Low, Band, and High – pass filters are major components when working with RF. Depending on the application, filters can reduce output noise and unwanted signals or limit a transmit signal to a pre-specified frequency band to prevent interference with other signals. Here I want to describe how to build simple and cheap single-component (ceramic) filters for your DIY projects.
Category: Radio & antennas
Dish antenna for the amateur radioastronomy
In the previous article, I describe a low noise amplifier for the 21cm band. Today I want to show you a construction of the dish antenna where this amplifier was used.
Low noise and low cost amplifier for radio astronomy, 21 cm band
21 cm band, also known as the Hydrogen line, is one of the important bands in radio astronomy. Please read this Wikipedia article if you not familiar with the Hydrogen line. Nowadays, even radio amateurs can observe this signal from outer space, thanks to modern hardware. One of the most important parts of any receiver is the antenna and input…
Listening to aircrafts and receiving images from the satellites
In the previous article, we discussed how to calculate and build a simple Yagi-Uda antenna. Now it’s time to play with this antenna and receive some interesting signals.
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. The 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 long-distance shortwave communication by shortwave broadcasting stations and radio amateurs. This…