6results about How to "Lower cutoff frequency" patented technology

The invention discloses a four-corner snakelike bridge broadband electromagnetic band gap structure, and belongs to the technical field of circuit microwaves. According to the structure, complementary split-ring resonator shape etching is carried out at the center, and the snake-shaped bridge structures are arranged between the adjacent units, so that the inductance between the electromagnetic band gap units is increased, low-frequency-band SSN is effectively suppressed, the bandwidth is relatively wide, and SSN of a stop band can be effectively suppressed. The four sides of the EBG structure are etched into rectangles, and adjacent elements are connected to form a bridge. Compared with a traditional L-bridge structure, the S-shaped structure is designed, so that the surface current path can be increased, and the equivalent inductance and the equivalent capacitance are increased. The gap between the resonant rings generates a gap current and generates a resonant circuit, so that the cut-off frequency can be effectively reduced and the width of a stop band can be improved. The ultra-wide band gap structure takes the suppression depth of-30dB as a standard, can reach an ultra-wide band gap of 23.8 GHz, is obviously superior to a conventional electromagnetic band gap structure, and can better suppress the noise of a synchronous switch.

The application provides a non-contact ECG signal collection foot ring sensor, which comprises a foot ring body and an ECG signal sensor arranged on the foot ring body, wherein the ECG signal sensor comprises an electrode composite layer, a first insulating layer, an electromagnetic shielding layer and a second insulating layer arranged in sequence, the electrode composite layer comprises a first electrode, a second electrode and a polarity layer arranged between the first electrode and the second electrode, the polarity layer comprises a polarity material of barium titanate and / or calcium titanate, the first electrode is used for being connected to an ECG collection circuit, the second electrode is arranged in suspension, and the electromagnetic shielding layer is grounded. The foot ring sensor of the application comprises the electrode composite layer, the electrode composite layer contains the polarity material of barium titanate and / or calcium titanate with high dielectric constant, and thus has high dielectric performance, can effectively improve the coupling capacitance between the skin and the electrode, and further reduce the capacitive reactance and total impedance, reduce the attenuation degree of the ECG signal in the coupling process, and improve the electric signal detection effect.

The invention discloses a negative group delay SSPP transmission circuit based on a PSO algorithm and an optimization method thereof, and belongs to the technical field of microwave engineering, the circuit comprises a dielectric substrate and a negative group delay SSPP transmission module arranged on at least one surface of the dielectric substrate; the negative group delay SSPP transmission module comprises an SSPP transmission line and a circuit structure; the SSPP transmission line forms an SSPP transmission section through a plurality of pixelated SSPP main body units which are periodically etched on the surface of the dielectric substrate along the signal propagation direction; the circuit structure comprises pixelated circuit units etched in gaps of adjacent pixelated SSPP main body units, and the pixelated circuit units are used for generating negative group delay. Pixel value distribution of the pixelated SSPP main body unit and pixel value distribution of the pixelated circuit unit are obtained through PSO algorithm optimization, and optimization targets comprise minimum cut-off frequency and minimum negative group delay, so that the SSPP transmission circuit generates negative group delay characteristics, and the cut-off frequency is reduced.

The application discloses an ultra-small low-pass artificial surface plasmon filter based on an interdigital structure, which comprises upper copper sheets and lower copper sheets which are correspondingly laid on the upper and lower surfaces of a base layer, the middle part of the upper copper sheet is provided with 3-5 groups of plasmon units connected in parallel, the input end and the output end at both ends are connected with the adjacent plasmon units through 1-3 groups of transition units; each group of plasmon units has an L-shaped structure, an inverted and mirrored F structure and a mirrored F-shaped structure located at the lower end side of the L-shaped structure; the upper end side of the L-shaped structure is connected with the inverted and mirrored F structure through a transverse copper sheet, and the inverted and mirrored F structure and the mirrored F-shaped structure form a channel with equal width; the transition unit is different from the plasmon unit in that the transverse size of the transition unit gradually increases and is smaller than the transverse size of the plasmon unit. The application has a simple and compact structure, can effectively reduce the asymptotic frequency, can reduce the overall size and is suitable for an ultra-small low-pass filter.

The present invention provides a multi-band coaxial four-ridged horn combined feed and a manufacturing method, which relate to the fields of satellite communication, remote sensing and telemetry, and radio astronomy. The feed includes a coaxial horn, the inner conductor of the coaxial horn is a plain wall horn, the plain wall horn is indented inward relative to the horn mouth of the outer conductor of the coaxial horn, the tail flange of the plain wall horn is connected to the tail short-circuit plate of the outer conductor of the coaxial horn, and the outer conductor of the coaxial horn and / or the plain wall horn are provided with 4 ridges, the angle between adjacent ridges is 90 degrees, and each ridge is provided with a probe perpendicular to the central axis of the plain wall horn, the probe passes through the outer conductor of the coaxial horn and the ridge, and is inserted into the outer wall of the plain wall horn, and the probe is externally connected to the SMA socket for feeding. The present invention has excellent electrical performance, compact structure, high design freedom, and a wide range of application scenarios, and can be used as a dual-frequency shared feed or a triple-frequency shared feed.

This invention discloses an array-type acoustic black hole ring vibrator and a broadband vibration absorption device for pipelines including the array-type acoustic black hole ring vibrator, belonging to the technical field of vibration reduction devices. The array-type acoustic black hole ring vibrator of this invention is fixed to the outside of an annular pipeline and includes several acoustic black hole structural units arranged in an array along the circumference of the annular pipeline. The distances between the outer and inner surfaces of each acoustic black hole structural unit and the radial central axis of the annular pipeline exhibit a smooth gradient change with a periodic variation, being larger at both ends and smaller at the center, forming an outer arc-shaped profile surface and an inner arc-shaped profile surface. A ring segment of constant thickness is also provided between every two acoustic black hole structural units. This invention can achieve lower frequency and wider frequency pipeline vibration suppression without changing the internal flow channel structure of the pipeline or causing any damage to the pipeline.