Hi. I recently bought a copy of IPC-D-317A. Page 24 in section 5.5.5.1 shows equation 5.42a) for differential stripline impedance Zo with the exponent "-.6B". Could I have a definition of "B"? Is it a ratio of two physical parameters? Section 5.5.4.1 (also on page 24) has "B" defined as "Height above reference plane", but it also has "H" defined exactly the same way. So I don't know what to make of "B". Also, which reference in the Bibliography on page 69 applies to this issue? I would like to acquire it and read it. Thank you very much for your help. Larry Martin Compaq Computer Corp. Colorado Springs, CO 719/548-6877 ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################