JED - June 2010 - (Page 38)

RF Interconnect By Barry Manz Solutions EW Systems Add More Fiber to Their Diet H 38 The Journal of Electronic Defense | June 2010 ere’s a chilling thought: If coaxial cables had not been able to achieve lower loss, greater shielding effectiveness and higher dissipation factors at increasingly higher frequencies, microwave and millimeterwave subsystems “as we know them” would be connected by waveguide. Instead of today’s rat’s nest of semi-rigid coax, threat warning systems, jammers and essentially every other type of high-frequency defense electronic system would be replete with conduits of “microwave plumbing.” Fortunately, coaxial cable, whether semi-rigid, hand-formable or flexible, has become the glue that binds together the subsystems that form the world’s defense subsystems. However, a competitor in the form of RF over fi ber (also known as Fiber over Glass or RFoG) is rapidly gaining momentum and is already replacing coax in some of its historically dominant domains. The key words in the last sentence are “some applications,” because while RFoG offers unchallenged advantages, they are principally achieved in applications that require long cable runs, for reasons that should become obvious later in this discussion. Before launching into how RFoG is making inroads into what has traditionally been a copper-dominated world, it helps to look at the problem of distributing highfrequency signals in general. For those who contemplate such things, all types of electrical wiring are a paradox. That is, without wiring, little or nothing electrical could be interconnected. However, they severely restrict what can be done, how well, and over what distances. Thus the feverish development of wireless technologies dedicated to “untethering” those remaining consumer products has not yet been unshackled by the ether via Bluetooth, Zigbee, WiFi and other standards. Hidden away from all this commercial excitement are the microwave and millimeter-wave EW, radar and communications subsystems that make up the bulk of defense electronic systems in ground, air and sea-based applications. Distributing RF and microwave signals in such systems requires well-matched coaxial transmission lines that must deal with stringent electromagnetic characteristics. These challenges are irrelevant at lower frequencies and thus have been ignored by digital designers until recently, as processor and bus speeds work their way up into the microwave region. Although largely unheralded, advances in coaxial cable technology have continuously been made over the years through efforts by companies such as W. L. Gore, Micro-Coax, Andrew, Times Microwave Systems, Radio Frequency Systems, M/A-COM, Huber & Suhner, and others. Loss, phase and amplitude stability, shielding effectiveness, and other important characteristics have been markedly improved thanks

Table of Contents for the Digital Edition of JED - June 2010

JED - June 2010
Table of Contents
The View From Here
From the President
The Monitor
Washington Report
World Report
Man-Portable COMINT
Technology Profile: RF Interconnect Solutions
EW 101
AOC Election Guide
Index of Advertisers
JED Sales Offices
JED Quick Look

JED - June 2010