Half mode substrate integrated waveguide (HMSIW) filter with adjustable central frequency and bandwidth

Abstract

The invention relates to a half mode substrate integrated waveguide (HMSIW) filter with adjustable central frequency and bandwidth. The HMSIW filter formed by laminating two layers of dielectric-slabs is utilized, the area of an upper-layer dielectric-slab is larger than that of a lower-layer dielectric-slab, a physical space is provided for loading of a tuning element, and the tuning of the central frequency and the bandwidth is achieved by loading a varactor; a metal layer of the upper-layer dielectric-slab is sunken, and a sunken part metal layer and a metal layer of the lower-layer dielectric-slab form a relatively high capacitance effect; the reduction of the resonant frequency is not dependent on the increase on the size of a resonant cavity any longer, the frequency is tuned by the varactor externally loaded and connected in parallel, a frequency tuning mode of an SIW structure is creatively achieved; and meanwhile, with the introduction of an HMSIW, the requirement of a modern radio frequency communication system on miniaturization is met, and the problem that a traditional cavity filter is difficult to tune by externally loading a tuning element is solved.

Description

technical field [0001] The invention belongs to the technical field of electronic information, and specifically relates to a radio frequency filter capable of realizing both a center frequency and a fully adjustable bandwidth. Background technique [0002] Since the 21st century, the rapid development of wireless communication technology has made spectrum resources more and more scarce. In order to make full use of very limited spectrum resources, technologies such as frequency hopping, spread spectrum, and dynamic frequency allocation have been widely used in wireless communication equipment, and there are A reconfigurable communication system supporting multiple communication formats is established. Tunable radio frequency filters (hereinafter referred to as tunable filters), as an indispensable device for these technologies and systems, have received more and more attention in recent years. In civil communication, the traditional fixed filter requires the combination of ...

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Problems solved by technology

[0003] The tunable filter design of the microstrip structure has been very common, but the cavity filter, whose structure is similar to a "sealed metal box", is difficult to be tunable by loading adjustable components, and the tuning of this type of filter is generally It is done through the tuning screw on the physical structure. A company once developed a stepper motor to control the tuning screw to realize the adjustable cavity filter for the mobile communication base station, but finally gave up the promotion due to the requirement of the reconfigurable communication system on the tuning speed. (Using a stepper motor to physically change the tuning screw position takes a lot of time, and the tuning time required for the tuning components of the ESC is usually at the ns level)

[0004] At present, both the adjustable center frequency and the preset bandwidth, the reconfigurable bandwidth and the fixed center frequency, and even the RF filters with independent adjustable frequency of the dual-pass band have been relatively mature, but at present, the center frequency and bandwidth can be realized at the same time. There are still relatively few research results on tunable filters. Fully tunable filters with center frequency and bandwidth can realize "tailor-made" communication services of various standards, which is the ultimate design goal of tunable filters.

In today's increasingly crowded spectrum, many practical applications have certain requirements for bandwidth, and it is difficult to use tuned filters with uncontrolled bandwidth. There is an urgent need to study fully tunable filters with excellent performance in frequency and bandwidth.

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