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Japan Aerospace Exploration Agency

D-SEND project / Silent supersonic transport technology


August 31, 2009

An antenna pattern test conducted for the silent supersonic technology demonstrator

JAXA has planned a flight test to demonstrate a technology to reduce the sonic boom (acoustic noise caused by a shock wave) generated by the supersonic transport. We are now proceeding with the design of "the silent supersonic technology demonstrator," an unmanned aircraft to be used for the demonstration testing.
From May through July, 2009, our team carried out an antenna pattern test for the silent supersonic technology demonstrator at the Utsunomiya Plant of Fuji Heavy Industries, Ltd. The purpose of this test is to obtain data to determine the optimal number of antennas and the optimal antenna layout for establishing radio wave communications between the demonstrator and ground.
We transmitted radio waves to a model scaled at about one quarter of the size of the actual aircraft to measure the strength of the radio waves received by the antenna built into the model. The brown color of the model is from the conductive coating on the surface. The walls of the testing room are covered with a wave absorber to equalize the conditions of the surrounding radio waves and the radio waves in the air.
By repeatedly measuring the strength of the radio waves with rotation of the attitude of the model, we prepared what we call an "antenna pattern," a distribution chart showing the strength of the radio waves in the arrival direction. We are using this antenna pattern to design the demonstrator.