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High selectivity electrically tunable coaxial filter with constant absolute bandwidth

A high-selectivity, filter technology, applied in waveguide-type devices, circuits, electrical components, etc., can solve the problems of difficult tuning, high insertion loss and cost, limited to less than 12%, etc., to achieve high quality factor, low Insertion loss, the effect of reducing insertion loss

Pending Publication Date: 2019-05-07
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Tunable dielectric filters have attracted great attention due to their extremely high Q value, however, their tuning range is generally limited below 12% due to the fact that the field distribution is mainly concentrated inside the dielectric
Among the tuning components, the mechanical motor system or manual screw adjustment is conducive to maintaining a low insertion loss level within the tuning range, but both have the problem of slow speed regulation, and the mechanical motor system also has the disadvantages of large size and high cost; RF-MEMS A major challenge in device tuning is that it is difficult to achieve a large number of tuned states, and the hybrid integration of MEMS switches and capacitors often results in high insertion loss and cost

Method used

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  • High selectivity electrically tunable coaxial filter with constant absolute bandwidth
  • High selectivity electrically tunable coaxial filter with constant absolute bandwidth
  • High selectivity electrically tunable coaxial filter with constant absolute bandwidth

Examples

Experimental program
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Effect test

Embodiment 1

[0035] Such as figure 1 As shown, a highly selective electrically adjustable coaxial filter with a constant absolute bandwidth includes a metal cavity and a coaxial resonant rod located in the metal cavity, a frequency adjustment circuit, an input port, an output port and a PCB board, the A metal layer is arranged on the lower surface of the PCB, the metal layer is connected to the bottom surface of the metal cavity, the PCB board is embedded in the bottom surface of the metal cavity, a metal disc and a frequency adjustment circuit are arranged on the upper surface of the PCB, and one end of the coaxial resonant rod is connected to The top surface of the metal cavity is connected to realize a short circuit, and the other end is connected to the frequency adjustment circuit through a metal disc to form a resonator with adjustable frequency. The input port and the output port are connected with the coaxial resonant rod to realize power feeding to the coaxial resonator. The coax...

Embodiment 2

[0063] Such as Figure 2-Figure 4 As shown, this embodiment provides a second-order highly selective electric-tunable coaxial filter with a constant absolute bandwidth. The overall size of the circuit is W×L×H, specifically 23mm×47.5mm×48mm or 0.111×0.054 ×0.112λ g 3 ,λ g is the waveguide wavelength corresponding to the lowest frequency. The specific size is: w 1 =2.5mm, l=3.5mm, R=3mm, h 1 = h 2 = 4mm, h 3 =39.17mm, h 4 =10.5mm, d=7mm, Gap=11.4mm; capacitance value is 100pF, resistance value is 47kΩ.

[0064] Figure 5 and Figure 6 The results of simulation and actual measurement of the filter designed using the above parameters are given. The simulation is completed using the joint simulation of commercial electromagnetic simulation software ADS and HFSS of Agilent and ANSYS, and the actual test is done using a network analyzer 5071C and DC voltage source SPD3303x to complete. Figure 5 It is the transmission characteristic curve of the filter simulation and tes...

Embodiment 3

[0067] Such as Figure 7-Figure 9 As shown, the present embodiment provides a third-order high-selectivity electric-tunable coaxial filter with a constant absolute bandwidth, and there are three coaxial resonant rods arranged in an equilateral triangle. The overall size of the circuit is W×L×H, and the size is 38.5mm×53mm×46.1mm or 0.125×0.091×0.109λ g 3 ,λ g is the waveguide wavelength corresponding to the lowest frequency. The specific size is: w 1 = 3.3mm, w 2 = 4.25mm, w 3 =15.5mm, l 1 = 11 mm, l 2 =6.7mm, l 3 = 15mm, l 4 =23mm, R=3mm, h 1 = h 2 = 4mm, h 3 =37.27mm, h 4 =11.69mm, d=13.4mm; capacitance value is 100pF, resistance value is 47kΩ.

[0068] Figure 10 and Figure 11 The results of simulation and actual measurement of the filter designed using the above parameters are given. The simulation is completed using the joint simulation of commercial electromagnetic simulation software ADS and HFSS of Agilent and ANSYS, and the actual test is done using a...

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Abstract

The invention discloses a high selectivity electrically tunable coaxial filter with constant absolute bandwidth, which comprises a metal cavity, a coaxial resonance rod, a frequency adjusting circuit,an input port, an output port and a PCB (Printed Circuit Board), wherein the coaxial resonance rod, the frequency adjusting circuit, the input port, the output port and the PCB are arranged in the metal cavity, the lower surface of the PCB is provided with a metal layer and connected with the bottom surface of the metal cavity, the upper surface is provided with a metal disc and the frequency adjusting circuit, one end of the coaxial resonance rod is connected with the top surface of the metal cavity to realize a short circuit, the other end is connected with the frequency adjusting circuit through the metal disc to form a frequency adjustable resonator, the input port and the output port are connected with the coaxial resonance rod to realize the feed for the coaxial resonance rod. The electrically tunable filter is applicable to an LTE band of 698-960MHz, has the characteristics of constant absolute bandwidth, high selectivity, low loss and the like when the center frequency is tuned, and can be applied to the reconfigurable radio frequency front end of wireless communication.

Description

technical field [0001] The invention relates to a coaxial filter, in particular to a highly selective electrically adjustable coaxial filter with constant absolute bandwidth. Background technique [0002] Filters are the most commonly used passive devices in wireless communication systems, especially bandpass filters, which only allow signals within the passband to pass through, and filter out useless interference signals outside the band, which is important for ensuring good reception of communication equipment meaning. The ESC filter is equivalent to a combination of multiple filters with different frequencies. It not only has the above characteristics, but also can flexibly adjust the center frequency of the passband within a certain range. For example, in a software-defined digital radio frequency system, electronically tuned filters are used to replace large filter banks, which greatly saves installation costs and space; in addition, in order to improve the accuracy an...

Claims

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Application Information

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IPC IPC(8): H01P1/205
CPCY02D30/70
Inventor 章秀银杨莲徐金旭赵小兰
Owner SOUTH CHINA UNIV OF TECH
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