Hi James, Although EN 300 220-2 (the radio standard for this product) does not specify receiver performance tests other than Rx blocking, EN 300 113 v.2.2.1 (for narrow band radios) has a test case as "Receiver spurious response rejection" to evaluate RF performance at the antenna port. A similar evaluation can be performed to the ZigBee, adjusting the unwanted signal level of -40 dBm to check the SAW filter performance.
Best regards, Deniz Demirci Senior Wireless / EMC Engineer National Technical Systems - Silicon Valley 41039 Boyce Road, Fremont, CA, 94538 Email: deniz.demi...@nts.com<mailto:deniz.demi...@nts.com> Main:510-578-3500 Fax:510-440-9525 From: James Pawson (U3C) [mailto:ja...@unit3compliance.co.uk] Sent: Tuesday, November 27, 2018 6:03 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Radiated RF Immunity vs. Radio Module Hello, I have a puzzling query today. I'm testing a product with an integrated radio module for 868MHz Zigbee. The EUT has an internal antenna connected to the UFL connector of the module. This means the wanted signal is provided by an antenna inside the test environment. The standard specifies a +40dB "link budget". My experience with testing radio modules has been that they are generally fairly robust to radiated interference outside of their tuned frequency. However this module is very much the opposite. When illuminated with 3V/m over most of the 80MHz to 1GHz band communication stops and the RSSI drops. If I bypass the EUT internal antenna and connect a coaxial cable directly to the UFL connector of the EUT RF module from the test generator (attenuated for +40dB link budget) then the product sails through testing at 10V/m! My initial thought was that the input of the module did not have sufficient filtering, resulting in AGC overload. However I've just de-soldered the can and there's a SAW filter in line with the RF path (input > SPDT switch > SAW > LNA > radio IC). So I'm not sure it's that any more. I can't see this being an module enclosure / system immunity problem because it passes the test at 10V/m when connected direct via coaxial cable (no antennae). Has anyone come across this sort of performance before? Avenues of investigation 1. Put an extra SAW filter in series with the antenna input before the RF module 2. Inject an out of band RF signal into the module and see where it ends up 3. Broken module, swap for a new one 4. Other? >From an approvals perspective, the module as supplied will meet the >requirements of 301 489-1 because the manufacturer will have tested it with a >coaxial input feed. However when tested with an antennae attached it doesn't >work under these immunity conditions. It feels like the standard doesn't cover >this scenario adequately. Frustrating. I'm contacting the manufacturer in parallel. Thanks in advance for any assistance James (also cross posted to a different forum) - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
