RF transmissivity measurements of a multilayered circular transparency to characterize attenuation behavior over a frequency range from 500 MHz to 18 GHz

Astronauts engaged in preparatory activities prior to Extravehicular Activity (EVA) may spend one or more hours inside the middeck airlock that has been partially evacuated to the vacuum of space. During this time, the astronauts may wish to review and update non-critical mission information and EVA particulars via a Radio Frequency Local Area Network (RF LAN) connection implemented on a laptop computer. In order to accomplish this, the RF transmission must pass through a multilayer 4-inch transparency, and then propagate to a downlink node located inside the Space Shuttle Orbiter (SSO) vehicle. This paper describes the processes used to verify the transmissivity (essentially the inverse of shielding effectiveness) of such a transparency. Two methods of measurement were employed. The results of each were correlated together after the fact, and showed good agreement.