Guest Editorial.

This article focuses on the 2004 IEEE Microwave Theory and Techniques Society (IEEE MTT-S) International Microwave Symposium (IMS), which was held during 6-11 June 2004, in Fort Worth, Texas. 970 papers were originally submitted to the IEEE MTT-S IMS Technical Program Committee in December 2003 for possible presentation at the symposium in June 2004. Of those papers, 488 were accepted at the IEEE MTT-S IMS. Each of authors was then invited to expand their papers. 126 expanded papers were submitted and of these 65 papers have been accepted for publication. Of these, 22 were published in the November 2004 issue of the journal "IEEE Transactions on Microwave Theory and Techniques."