Allen, We have used a biconilog for radiated emissions testing in our 3m semi-anechoic chamber for the past three years. We have done extensive correlation studies to the biconicals we own and found there to be little issue with using the biconilog. Its well balanced and therefore, we're not seeing an issue with coupling to the ground plane. You may recall in years past, when baluns weren't as well balanced as most are today, antenna manufacturers would tag the ground side of an antenna so you could point that side down in a vertical measurement. I've found that to be unnecessary with our biconilog. On the other hand, I'm merely an EMC engineer and not an antenna designer and therefore I can only share our experiences. That being said, I'll buy another biconilog if I build a second chamber.
Don Rhodes Principal EMC Engineer 503.685.8588 voice 503.685.7256 fax [email protected] -----Original Message----- From: Tudor, Allen [mailto:[email protected]] Sent: Wednesday, November 15, 2000 8:36 AM To: [email protected] Subject: Which Antenna? Greetings, I am having a fully anechoic pre-compliance test chamber built. By fully anechoic, I mean ferrite tiles will be installed on the floor as well as the walls and ceiling. The inner dimensions of the chamber will be 24 feet long by 14 feet wide by 13 feet high. The chamber will be used for radiated emissions as well as radiated immunity. Radiated emissions testing will be from 30MHz to 1GHz. I am looking at a biconilog antenna that can be used for emissions and immunity testing. However; for emissions measurements, the salesman recommends that I use separate biconical and log-periodic antennas. He says that if I use the biconilog antenna for emissions measurements, there will be some coupling to the ground plane when the antenna is in the vertical position. However, this chamber will have ferrite on the floor, so I don't know if that is a valid argument. Aside from the expense of two additional antennas, I have two conflicting concerns. 1. I would rather not have to work with more than one antenna if I don't have to due to down time and possible damage to an antenna. 2. On the flip side, I want to make sure that I have repeatable results, especially at the low end of the spectrum. Any advice would be greatly appreciated. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
