Playing with Filters

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1 Scope

Well, the title of this page is "Playing with Filters". This is meant literally. So I just wanted to play around a little with my HAMEG HMS-3010 and see how I could build a bandpass and how to understand the steepness of the flanks.

The background was an idea to construct a bandpass for the frequency range mainly between 1090 MHz (ADS-B) and about 1300 MHz (23 cm band). I wanted to suppress the lower signals quite effectively, and thus maybe create a filter for GPS experiments at 1575 MHz.

Here is a link to a nice page on capacitors, which may be useful for some of you:

2 Books

3 Filter Theory

Generally, a bandpass consists of a high pass and a low pass that play together.


In order to optimise it a little, i decided to use potentiometers, and since I did not have a 150 kOhm type, I used a fixed value 100 kOhm plus a 50 kOhm poti in series.


4 Measuring the filter


5 Building the Filter and Measurement setup

2019-01-19-bandpass4.jpg 2019-01-19-bandpass5.jpg

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