The conventional methods of improving wireless system coverage performance are to increase the transmitter power and/or antenna gain. The high transmit power could lead to more power consumption and RF exposure issues. The use of a high-gain antenna could lead to a larger antenna size and increased weight and volume. An alternative approach would be to capture the available signal power more efficiently without increasing the transmitter power and/or increasing antenna size.

An important advantage of a wireless system for space applications in zero gravity is the flexibility; astronauts carrying portable computers are not tied to a particular wiring outlet. Wiring a space vehicle with a traditional local area network (LAN) can be very expensive and a large spacecraft may consist of multiple connected modules. Non-line- of-sight (NLOS) regions may exist in the bended tunnel environment.

Computer simulations were performed for 2.4-GHz WLAN signals propagating inside a bended tunnel environment that exists in spacecraft with multiple connected modules. The computer-simulated results indicated that the RF signals could be weak in the NLOS shadow regions due to much weaker diffracted fields and lack of the direct signals. A method to increase the received signal levels is proposed by appropriate transmitter and receiver antenna polarization alignment.

The simulations indicate that the proposed method could significantly improve the signal strength up to an order of magnitude in a bended tunnel environment.

This work was done by James Keiser and Catherine Sham of Johnson Space Center, Shian-uei Hwu of Barrios Technology, and Buveneka Desilva of Aerodyne Industries. MSC-25671-1

NASA Tech Briefs Magazine

This article first appeared in the May, 2015 issue of NASA Tech Briefs Magazine.

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