Microwave passive radar in the 10 GHz band

Description

The equipment for receiving satellite TV channels and an electric motor is a mobile device that scans radiation from the horizon in the 10 GHz range. The data is visualized, an article with video pictures.

Technical implementation

Cheap components are 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. The stable mount is welded from steel pipes, an electric motor and an axis around which the plate rotates is fixed on it. On the mount there is a controller that receives data from the rotating part and sends it to the com port of the computer on which the data visualization program is running. There are only two data streams: information about receiver rotation and measurement. The width of the lobe of the directional reception of a small parabolic plate is comparable with the value of 1 degree. For one revolution (approximately 1-1.5 seconds) there are approximately 400 12-bit measurements. Due to the relatively low signal-to-noise ratio for display on the screen, data is collected programmatically and averaged over several turns. To digitize the analog signal from the satellite head filter (converter), use the RF logarithmic detector / controller AD8313 and ADC MAX1236. For our amateur purposes, you can use a converter with any polarization and frequency appropriate to the diameter of the antenna.

Experiments

It was found that radiation from the walls of the houses is higher than the background. If the locator is installed inside the room, the glass windows are fixed by lowering the signal. Also, in a rustic brick house we saw incomprehensible sources of 10GHz radiation in the walls, and in the place where the mirror hangs, the signal level is lowered. At the beginning of the video on the laptop screen in the right part of the graph two dark zones are visible - these are windows, and at the top there is a mirror at the 0 degree mark, to the left of which there is nothing particularly remarkable, but there is a stable bright zone on the graph.
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The experiment in the yard 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 the parallax. In the first video on the graph, a red circle marked an interesting phenomenon - the periodic appearance of a signal in a certain place - it can be searched and found. Probably, the search for sustainable sources of 10GHz radiation is a path that has not yet been followed.

In addition to the passive measurement, we tried to measure the radiation from electrical appliances, and it turned out that the usual energy-saving gas-discharge mercury lamp constantly rustles noticeably above the background level, while the incandescent lamp is imperceptible to the measuring device. So there is always a sense and reason to think :)