System for filtering signals of high and low frequency bands, and relevant implementation device
AssigneeForem S.p.A.
InventorsEnzo C. D'Oro, Mario Bandera
Life of this patent
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Abstract
A filtering system for separating a composite signal containing two signals in different frequency bands: a high frequency signal and a low frequency signal. The composite signal to be separated is input into an inductive element in a high frequency filter section. The high frequency signal is immediately coupled by mutual induction with a resonant element of the high frequency filter section, the resonant element being designed so that the low frequency signal is not coupled because of the low value of its frequency. The low frequency signal is transmitted to low pass filter section which rejects any signal remaining in the high frequency band.
Claims10
A filtering system for separating two signals in difference frequency bands contained in a composite signal, a first one of the two signals to be separated being a low frequency signal in a frequency band extending from dc to 300 MHz, a second one of the two signals being a high frequency signal in a frequency band extending from 600 MHz to 15 GHz, said system comprising:
- a high frequency filter for receiving the composite signal to be separated, the high frequency filter being non-capacitive and including an inductive element through which both the high frequency signal and the low frequency signal pass, the high frequency signal being coupled from said inductive element to a resonant element of the high frequency filter by mutual induction therebetween, such that only the low frequency signal is transmitted to a low-pass filter, thereby avoiding undesirable effects caused by the passage of the high frequency signal into said low-pass filter.
A filtering system for separating two signals in different frequency bands contained in a composite signal, a first one of the two signals to be separated being a low frequency signal in a low frequency band, a second one of the two signals being a high frequency signal in a high frequency band, comprising:
- first filter means comprising an inductor disposed within a resonant cavity for inductively coupling only the high frequency signal;
- and
- second filter means coupled to said first filter means and comprising a plurality of stubs each having respective first ends electrically coupled to an end of said inductor, said stubs being disposed on a printed circuit board, said stubs each having a length equal to one quarter wavelength of the high frequency signal and each stub being separated by a distance equal to one quarter wavelength of the high frequency signal, said second filter means transmitting only the low frequency signal passing through said first filter means.
A composite filter system for separating a composite signal comprising a low frequency signal and a high frequency signal, said system including two sections, a first one of the two sections being a high frequency bandpass filter and a second one of the two sections being a low-pass filter, wherein:
- said high frequency bandpass filter comprises an input inductance and a resonant cavity magnetically coupled with the inductance, and
- said low-pass filter comprises a printed circuit including a plurality of stubs, said stubs each having a length of one fourth of the wavelength of the high frequency signal, said stubs each having a first end electrically coupled to said inductance of said high frequency bandpass filter.
Dependencies are inferred from the claim text.