteristics. A variety of antennas use absorber material for this problem and coat feeds struts and mounts that act as reflectors. Commercial There is a growing use of absorbers for reducing interference in commercial electronics. High-frequency wireless devices often have powerful transmitters and sensitive receivers in close proximity inside a cavity or housing. Spurious signals can cause leakage or system interference that degrades performance. Magnetic absorbers inside the cavity can reduce the “Q” of the cavity and absorb unwanted reflections. Custom shapes are die-cut from sheet material with pressure-sensitive adhesives (PSA) for application inside the noisy cavity. As devices such as computers and cell phones move to higher frequencies and speeds, the need for absorbers or absorbing shields increase. Application Examples—Commercial Consumer Radar Detectors The material in this application can be used inside microwave housings like back-up or crash-avoidance devices in the automotive sector. In antenna patterning, the goal is to minimize internal reflection so the receiving signal is less “noisy.” It reduces cross-talk between board-level antennas. Satellite Communications On an antenna feed line, the waveguide is used to “tune” each of the cavities and enhance antenna performance. It is also used to line the lid to reduce the “Q” of the RF component cavity. This application for single-band absorbers reduces RCS and can be used for maximum normal incidence attenuation at a discrete frequency. They are commonly used to minimize antenna reflections off structures such as ships and large vessels or for antenna pattern shaping. Network Switches Broadband foam is commonly used around antennas to provide isolation or side-lobe reduction. It can be die-cut into components for EMI reduction inside microwave cavities or used to manufacture antenna hats and text boxes. By adding foam to the perforated sheet metal door, customers are able to improve EMI emissions margins. Due to the open celled nature of foam, the customer is still able to blow air through the perforated sheet metal door. It can also be encapsulated into a textile cover for outdoor use. Conformity DeCember 2008 Automotive Back-Up/Crash Avoidance The material in this application is used inside microwave housings such as back-up or crash avoidance devices in the automotive sector. It reduces internal resonance, lowers the “Q” of the microwave cavity, and is also effective in isolating antennas from ground plane reflections. Application Examples—Military Surface Ships This application for single-band absorbers reduces RCS and can be used for maximum normal incidence attenuation at a discrete frequency. Commonly used to minimize antenna reflections from a ship, large vessel or for antenna pattern shaping, this type of material is used widely in military applications where radar equipment is relevant. Fighter Jets This unique application requires lightweight materials plus high-performing composites. For this application, weight savings is imperative. The application requires a conductive carbon-coated “lossy” material used to reduce the interfering reflections in airborne sea applications or any antenna or signal environment that requires the suppression of random reflections at specified frequencies. As global technology for electronics continues to evolve, microwave absorbing materials in both commercial and military applications will be required to perform at increasing levels. Faster clock speeds in electronics devices, more sophisticated military weaponry, and radar equipment is at the forefront of this changing industry. In 1950, the average American only thought about radar and high-tech devices when discussing military topics. Today, most Americans drive automobiles that contain at least one, if not two, devices that utilize radar technology. Whether a back-up device, cruise control, crash avoidance system or a regular radar detector, the use and need for these microwave absorbing materials will continue and the technology that surrounds radar, wireless devices, and high-speed electronics will need to continue to develop and evolve. For the world to be ready for this technology and the next wave of EMI and microwave absorbing materials, industry leaders need to be prepared and in tune with the next wave of technical changes. If the next 20 years are as exciting as the past 20, we’re in for an exciting ride! Scott Stephan is global product director for microwave products at Laird Technologies, Inc., and can be reached at scott.stephan@lairdtech.com. FAST Link www.conformity.com/2470 http://www.conformity.com/2470

Table of Contents Feed for the Digital Edition of Conformity Magazine - December 2008

Conformity Magazine - December 2008 Contents Editor's Note FCC Warns Regulatory Fee Payers About Potential "Phishing" Commission Prowls the Web to Enforce Its Regulations First DTV Rollout Initiated in Wilmington, NC New Standards List Released for the EU's Directive on the Safety of Toys ESD Association Call for Papers ESDA. JEDEC Announce Standards Development Cooperation Commission Releases Data on Local Telephone Competition The Future of ESD Testing ESD Open Forum Emerging Issues in Standards: China RoHS: One Year and Counting Challenges in Testing: Revisiting 10-Meter and 3-Meter Radiated Emission Measurements Design Fundamentals: Meeting the Shielding Challenges of Injection-Molded Plastics Focus On...Microwave Absorbers Buyer's Guide FDA Recalls Automated External Defibrillators FDA Revises Guidance on Medical Device Tracking Guidance Document Safety of Passive Implants Released FDA Offers Guidance on Marketing Diagnostic Ultrasound Systems EU Commission Issues Correction on Machinery Directive Standards Other CPSC Actions in the News Product Reviews IEC Standards Update UL Standards Update Looking Back: Items from Past Issues of Conformity Advertisers

Conformity Magazine - December 2008

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