IEEC - Xircom CreditCard Netwave Adapter

Xircom CreditCard Netwave Adapter

Introduction

Local Area Networks (LANs) connect computers and peripheral devices such as printers and modems to allow the exchange of information (e.g., files and email) and the sharing of resources (e.g., printers). The connection is made via a cable -- twisted pair wire, coax, or optical fiber -- and data is exchanged at typically 10 Mbps using the Ethernet protocol. (For an in-depth discussion of communications technologies, see the previous bulletin "Global Voice, Video and Data")

Currently, over 60 million computers are connected in local area networks, and close to 10 million additional LAN ports are shipped annually. In comparison, shipments of wireless LAN adapters are puny at about 330,000 units in 1995.

Wireless LANs free the user from the constraints of the cable, replacing it by either an infrared (IR) or a radio frequency (RF) wireless connection. The freedom from the cable is interesting for mobile executives, but the real demand has been from applications such as:

roaming workers in warehouses

check-in personnel at rental car lots

doctors in hospitals

temporary sites such as conventions

With a wireless LAN adapter, users can create ad hoc peer-to-peer networks among themselves. Typically, however, wireless LAN adapters are used by selected individuals to feed into an existing wired LAN through a hub or access point.

Price is one reason -- although not the most one -- that most consumers continue to favor the wired LAN alternative. A Xircom Netwave PCMCIA wireless LAN adapter retails for about $300, almost three times more than the wired version. A base station (not required by a wired LAN) costs about $1100. Prices have been decreasing rapidly, but wireless LANs will continue to carry a price premium.

As was mentioned earlier, the wireless connection may utilize either infrared or radio frequency technology. The Xircom Netwave adapter relies on RF frequency-hopping, spread-spectrum technology at 2.4 GHZ (other systems may use 900 MHz but the trend is towards 2.4 GHz). The radio waves can penetrate walls, and the coverage area of a single base station is typically 500 feet in an office environment (accounting for walls and other interference). Multiple base stations can overlap to allow a mobile user to roam over an extended area without loosing connection. Throughput rates typically reach 2 Mbps maximum, but due to a smaller antenna the Xircom's range (150 ft) and data rate (1 Mbps) are lower. Wireless LANs typically use RF systems, and shipments are expected to increase to 1.8 million units in the year 2000.

The appeal of the Xircom CreditCard Netwave Adapter is that its antenna is fully integrated in an extended PCMCIA card, thus eliminating the need for an external module. Integrating the antenna meant sacrificing data rate and range, but in many cases the convenience of a small package will more than make up for that. A number of other vendors have or are about to introduce PCMCIA wireless LAN adapters with integrated antennas.

Construction

The construction of the Xircom wireless LAN adapter is discussed here in abbreviated form. For a detailed overview of communications, wireless LAN, and the use of low loss materials in high frequency applications, please contact Prismark Partners or the IEEC.

The Xircom Netwave adapter is of the standard PCMCIA type II format, i.e. 54 mm x 85.6 mm x 5 mm, except for the protruding antenna at the end opposite of the PCMCIA connector. The entire card weighs 31.1 grams, more than half of which is contributed by the housing, and the remainder by the actual electronics (board and components).

Two metal covers on the top and bottom of the card are attached to a plastic frame which is heavily plated to ground the entire assembly.

A single multilayer printed circuit board of a very thin construction and very fine geometries supports all the components. Devices are mounted on both sides, and are mostly in thin packages to meet the PCMCIA type II thickness requirements. The board was manufactured by Continental Circuits; the card itself was assembled in Singapore.

The appeal of the Xircom Netwave adapter lies in its integrated antenna. Typically, the antenna of an RF wireless LAN adapter is a simple dipole wire antenna that is connected to the PCMCIA card via a cable. The Xircom Netwave adapter, on the other hand uses a microstrip quarter-wave antenna, which is manufactured as part of the printed circuit board itself.

Integrated Antenna

A microstrip antenna was also used as a transmitting antenna in Motorola's two-way Tango pager. Rather than using a special low loss material (Rogers' TMM-3 in the Tango), the Xircom uses regular FR4. Low loss materials are of increasing importance in h gh frequency applications. Prismark will feature this area in an upcoming bulletin.

Copyright 1996 Integrated Electronics Engineering Center and Prismark Partners LLC.

9/96

Warranty Disclaimer -- All information used in the preparation of this report was obtained from sources believed to be reliable at the time the information was collected. Prismark Partners LLC, its employees, its agents, and assignees have exercised their best efforts in preparing this report. Prismark Partners LLC extends no warranties with respect to this information and shall bear no liability whatsoever to the report recipient or to any other party as a result of the use of this report or the information contained herein.

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