Taajuusloukku

Taajuusloukku, or frequency trap in English, is a term used in telecommunications and signal processing. It refers to a circuit or system designed to block or attenuate a specific range of frequencies while allowing others to pass through. This is typically achieved using resonant circuits, such as LC (inductor-capacitor) circuits, which exhibit maximum impedance at their resonant frequency. By tuning the components of the LC circuit, a very sharp rejection band can be created, effectively "trapping" or filtering out the unwanted frequencies.

Frequency traps are commonly employed in various applications. In radio frequency engineering, they can be used to prevent interference between different communication channels or to suppress harmonic emissions from transmitters. They can also be found in audio systems to filter out specific noise frequencies or in measurement equipment to isolate signals of interest. The design of a frequency trap depends on the specific application, including the center frequency to be rejected, the bandwidth of the rejection, and the power handling requirements. Simple traps might consist of a single parallel LC circuit, while more complex filters can incorporate multiple stages to achieve a steeper roll-off and better attenuation. The effectiveness of a frequency trap is often measured by its Q factor, which indicates the sharpness of the resonance and thus the selectivity of the trap. A higher Q factor means a narrower rejection band and more precise filtering.