Continued growth in telecommunications and video-hungry security markets has coaxial designers majoring on miniaturization.
BY STEVE SMITH
Over the past several months, engineers in the U.S., Europe and China have unveiled coaxial connectors that major in miniaturization and bandwidth capability, and that are compatible for a variety of board-mounting options in such growing markets as next-generation wireless communications.
In fact, according to a recent report by Gartner (www.gartner), new broadband wireless developments, including WiMAX, will keep spending on enterprise wireless LAN equipment in double digits over the next five years. And the overall Wi-Fi equipment market, according to Gartner, is expected to grow at a compound rate of 17.3% worldwide, reaching $3.1 billion by 2011.
For coax connector developer CommScope (www.commscope.com), the emergence of WiMAX (which is an equipment certification mark more than a technology) to support new bandwidth-intensive wireless services—especially video—has been good news. Recently, CommScope received approval for its products to be used by an unnamed major U.S. wireless carrier eyeing WiMAX. A leading manufacturer of HybridFiber Coaxial (HFC) solutions, CommScope, like other coax makers, is designing to meet unprecedented demand for video, voice, and data.
HFC connectivity solutions, from CommScope and others, are increasingly being used by telecom service providers, with fiber installed from the distribution center to nodes located near customers, and coax run from the nodes to individual homes or businesses. Using fiber as the backbone allows for more bandwidth than coax alone.
 Low-profile SMT-type connectors from JAE are designed for high-frequency transmission in wireless and broadcast applications. |
WiMAX is seen as a next-gen last-mile solution, providing a higher speed wireless alternative to cable and DSL. But frequency ranges that originally started at 960 MHz are now pushing 2.7 GHz, creating extreme challenges for typical larger diameter cables. As higher frequency demands continue to stretch the limits on traditional cable designs, CommScope says it continues to research and develop new ideas to support future WiMAX compatibility for its wireless products. “We are confident we can meet and exceed the emerging WiMAX frequency requirements using our proven broadband cable technology,” says senior vice president Larry Nelson, CTO for CommScope Wireless Engineering.
Miniaturization rules the day
Miniaturization coupled with the performance needed to meet wireless demands have also been the foundation for JAE’s (www.jae.com) recently introduced small SMT-type coaxial connector that conforms to the IEC60169-10 (SMB) standard for miniature coax connectors.
Targeting such designs as mobile phone base stations, WLAN access points, wireless equipment and amplifiers, and broadcasting and measuring equipment, JAE’s SMT-type connectors feature a low-profile height of 6.5 mm from the board, and an outer conductor SMT portion dowel designed to prevent connector misalignment under reflow. High frequency transmission of DC to 3 GHz is possible, says JAE, noting that a design concept based on high-accuracy simulation technology has been used to optimize impedance matching, low reflection, and low loss.
“Carrier companies accelerating the expansion of ubiquitous networking are adding and upgrading related base stations and access points, together with furthering performance levels, functions, and compactness,” says JAE in a product summary. “Now, even for the coaxial connectors that were conventionally thru-hole, the demands for more compact types compatible with automatic mounting and surface mounting are increasing.”
 Tyco Electronics’ MULTI-BEAM XL terminates directly into PCB-mounted receptacles. |
Also targeting telecommunications applications, Tyco Electronics (www.tycoelectronics.com) recently unveiled its MULTI-BEAM XL coax connector. Similar to the company’s pass-thru connector design, the coax version securely terminates directly into PCB-mounted receptacles, simultaneously connecting power, signal and coax.
The separation of power is designed to eliminate concerns of high voltage power running through circuit boards better suited to carry only low voltage. Tyco says its XL receptacle serves as a “docking” station for applications where high and low voltage on both cables and circuit boards need to be routed through one central location.
In November, RF interconnect developer Trompeter Electronics (www.tompeter.com) was issued a patent for its UPL250 mini-BNC connector that also targets the voice-data-video market, particularly telecommunications carriers looking for high performance in increasingly crowded spaces. Trompeter says its new mini-BNC is designed to provide a 40% gain in connector density, and offers a plug that is 60% smaller than a full-size BNC. According to the company, the UPL250 series delivers 75-ohm impedance throughout the entire frequency range and “outstanding return loss.”
 Patented mini-BNC connectors from Trompeter Electronics offer a plug that is 60% smaller than a full-size BNC. |
Trompeter notes that while the UPL250 was originally designed to address challenges specific to telecom central offices, it can also be used wherever standard BNCs are already in use, such as HDTV broadcast applications. “Both the broadcast and telco markets have recognized the value of our miniaturized product and are actively adopting it in cramped central offices and mobile production vans—places where density is an issue,” says Tom Barber, Trompeter director of sales.
Around the world in coax
Overseas, German connectivity manufacturer Harting KGaA (www.harting.com) is addressing high-speed data needs for industrial environments with its shielded E-Coax connector. With an impedance of 50 ohms, the connector’s crimp contact in the coaxial position is designed for use with large-diameter cables in coax-based data systems, such as the Eurobalise data transmission network used in the European Train Control System (ETCS).
The E-Coax is part of the company’s Quintax connector family, shielded devices that are used in such industrial bus systems as Profibus and Ethernet.
Meanwhile, ITC (www.itcplug), a California-based division of AudioQuest/The Quest Group, recently unveiled a series of coax connectors targeting European audio/video designs, providing an alternative to soldering or compression methods. ITC’s tool-less coax termination solution aims to reduce termination time, complexity, and failure rate. Connectors feature a captive center pin that grips onto the center conductor via a proprietary spring tension system. A toothed outer retaining ring holds the connector firmly in place while spinning inside the product to provide torsional strain relief.
 A shielded connector from Harting KGaA is built for industrial environments where large-diameter coax cables are required. |
“In Europe, the proliferation of satellite video and cable television has contributed to a very widespread use of what are variously known as ‘coax’ or ‘Euro antenna’ connectors, depending on the country,” explains William Low, CEO of The Quest Group. “ITC’s tool-less system reduces termination time, while the connectors’ high performance reduces failure rates. Both of these advantages add up to significant cost savings for European installers.”
The European coax line is available in F, BNC, and RCA connector configurations for 18-, 20-, and 24-AWG coax cable, with additional types expected to be introducted by the end of the year.
Miniaturization and high-frequency are also the trends in mainland China and Taiwan, where engineers are designing to meet growth in worldwide telecom and security markets. Xi’an Connector Technology’s (www.xianconnector.com) miniaturized DB4 series, for example, was modified from its D4 series of miniature connectors and features 50-ohm characteristic impedance and frequency of 0 to 20 GHz. Some Taiwanese manufacturers are reportedly looking to fiberoptic technology as part of future coaxial connector research and development, emphasizing high performance, and cost-effective and simplified installation for end users.
“Time and cost issues are major factors for installers wherever they are in the world,” sums The Quest Group’s Low.
STEVE SMITH is executive editor for Connector Specifier.
A coax sampler
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Recently introduced coaxial connector solutions include:
- V-Bite RF edgecard connectors from Bomar Interconnect Products (www.bomarinterconnect.com) now include a male Type N, and are designed for such high-power applications as base stations, cellular antennas, RF and microwave components, and test and measurement equipment. These small footprint connectors for high-density designs accommodate RG-8, 58, 41, and 225 coax cable, are engineered to snap in place onto the PCB before hand or reflow soldering. Parts are supported from below and above the board to disperse rotational torque relief, minimizing stress on the solder area.
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- Broadwave Technologies’ (www.broadwave.com) SMA female-to-FAKRA-SMB male adapter (Model 412491315) is designed to mate with FAKRA SMB female adapters in such automotive applications as satellite radio, GPS systems, and vehicular Internet access. Built for high interconnect yield due to less force required, the adapter features DC to 4 GHz, VSWR <1.2:1, and 00.5 dB maximum insertion loss.
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- Designed for audio/video equipment manufacturers who want to build their own cable assemblies, L-com Connectivity Products’ (www.l-com.com) RG-59/U and RG-6/U RCA push-on crimp connectors are built for 75-ohm coaxial cable.
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- Front- and rear-mount configurations with solder cup electrical terminations are now available on SMA bulkhead-mount coax connectors offered by RF Connectors/RF Industries (www.rfindustries.com). Connector bodies are machined brass with nickel gold plating. All dielectrics are PTFE with gold-plated contacts. Male and female SMA interfaces are available.
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- For board-to-board designs, QMS/QFS Q2 connectors from Samtec (www.samtec.com) feature one or two RF connectors per end, with up to 156 single-ended or 48 signal pairs per connector on a 0.635-mm pitch with an internal ground plane. These high-density, high-speed connectors can be combined with MMCX-scale or other RF connectors.
