Регульований смуговий фільтр на основі кільцевих резонаторів для мікрохвильових застосунків

Abstract

The paper presents the principle of a microwave adaptive band-pass filter based on the cascade of ring resonators. The filter is performed as a planar microstrip technology with thickness of around 1 mm to ensure compactness of the device. The ring resonators, being a part of metamaterials, can be considered as an equivalence of an oscillator and is conventionally used in the microwaves. While a quite number of the filters with predefined parameters are well-known, the adaptive filters the throughput and output characteristics of which can be adjusted depending on the input ones is the topical problematic nowadays and, at least, for the closest future. We have investigated in the paper the possibilities of adjustment the considered filter’s transmission characteristics through the ring design, distance between them, and discussed other features, which have impact. For example, it allows expanding of the filter bandwidth from 250 to 60 MHz for simultaneous change of a distance between the adjacent rings. We have suggested the approach how to do the filter time-dependent. A varactor diode inserted into the gap of the middle ring is controlled with an independent external source and can adjust the filter bandwidth from 80 up to 140 MHz for the varactor capacitance variation from 16 to 6 pF (bias voltage variation from 1 to 7 V) that covers the existing communication networks, such as mobile generations, Bluetooth, Wi-Fi, etc. and can be applied for modern smart technologies of the Internet-of-Things for a remote control. It becomes possible because different sensing elements, such as photodiodes, Hall effect sensors, photoresistors, etc., can be exploited as the aforementioned external source.