Electronics, Radio & antennas

Cheap single-component RF filters.

Low, Band and High – pass filters are one of the major components when working with RF. Depending on the application, filters can reduse out noise and unwanted signals, or to limit a transmit signal to a pre-specified frequency band in order to prevent interfering with other signals around. Here I want to describe how to build simple and cheap…

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Astro tools, Electronics, Radio & antennas

Low noise and low cost amplifier for radio astronomy, 21 cm band.

21 cm band also known as Hydrogen line is one of the important bands in radio astronomy. Please read this wikipedia article if you not familiar with Hydrogen line. Nowadays even radio amateurs can observe this signal from the outer space, thanks to modern hardware. One of the most important part of the any receiver is antenna and input stage.…

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Radio & antennas

144 MHz Yagi-Uda antenna

Yagi–Uda antenna is a directional and pretty effective antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods. Best-known use of this type of antenna is as rooftop terrestrial television antennas, but it is also used for point-to-point fixed communication links and for long distance shortwave communication by shortwave broadcasting stations and radio amateurs.…

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