Distributed component RF filter

Abstract

This invention relates to a distributed element radio frequency (RF) filter. A distributed element RF filter includes one or more fully grounded half-wave resonators located between a first resonator and a second resonator, the first and second resonators being electrically coupled to corresponding input / output interfaces near their respective ends on a dielectric substrate. Each of the one or more half-wave resonators includes a U-shaped or ω-shaped resonator portion located between a first end and a second end, the first and second ends being electrically connected to a ground plane on a common side of the dielectric substrate. Each resonator has an electrical length nominally half the wavelength of the filter's center frequency. The filter may optionally include conductive caps above the resonators.

Description

Technical Field

[0001] This invention relates generally to radio frequency (RF) filters, and more specifically to distributed element RF filters including a grounded half-wave resonator. Background Technology

[0002] Distributed element RF filters generally consist of thick-film or thin-film resonators and other conductive elements deposited on a dielectric substrate. These filters are typically integrated with microstrip or other impedance-controlled transmission lines on printed circuit boards (PCBs) and are commonly used at or near the front end of communication and radar systems, where insertion loss, frequency selectivity, and power considerations are paramount. One such distributed element RF filter is a quarter-wave bandpass filter, which includes a partially grounded resonator with one end grounded (short-circuited) and the other end ungrounded (open-circuited). However, quarter-wave resonators tend to result in lower-than-desired insertion loss, stopband rejection, and deviation from the desired flat and low-loss passband. Therefore, it is desirable to provide improved distributed element RF filters with lower insertion loss, improved frequency selectivity, and one or more other desired characteristics. Utility Model Content

[0003] One aspect of this utility model relates to a distributed element radio frequency filter, the distributed element radio frequency filter comprising: a ceramic substrate having a ground plane on a first surface of the ceramic substrate; a first resonator located on a second surface of the ceramic substrate opposite to the first surface, the first resonator being electrically connected to a first input / output interface near a first end of the ceramic substrate; a second resonator located on the second surface of the ceramic substrate, the second resonator being electrically connected to a second input / output interface near a second end of the ceramic substrate opposite to the first end; and one or more intermediate resonators located on the second surface of the ceramic substrate, the one or more intermediate resonators being positioned... Between the first resonator and the second resonator, wherein each of the first resonator, the second resonator and the one or more intermediate resonators has an electrical length of half the wavelength of the center frequency of the distributed element RF filter, and wherein each of the first resonator, the second resonator and the one or more intermediate resonators includes a resonator portion between a first resonator end and a second resonator end, the first resonator end and the second resonator end being electrically connected to the ground plane via a conductive wall near a common side of the ceramic substrate, wherein each resonator at least partially surrounds a portion of the surface of the ceramic substrate in which the resonator is located.

[0004] Each resonator section includes a U-shaped resonator section.

[0005] Each resonator section includes an ω-shaped resonator section.

[0006] The first resonator, the second resonator, and the one or more intermediate resonators are all electrically connected to the ground plane through a common conductive wall.

[0007] The first resonator and the second resonator have a common electrical length, and the one or more intermediate resonators have a common electrical length.

[0008] The electrical lengths of the first resonator and the second resonator are greater than the electrical lengths of the one or more intermediate resonators.

[0009] The aspect ratio of the first resonator and the second resonator is smaller than the aspect ratio of the one or more intermediate resonators.

[0010] The distributed element RF filter is a thin-film multipole filter with a passband between 1 GHz and 60 GHz, and the one or more intermediate resonators have an unloaded quality factor greater than 400.

[0011] The distributed element radio frequency filter further includes a conductive cover fastened to the ceramic substrate and electrically connected to the ground plane, wherein the conductive cover is disposed on the second surface of the ceramic substrate.

[0012] A second aspect of this invention relates to a distributed element radio frequency (RF) filter, comprising: a dielectric substrate having a ground plane on one surface; a first resonator and a second resonator located on a surface of the dielectric substrate opposite to the ground plane, each of the first and second resonators being electrically coupled to a corresponding input / output interface near a corresponding end of the dielectric substrate; and one or more U-shaped or ω-shaped resonators located on a surface opposite to the ground plane and between the first and second resonators, each U-shaped or ω-shaped resonator including a first resonator end and a second resonator end, the first resonator end and the second resonator end being electrically connected to the ground plane via one or more conductors near a common side of the dielectric substrate, wherein each resonator has an electrical length of half the wavelength of the nominal center frequency of the distributed element RF filter.

[0013] The first resonator and the second resonator have a common electrical length, and the one or more U-shaped or ω-shaped resonators have a common electrical length.

[0014] The electrical lengths of the first resonator and the second resonator are greater than the electrical lengths of the one or more U-shaped or ω-shaped resonators.

[0015] The aspect ratio of the first resonator and the second resonator is smaller than the aspect ratio of the one or more U-shaped or ω-shaped resonators.

[0016] The distributed element RF filter further includes a conductive cover disposed on and spaced apart from the surface of the dielectric substrate on which the one or more U-shaped or ω-shaped resonators are located, and the conductive cover is electrically connected to the ground plane.

[0017] The distributed element RF filter is a thin-film multipole filter with a passband between 1 GHz and 60 GHz, wherein one or more U-shaped or ω-shaped resonators have an unloaded quality factor greater than 400.

[0018] A third aspect of this utility model relates to a distributed element radio frequency filter, the distributed element radio frequency filter comprising: a dielectric substrate, the dielectric substrate being disposed between a ground plane on one surface and a plurality of resonators on the opposite surface; the plurality of resonators comprising: a first resonator and a second resonator, the first resonator and the second resonator each being electrically coupled to a corresponding input / output interface near a corresponding end of the dielectric substrate; and one or more intermediate resonators located between the first resonator and the second resonator, each of the one or more intermediate resonators comprising a resonator portion between a first end and a second end, the first end and the second end being electrically connected to the ground plane via one or more conductors near a common side of the dielectric substrate.

[0019] Each of the plurality of resonators includes a resonator portion having a U-shape or an ω-shape.

[0020] The electrical lengths of the first resonator and the second resonator are greater than the electrical lengths of the one or more intermediate resonators.

[0021] The aspect ratio of the first resonator and the second resonator is smaller than the aspect ratio of the one or more intermediate resonators.

[0022] The distributed element radio frequency filter further includes a conductive cover disposed on and spaced apart from the surface of the dielectric substrate on which the plurality of resonators are located, and the conductive cover is electrically connected to the ground plane.

[0023] The distributed element radio frequency filter is a thin-film multipole bandpass filter with a passband between 1 GHz and 60 GHz, wherein each of the one or more intermediate resonators has an electrical length that is half the wavelength of the nominal center frequency of the bandpass filter. Attached Figure Description

[0024] The objects, features, and advantages of this invention will become more fully apparent when considered in conjunction with the following detailed description, which is accompanied by the accompanying drawings. The drawings depict only representative embodiments and implementations and are not intended to limit the application of the teachings of this invention.

[0025] Figure 1 This is a three-dimensional diagram of a representative distributed element RF filter.

[0026] Figure 2 yes Figure 1 A plan view of an uncovered RF filter.

[0027] Figure 3 It is a plan view of a distributed element RF filter that includes alternative resonators.

[0028] Figure 4 It is a planar diagram of a distributed element RF filter that includes another resonator.

[0029] Figure 5 It is a planar diagram of a distributed element RF filter that includes another resonator.

[0030] Figure 6 It is a planar diagram of a distributed element RF filter that includes another resonator.

[0031] Figure 7 It is a planar diagram of a distributed element RF filter that includes another resonator.

[0032] Figure 8 It is a plan view of a distributed element RF filter that includes another alternative resonator.

[0033] Figure 9 yes Figure 1 A bottom view of the ground plane of the RF filter.

[0034] Figure 10 This is a side view of a representative distributed element RF filter.

[0035] Figure 11 This is an end view of the distributed element RF filter, including the cover.

[0036] Figure 12Comparative analog passband diagrams of a prior art bandpass filter with a partially grounded quarter-wave resonator and a bandpass filter with a fully grounded half-wave resonator, according to the present invention, are shown.

[0037] Those skilled in the art will understand that the accompanying drawings are for simplicity and clarity and therefore may not be drawn to scale and may not include well-known features. The order in which actions or steps occur may differ from the order in which they are described. Unless otherwise stated, some or all of these actions or steps may be performed simultaneously. The terms and expressions used herein have the meanings understood by those skilled in the art, unless specifically assigned different meanings. Detailed Implementation

[0038] This invention generally relates to radio frequency (RF) filters, including microwave filters, and more specifically to distributed element RF filters comprising a grounded half-wave resonator located on a dielectric substrate that can be mounted on a printed circuit board (PCB) or some other host device or system. Such filters can be constructed as microstrip, stripline, or other impedance-controlled transmission lines. Representative distributed element RF filters are further described herein. In this specification, RF includes microwave frequencies.

[0039] Resonators and other conductors in distributed element RF filters can be deposited on a substrate as thick films or thin films using known fabrication processes. Thick film filter elements typically have a thickness ranging from 0.5 mils to 2.0 mils and can be formed by silkscreen printing metal paste onto the substrate, as well as other known and future processes. Thin film deposits can be patterned in various ways and deposited on the substrate by chemical vapor deposition, electron beam deposition, or sputtering, as well as other known and future deposition processes. Thin film filters typically have a thickness of approximately two skin depths. A "skin depth" is a depth at which the current density is approximately 1 / ℮ of the current density at the surface of the conductive film. Film thicknesses less than two skin depths may adversely affect insertion loss. Thicknesses of 3 to 5 skin depths are typical. Larger film thicknesses may not provide significant benefits and may reduce the accuracy of metal deposition. In a 10 GHz filter with a conductive film having good conductivity (e.g., copper, silver, gold, etc.), four skin depths are approximately 0.10 mils. Alternatively, resonators can be formed by patterns projected onto the substrate using laser or chemical etching. Resonators can also be formed from rolled or electrolytic conductor foils adhered to printed circuit boards or other substrates.

[0040] In one implementation, the distributed element RF bandpass filter includes a dielectric substrate between a ground plane at one surface of the substrate and a plurality of resonators at the opposite surface of the substrate. One or more intermediate resonators may be located between a first resonator and a second resonator, the first and second resonators being electrically coupled to corresponding input / output (I / O) interfaces near the corresponding ends of the substrate. In the bandpass filter, each of the one or more intermediate resonators may have an electrical length of half the wavelength of the nominal center frequency of the bandpass filter.

[0041] Each of the one or more intermediate resonators includes a resonator portion between a first resonator end and a second resonator end, the first resonator end and the second resonator end being electrically connected to the ground plane via one or more conductors near a common side of the substrate, wherein each of the one or more intermediate resonators at least partially surrounds a corresponding portion of the substrate on the surface where the resonator is located.

[0042] The dielectric materials used in the RF filters disclosed herein typically possess relatively high quality factors (Q) and stable temperature coefficients. Representative dielectric materials have Q factors greater than 400. One representative dielectric material is high-purity alumina (also known as "alumina") ceramic, which can have Q factors up to 5000 and a relative permittivity of approximately 10. Other known and future ceramics, among others, may also be used in the RF filters described herein.

[0043] Figure 1 It is a representative distributed element RF bandpass filter 100 configured as a microstrip transmission line, the microstrip transmission line including a dielectric substrate 200 between a plurality of resonators on one side and a ground plane on the opposite side. Figures 2 to 8 The resonator is best shown on the top surface 202 of the substrate, which is adjacent to the ground plane 206 (as shown in the image). Figures 9 to 11 The bottom surface 204 (as shown) is opposite to the substrate. Adjacent resonators are separated by gaps or spaces on the dielectric substrate. Figures 2 to 8 In this configuration, a first resonator 208 is electrically coupled to an input / output (I / O) interface 209 near a first end of the dielectric substrate, and a second resonator 210 is electrically coupled to an I / O interface 212 near a second end of the dielectric substrate. One or more fully grounded half-wave intermediate resonators are located between the first resonator 208 and the second resonator 210, which are electrically coupled to the I / O interfaces. In other embodiments, the filter may be configured as a stripline, wherein the resonators are sandwiched between a top ground plane and a bottom ground plane interconnected via conductive vias. Figures 2 to 8For example, by adding a second dielectric substrate and a second ground plane on top of the resonator, the filter can be configured as a stripline.

[0044] Electromagnetic coupling between resonators is a function of the dielectric gap between them. In embodiments including multiple intermediate resonators, reflections due to impedance mismatch can be reduced by providing a relatively large dielectric gap between one or more intermediate resonators and a relatively small dielectric gap between the last intermediate resonator and the resonators coupled to the I / O interface (e.g., 208 and 210). The filter order is related to the number of resonators. Figures 2 to 8 A third-order bandpass filter comprising three resonators is shown. Higher-order filters can be generated by adding additional resonators.

[0045] In one implementation, the distributed element RF bandpass filter is a thin-film multipole bandpass filter with a passband between 1 GHz and 60 GHz, and one or more intermediate resonators have an unloaded Q factor greater than 400.

[0046] exist Figures 2 to 8 In this configuration, each of one or more intermediate resonators typically includes a resonator portion 214 located between a first end 216 and a second end 218, the first end 216 and the second end 218 being connected to a ground plane via one or more conductors located near a common (i.e., identical) side of the substrate. In this configuration, each resonator is fully grounded and at least partially surrounds a portion 220 of the substrate surface where the resonator is located. The resonator portion 214 may have a U-shape or an ω-shape, etc., respectively, as shown in the diagram. Figure 2 and Figure 3 As shown.

[0047] exist Figures 2 to 8 In this configuration, each of the first resonator 208 and the second resonator 210 coupled to the respective I / O interfaces includes a resonator portion between a first end and a second end, the first and second ends being connected to a ground plane via conductors on one side of a dielectric substrate, as described herein. With this configuration, the first and second resonators of the RF filter, as well as one or more intermediate resonators, have the same shape. Alternatively, the first and second resonators may have a different construction or shape than one or more intermediate resonators. Typically, the resonators may surround a reference between I / O interfaces 209 and 212 (e.g., ...). Figure 1 The midpoint 201 shown is symmetrically arranged on the surface 202 of the substrate, wherein the resonator on one side of the reference is a mirror image of the resonator on the other side of the reference. The symmetrical arrangement of the resonators can improve filter performance.

[0048] Insertion loss can be reduced if the resonator is directly coupled to the ground plane via one or more conductors instead of capacitive coupling. Electrically connecting the first and second ends of the resonator to one or more conductors on the ground plane can form a conductive wall near the common side of the substrate. Figures 2 to 8 In this configuration, a first conductive wall 222 is disposed on a first outer side wall of the substrate, and a second conductive wall 224 is disposed on a second outer side wall opposite to the first outer side wall of the substrate. Figure 2 , Figure 3 and Figure 6 In this configuration, a conductive wall 222 extends between the ground plane and the first end 216 and the second end 218 of each resonator. Figure 4 and Figure 5 In this configuration, the first conductive sidewall 222 connects the ends 216 and 218 of the intermediate resonator to the ground plane, and the second conductive sidewall 224 electrically connects the ends of the first and second resonators, coupled to the I / O interface, to the ground plane. Figure 7 and Figure 8 In this embodiment, one or more conductors include a series of discrete vias 226 extending through the substrate adjacent to a first outer sidewall. The discrete vias electrically connect a first end 216 and a second end 218 of the resonator to a ground plane on opposite surfaces of the substrate. The conductive sidewalls or conductive vias may comprise a thick film or thin film deposited on a selected surface of the dielectric substrate (e.g., an outer sidewall or via).

[0049] The electrical length of a resonator typically depends on its physical length and the wavelength of the signal at a specific frequency or band. In one implementation, at least one or more intermediate resonators have an electrical length that is nominally half the wavelength of the center frequency of the bandpass filter, as described herein. The first and second resonators may also have an electrical length nominally half the wavelength of the center frequency. The term "nominal" means that the electrical length of the resonator may be 8% more or less than half the wavelength of the center frequency of the bandpass filter. Resonators connected to I / O interfaces may also have an electrical length nominally half the wavelength of the center frequency.

[0050] In one implementation, all resonators have the same electrical length. In other implementations, the resonators have different electrical lengths. For example, one or more intermediate resonators may have a common electrical length different from that of the first and second resonators. The electrical lengths of the first and second resonators connected to the I / O interface may be greater than the electrical lengths of one or more intermediate resonators to compensate for the electrical loads of the I / O interface, external devices, and other sources. Figures 6 to 8In this configuration, the first and second resonators coupled to the I / O interface have a common length longer than that of one or more intermediate resonators. Increasing the width of the resonators connected to the I / O interface relative to the width of one or more intermediate resonators can also compensate for electrical load. For example, the aspect ratio of the first and second resonators can be smaller than that of one or more intermediate resonators. In one implementation, one or more intermediate resonators have an aspect ratio not greater than 10.

[0051] exist Figures 2 to 8 In this configuration, the I / O interfaces are directly electrically connected to the resonator via corresponding conductive traces 211 and 213, respectively. Alternatively, the I / O interfaces can be coupled to the resonator via one or more intermediate capacitive elements. As used herein, the term "coupling" refers to capacitive coupling or direct electrical connection via conductive traces (i.e., non-capacitive coupling). Each I / O interface typically includes a corresponding castellation extending through the substrate 200 between the resonator and the surface containing the ground plane. Figures 2 to 9 The image shows a first groove 209 and a second groove 212 formed on corresponding endwalls of substrate 200. Alternatively, the grooves may be configured as through-holes located inside the endwalls. Each groove includes a flange portion on each of the opposite surfaces of the substrate. Figures 2 to 8 In this configuration, the flange portion on surface 202 connects to the corresponding conductive trace, and the conductive trace connects to the corresponding resonator. Figure 9 In this configuration, the flange portions 227 and 229 of the slot are separated from the ground plane 206 by corresponding gaps 228 and 230, respectively. By surface mounting the RF device in reflow soldering, wave soldering, or other assembly processes, the ground plane 206 and the flange portions of the slot can be electrically connected to corresponding conductors of the host device (e.g., contacts on a PCB). Alternatively, in other implementations, the I / O interface may be located on one side of the substrate or on the same surface as the resonator and electrically connected to the host circuitry via wire bonding or other conductor connection techniques. In RF and microwave filters, the characteristic impedance at the I / O interface is typically 50 ohms. However, in other filters, the impedance at the I / O interface may not be 50 ohms, depending on the application.

[0052] In some implementations, optionally, a conductive cap is placed above the resonator on the dielectric substrate, thereby effectively creating a waveguide. In some implementations, the conductive cap can improve filter performance. Figure 10 and Figure 11 In this design, the filter includes a cover 250 that covers a portion of a resonator on a substrate 200. The cover, made of metal or other conductive material, has a top wall 252 and opposing side walls 254 and 256 electrically connected to a ground plane via the conductive side walls. Figure 10In this configuration, the sidewalls of the cover are connected to the corresponding conductive sidewalls of the substrate. The ends of the cover may remain open, allowing a channel to exist beneath the cover.

[0053] Figure 12 A simulated passband plot 300 for a prior art 4-pole distributed element RF bandpass filter with a quarter-wave resonator is shown, and a similar plot for a 4-pole distributed element RF bandpass filter with a quarter-wave resonator is shown. Figure 2 The simulated passband curves of a representative 4-pole distributed element RF bandpass filter of the type of half-wave resonator shown and described herein are shown in Figure 310. Both filters comprise a 0.02-inch thick ceramic substrate with a dielectric constant of approximately 25. Both filters include a 0.1 mil thin-film metallization layer. The resonator of the quarter-wave filter is connected to the ground plane via a conductive via. The resonator of the half-wave filter is connected via... Figure 2 The metallized sidewalls of the type shown are connected to the ground plane. The half-wave filter has a higher Q factor than the quarter-wave filter, resulting in an insertion loss of approximately 1.7 dB for the half-wave filter, compared to approximately 2.1 dB for the prior art quarter-wave filter.

[0054] In one implementation, a distributed element radio frequency (RF) filter includes a ceramic substrate having a ground plane on a first surface and a first resonator and a second resonator on a second surface opposite to the first surface. The first resonator is electrically connected to a first input / output (I / O) interface near a first end of the ceramic substrate, and the second resonator on the second surface of the ceramic substrate is electrically connected to a second I / O interface near a second end opposite to the first end of the ceramic substrate. One or more intermediate resonators on the second surface of the ceramic substrate are located between the first and second resonators. Each of the first, second, and one or more intermediate resonators has an electrical length half the wavelength of the nominal center frequency of the filter. Each of the first, second, and one or more intermediate resonators includes a resonator portion between an end of the first and second resonators, the first and second resonator ends being electrically connected to the ground plane via a conductive wall near a common side of the ceramic substrate, wherein each resonator at least partially surrounds a portion of the surface of the ceramic substrate in which the resonator is located.

[0055] Each resonator section may include a U-shaped resonator section or an ω-shaped resonator section. The first resonator, the second resonator, and one or more intermediate resonators are electrically connected to the ground plane through a common conductive wall of a plurality of through holes configured to extend through the ceramic substrate or the metallized sidewalls of the ceramic substrate.

[0056] In another implementation, the distributed element radio frequency (RF) filter includes a dielectric substrate with a ground plane on its surface and a first resonator and a second resonator on its surface opposite the ground plane. Each of the first and second resonators is electrically coupled to a corresponding input / output (I / O) interface near a corresponding end of the dielectric substrate. One or more U-shaped or ω-shaped resonators are located on the surface of the dielectric substrate opposite the ground plane and between the first and second resonators. Each U-shaped or ω-shaped resonator includes a first resonator end and a second resonator end, which are electrically connected to the ground plane via one or more conductors near a common side of the dielectric substrate, wherein each resonator has an electrical length of half the wavelength nominally the center frequency of the filter.

[0057] A distributed element radio frequency (RF) filter includes a dielectric substrate sandwiched between a ground plane on one surface and a plurality of resonators on the opposite surface. The plurality of resonators includes a first resonator and a second resonator electrically coupled to corresponding input / output (I / O) interfaces near corresponding ends of the dielectric substrate, and one or more intermediate resonators located between the first and second resonators. Each of the one or more intermediate resonators includes a resonator portion between a first end and a second end, the first and second ends being electrically connected to the ground plane via one or more conductors near a common side of the dielectric substrate.

[0058] In the various distributed element RF filter implementations described herein, the first resonator and the second resonator may have the same common electrical length, and one or more intermediate resonators may have a common electrical length. The electrical length of the first resonator and the second resonator may be greater than the electrical length of one or more intermediate resonators. Furthermore, the aspect ratio of the first resonator and the second resonator may be less than the aspect ratio of one or more intermediate resonators.

[0059] The various distributed element RF filters described herein may optionally include a conductive cap fastened to the dielectric substrate and electrically connected to a ground plane, wherein the conductive cap is disposed on the surface of the dielectric substrate on which the resonator is located.

[0060] Any distributed element RF filter described herein may be a thin-film multipole filter with a passband between 1 GHz and 60 GHz, and as described elsewhere in this document, one or more intermediate resonators have an unloaded quality factor (Q) greater than 400.

[0061] Although this disclosure and its best mode have been described in a manner that establishes ownership and enables those skilled in the art to make and use it, and which is hereby considered to be the best mode thereof, it should be understood and recognized that many modifications and variations may be made thereto without departing from the scope and spirit of the invention, which is not limited to the described embodiments.

Claims

1. A distributed element radio frequency filter, characterized in that, The distributed element radio frequency filter includes: A ceramic substrate, wherein a ground plane is present on a first surface of the ceramic substrate; A first resonator is located on a second surface of the ceramic substrate opposite to the first surface, and the first resonator is electrically connected to a first input / output interface near a first end of the ceramic substrate. A second resonator located on the second surface of the ceramic substrate, the second resonator being electrically connected to a second input / output interface near the second end of the ceramic substrate opposite to the first end; and One or more intermediate resonators are located on the second surface of the ceramic substrate, the one or more intermediate resonators being positioned between the first resonator and the second resonator. Wherein, each of the first resonator, the second resonator, and the one or more intermediate resonators has an electrical length that is half the wavelength of the nominal center frequency of the distributed element RF filter, and Each of the first resonator, the second resonator, and the one or more intermediate resonators includes a resonator portion between the first resonator end and the second resonator end, the first resonator end and the second resonator end being electrically connected to the ground plane via a conductive wall near a common side of the ceramic substrate, wherein each resonator at least partially surrounds a portion of the surface of the ceramic substrate in which the resonator is located.

2. The distributed element radio frequency filter of claim 1, wherein, Each resonator section includes a U-shaped resonator section.

3. The distributed element radio frequency filter of claim 1, wherein, Each resonator section includes an ω-shaped resonator section.

4. The distributed element radio frequency filter of claim 1, wherein, The first resonator, the second resonator, and the one or more intermediate resonators are all electrically connected to the ground plane through a common conductive wall.

5. The distributed element radio frequency filter of claim 1, wherein, The first resonator and the second resonator have a common electrical length, and the one or more intermediate resonators have a common electrical length.

6. The distributed element radio frequency filter of claim 1, wherein, The electrical lengths of the first resonator and the second resonator are greater than the electrical lengths of the one or more intermediate resonators.

7. The distributed element radio frequency filter of claim 5, wherein, The aspect ratio of the first resonator and the second resonator is smaller than the aspect ratio of the one or more intermediate resonators.

8. The distributed element radio frequency filter of claim 1, wherein, The distributed element RF filter is a thin-film multipole filter with a passband between 1 GHz and 60 GHz, and the one or more intermediate resonators have an unloaded quality factor greater than 400.

9. The distributed element radio frequency filter according to claim 8, characterized in that, The distributed element radio frequency filter further includes a conductive cover fastened to the ceramic substrate and electrically connected to the ground plane, wherein the conductive cover is disposed on the second surface of the ceramic substrate.

10. A distributed element radio frequency filter, characterized by, The distributed element radio frequency filter includes: A dielectric substrate, wherein a ground plane is included on one surface of the dielectric substrate; A first resonator and a second resonator, the first resonator and the second resonator being located on a surface of the dielectric substrate opposite to the ground plane, each of the first resonator and the second resonator being electrically coupled to a corresponding input / output interface near a corresponding end of the dielectric substrate; and One or more U-shaped or ω-shaped resonators, said one or more U-shaped or ω-shaped resonators are located on a surface opposite to the ground plane and are located between the first resonator and the second resonator. Each U-shaped or ω-shaped resonator includes a first resonator end and a second resonator end, the first resonator end and the second resonator end being electrically connected to the ground plane through one or more conductors near a common side of the dielectric substrate. Each resonator has an electrical length that is half the wavelength of the center frequency of the distributed element radio frequency filter.

11. The distributed element radio frequency filter of claim 10, wherein, The first resonator and the second resonator have a common electrical length, and the one or more U-shaped or ω-shaped resonators have a common electrical length.

12. The distributed element radio frequency filter of claim 11, wherein, The electrical lengths of the first resonator and the second resonator are greater than the electrical lengths of the one or more U-shaped or ω-shaped resonators.

13. The distributed element radio frequency filter of claim 10, wherein, The aspect ratio of the first resonator and the second resonator is smaller than the aspect ratio of the one or more U-shaped or ω-shaped resonators.

14. The distributed element radio frequency filter of claim 10, wherein, The distributed element RF filter further includes a conductive cover disposed on and spaced apart from the surface of the dielectric substrate on which the one or more U-shaped or ω-shaped resonators are located, and the conductive cover is electrically connected to the ground plane.

15. The distributed element radio frequency filter of claim 10, wherein, The distributed element RF filter is a thin-film multipole filter with a passband between 1 GHz and 60 GHz, wherein one or more U-shaped or ω-shaped resonators have an unloaded quality factor greater than 400.

16. A distributed element radio frequency filter, characterized by, The distributed element radio frequency filter includes: A dielectric substrate, wherein the dielectric substrate is disposed between a ground plane on one surface and a plurality of resonators on the opposite surface; The plurality of resonators includes: A first resonator and a second resonator, each electrically coupled to a corresponding input / output interface near the corresponding end of the dielectric substrate; and One or more intermediate resonators located between the first resonator and the second resonator. Each of the one or more intermediate resonators includes a resonator portion between a first end and a second end, the first end and the second end being electrically connected to the ground plane via one or more conductors near a common side of the dielectric substrate.

17. The distributed element radio frequency filter of claim 16, wherein, Each of the plurality of resonators includes a resonator portion having a U-shape or an ω-shape.

18. The distributed element radio frequency filter of claim 16, wherein, The electrical lengths of the first resonator and the second resonator are greater than the electrical lengths of the one or more intermediate resonators.

19. The distributed element radio frequency filter of claim 16, wherein, The aspect ratio of the first resonator and the second resonator is smaller than the aspect ratio of the one or more intermediate resonators.

20. The distributed element radio frequency filter of claim 16, wherein, The distributed element radio frequency filter further includes a conductive cover disposed on and spaced apart from the surface of the dielectric substrate on which the plurality of resonators are located, and the conductive cover is electrically connected to the ground plane.

21. The distributed-element RF filter of claim 16, wherein, The distributed element radio frequency filter is a thin-film multipole bandpass filter with a passband between 1 GHz and 60 GHz, wherein each of the one or more intermediate resonators has an electrical length that is half the wavelength of the nominal center frequency of the bandpass filter.

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