Lunar Radar

In 1946, a Hungarian physicist and director of the research laboratory of the United Incandescent Lamps and Electric Company (Tungsram), Zoltan Bay, succeeded in bouncing radar waves off the Moon. Other experimenters had preceded DeWitt and Bay, but they had failed to detect lunar radar echoes.

Zoltán Bay and coworkers used a modified reconnaissance radar at 120 MHz, and succeeded in detecting radar echoes from the moon. Without a crystal controlled system, a wide bandwidth was used in the receiver before detection, and reduction of bandwidth was performed after detection.

The experiments were repeated many times, and all the feeble echo amplitudes were summed above the statistical sum of the noise amplitudes. About a thousand pulses had to be integrated over a period of 50 minutes. Integration was performed by a bank of switched voltmeters.

This method would later prove useful in radio astronomy.

Source: NASA