Interference and wireless PC cards
A few days ago, I observed that if I put my hand or any other object near the wireless card installed on our laptops running Windows XP, the signal strength becomes low and ultimately the connectivity is lost. To get connected, I needed to configure it once again, along with the WEP keys. Any idea what's going on?

    Requires Free Membership to View

    Login

    SearchMobileComputing.com members gain immediate and unlimited access to expert guides for mobile deployment, management and security, industry trends, and more-- all at no cost. Join me on SearchMobileComputing.com today!

    Kate Gerwig, Editorial Director

    By submitting your registration information to SearchMobileComputing.com you agree to receive email communications from TechTarget and TechTarget partners. We encourage you to read our Privacy Policy which contains important disclosures about how we collect and use your registration and other information. If you reside outside of the United States, by submitting this registration information you consent to having your personal data transferred to and processed in the United States. Your use of SearchMobileComputing.com is governed by our Terms of Use. You may contact us at webmaster@TechTarget.com.

As you have noticed, wireless PC cards have on-board antennas that are subject to interference from a wide variety of sources, including the body parts. It's not all that unusual for signal strength to drop when you put your hand or arm between the card and the AP. But connections are typically maintained if signal strength is reasonably strong to start; link speed simply drops as signal strength degrades.

Options for avoiding connection loss due to signal degradation include the following:

  • Check your card and AP configurations to ensure they are auto-adjusting data rates. If either device insists on 11 Mbps, then you'll lose the connection rather than fall back to 5.5 Mbps.
  • Use a wireless PC card with a stronger on-board antenna. I'm not kidding. PC cards do vary quite a bit, and you might obtain better results with another card.
  • Increase overall signal strength in the area where the laptop is located by adding more APs or moving the APs you already have. After all, your goal isn't to provide good signal to an empty room, but to provide acceptable signal levels during normal WLAN use.
  • Add an external antenna to get more mileage from existing transceivers. Some PC cards do accept external antennas, but you'll get more overall benefit by adding AP antennas. To learn more about external antennas, read this tip.
With regard to losing your manual WEP keys, you should be able to configure those keys persistently into Windows XP. Just use the Advanced button of the Available Wireless Networks panel to Add a network with manual keys. That configuration will then be applied every time the laptop attempts to connect to an AP with the specified network name (SSID).

This was first published in April 2004

Back to top