sergeyII March 11, 2014 at 14:18

Microwave passive radar in the 10 GHz band

Description

A mobile device has been made from equipment for receiving satellite TV channels and an electric motor, scanning from the horizon radiation in the range of 10 GHz. The data is visualized, an article with video pictures.

Technical implementation

Cheap components were used: a parabolic antenna with a converter for receiving data from television satellites, an electric motor, an infrared pair of LEDs and a photocell, brushes for transmitting power to the rotating part, and a pair of controllers. A stable mount is welded from steel pipes, an electric motor and an axis around which the plate rotates are fixed on it. There is a controller on the mount, which receives data from the rotating part and transfers it to the com port of the computer on which the data visualization program is running. There are only two data streams: receiver rotation information and measurement. The width of the lobe of the directional intake of a small parabolic dish is commensurate with a magnitude of 1 degree. For one revolution (approximately 1-1.5 seconds), approximately 400 12-bit measurements are necessary. Due to the relatively low signal-to-noise ratio for display on the screen, data is accumulated and averaged over several revolutions. To digitize the analog signal from the filter of the satellite head (converter), the RF logarithmic detector / controller AD8313 and ADC MAX1236 are used. For our amateur purposes, you can use a converter with any polarization and frequency suitable for the diameter of the antenna.

The experiments

It was found that from the walls of houses there is radiation above the background. If the locator is installed inside the room, then the glass windows are fixed by lowering the signal. Also, in a rustic brick house, we saw strange sources of 10 GHz radiation in the walls, and in the place where the mirror hangs, the signal level is lowered. At the beginning of the video, two dark zones are visible on the laptop screen on the right side of the graph - these are windows, and at the top at 0 degrees there is a mirror, to the left of which there is nothing particularly remarkable, but the graph has a stable bright zone.

An experiment in the courtyard showed a decrease in the background, on which radiation sources are clearly visible, which can be searched by moving with the locator and simultaneously calculating parallax. In the first video on the graph, a red circle marks an interesting phenomenon - the periodic appearance of a signal in a certain place - it can be searched and found. Probably, the search for stable sources of 10 GHz radiation is a path that has not yet been taken.

In addition to the passive measurement, we tried to measure the radiation from electrical appliances, and it turned out that the energy-saving gas-discharge mercury bulb, which is usual for everyone, constantly noise much higher than the background level, while the incandescent lamp is invisible to the measuring device. So there is always a reason and reason to think :)