Exhibit 4.2 AGREEMENT TO FILE INSTRUMENTS WITH RESPECT TO LONG-TERM DEBT Pursuant to Regulations S-K Item 601(b)(4)(iii)(A), Electromagnetic Sciences, Inc. hereby agrees to cause to be filed with the Securities and Exchange Commission, upon its request, a copy of any instrument, not filed as an exhibit to the Report or Registration Statement to which this Exhibit pertains, with respect to long-term debt of Electromagnetic Sciences, Inc. or any consolidated subsidiary of Electromagnetic Sciences, Inc. ELECTROMAGNETIC SCIENCES, INC. Date: March 25, 1996 By: /s/ William S. Jacobs William S. Jacobs Vice President and General Counsel