Antennas – Wireless Achilles Heel?

While attending the WirelessHART seminar a while back we had a discussion about potential vulnerabilities and challenges with Wireless devices in classified areas and surprisingly or upon further consideration maybe not so much of a surprise, one of the real challenges faced by manufacturers is how to make the antenna explosion proof. When you think about it, an antenna is really an extension of the circuit (a wire) outside the explosion proof enclosure and hence an electrical path across the explosion proof boundary.


No problem you say as the only energy source in my device is the battery and associated very low currents to power both transmitter and battery. However, what about when the device is connected to a power supply, or uses a “bullet” to transmit the information wirelessly as a complement to the wired analogue signal perhaps? Of course the explosion protection will need to extend both ways since the antenna is also likely to serve as the “lightning rod” in the event of this sort of electrical activity and ‘cooked electronics’ tend not to work too well.

I understand a couple companies at least believe they have this problem solved but have also heard rumors that upon further investigation this is not true since the testing is only good under certain conditions so as always be sure to read the fine print.

If you know of solutions or horror stories about antennas, especially as it relates to explosion proof please let us know in the comments below so all our readers will gain the benefit of your experience. Thanks - Ian

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  • <p> Ian - the 1520 wireless access points we use for 802.11 a/b/g have 4 antennas and can be POE, 24 VDC, or 115 VAC powered. The ones we buy are rated for Division 2. Not sure how they get that rating but our electrical code people are satisfied it meets the area classification. </p> <p> Perhaps when you modify an existing enclosure the result is less clear . . . not sure. </p>

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  • <p>Ian - I did an Emerson Process Experts post today, [[<a href="http://www.emersonprocessxperts.com/archives/2010/11/wireless_device.html%7CWireless">http://www.emersonprocessxperts.com/archives/2010/11/wireless_device.html|Wireless</a> Devices in Hazardous Locations]] to highlight ways WirelessHART devices can be installed in hazardous areas.</p> <p> Regards, Jim Cahill</p>

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