Something Suspicious Is in the Air By Courtland Milloy Monday, March 24, 2003; Page B01 The sign above the highway leading into the nation's capital advised motorists to "Report Suspicious Activity" and gave an 800 number for the Office of Homeland Security. As a reporter, I figured this was right up my alley and set out yesterday to report on things that struck me as suspicious. For instance, near the Jefferson Memorial, I saw a five-foot-tall metal box that was hooked up to an electrical outlet and equipped with a high-tech antenna and chrome-dome receptor. What was it? I asked...