A Massachusetts-based company has developed two lightning protection devices specifically for wireless networks that can be retrofitted into existing systems.
M/A-Com Inc. of Lowell, Mass., develops and manufactures radio integrated circuits, passive and control devices, antennas, cables and interconnects. The company has manufacturing facilities worldwide and sells products to some of the world’s largest infrastructure manufacturers, such as Motorola Inc., L.M. Ericsson, Northern Telecom Ltd. and Nokia Corp.
M/A-Com hopes to spark the interest of engineers with those companies to consider the ability of M/A-Com to build the lightning protection devices into current products. “Because we’re an interconnection manufacturer, we have a lower cost solution because we can build the product as an entire unit,” said Dean Gammell, European marketing manager for M/A-Com’s interconnection business unit. “We build the connectors, and build it into the connectors,” he said.
The company is offering a surge protector for broadband systems and quarter wave stub tuners for narrowband systems. Both protect the system from electromagnetic pulse, and operate on Global System for Mobile communications, Personal Communications Systems 1900 and Digital Cellular Systems 1800 networks.
M/A-Com said it has been manufacturing the devices for certain customers for the last two years, but now has a full product range to launch commercially.
The surge protector uses gas discharge tube technology. The tube is hermetically sealed, containing an inert gas. It is inserted in the side of the device through an accessible weather-sealed port. During normal operation, the tube is inactive. When an installation is struck by lightning, a high voltage impulse will appear on the coaxial line, M/A-Com said.
When the impulse amplitude rises to a certain level, the impulse surpasses the dynamic voltage threshold of the tube and the electrodes discharge the energy to the ground. Configurations include straight and bulkhead-mounted adapters, which are more easily assimilated into existing systems, the company said. The typical shelf life of a replacement gas tube is five years. It is available for systems up to 2.5 GHz.
“Some manufacturers have put the lightning protection inside a base station circuit board, but the problem with that is you have already let it [lightning strike] into the electrical box,” Gammell said.
The M/A-Com device is inserted into the coaxial line between the ground unit and the antenna.
The quarter wave stub tuners tackle sparkover voltage and residual voltage. There are three port coaxial connectors. The third port extending from the mail through path is terminated in a short circuit at a pre-determined distance, one quarter wavelength at the desired center frequency. This design eliminates concerns about residual pulse, sparkover voltage and residual voltage. Stub tunes will absorb lightning strikes without the need to replace components.
“Motorola is expected to spend $3 million to $5 million a year on lightning protection, with ongoing GSM systems, new DCS systems and Asia-Pacific,” Gammell said.
