Substrate Integrated Waveguide Bandpass Filter Research Articles

Air-filled substrate integrated waveguide bandpass filter based on miniaturized non-resonant node structure

Abstract This paper proposes an air-filled substrate integrated waveguide (AFSIW) bandpass filter with a miniaturized non-resonant node (NRN). The NRN structure is introduced between the three resonators, and its size is smaller than the resonator size, which can realize the NRN structure’s miniaturization and reduce the model’s size. The NRN size of this filter is 41% of the NRN size of the existing AFSIW filter. This filter also introduces a transmission zero (TZ) above the passband. The measured results show that the filter’s center frequency is 20.73 GHz, and the bandwidth is 0.86 GHz. The insertion loss in the passband is 0.95 dB, and the return loss is better than 23 dB. Due to the TZ in the upper stopband, the AFSIW filter obtained good selectivity.

A miniaturized and low-loss Q-band SIW bandpass filter based on evanescent-mode in wafer-level packaging process

This paper presents a miniaturized Q-band substrate integrated waveguide (SIW) bandpass filter (BPF) on a silicon-based wafer-level packaging (WLP) process. By incorporating capacitive quasi-coplanar waveguide (CPW) feeding structures and complementary split-ring resonators (CSRRs), the SIW operates in an evanescent-mode below the lower cutoff frequency and then achieves miniaturization. The efficient conversion of wave-modes, mutual excitation among multiple capacitive structures, and extremely short transmission paths, collectively resulting in the proposed BPF exhibiting low insertion loss. Furthermore, the area of fabricated filter has been reduced by 88.96 % compared to the requirement of the cutoff frequency. The measured results show that the minimum insertion loss is 1.24 dB, the return loss is better than 15 dB, and the 3 dB passband covers from 29.6 to 47.8 GHz (FBW is 47 %). These results indicate that, the proposed filter effectively solve the issues of large areas in SIW filters and high losses in silicon-based integrated or packaging processes.

A technique for the passband and stopband control of wideband band-pass substrate integrated waveguide (SIW) filters designed with elliptic stepped impedances

In this paper, a design technique based on a stepped impedance synthesis is proposed for the first time for the passband and stopband control of band-pass filters in substrate integrated waveguide (SIW) technology. The structure of the band-pass filters is implemented by means of elliptic patterns etched on the top side of the SIW, which work as impedance inverters. The design method consists of previously mapping the height of the elliptic patterns and the phase shift (cut-off angle) of the SIW lines, connected to the input and output ports of the ellipses, as a function of the passband and stopband characteristics of various stepped impedance SIW filters, to then select the design parameters of the band-pass SIW filter that achieve the desired frequency response. This new approach is applied to the design of two fourth-order Chebyshev stepped impedance band-pass SIW filters with different passband and stopband characteristics. One of the band-pass SIW filters is characterized by a fractional bandwidth FBW1 = 14.5% and a spurious-free range SFR1 = 2.8 GHz, while the other filter has a FBW2 = 22.3% and a SFR2 = 1.55 GHz. Both band-pass filters were designed with a SIW TE10 mode cut-off frequency and a higher passband cut-off frequency fixed at fcTE10 = 2.85 GHz and fc,H = 3.9 GHz, respectively. Electromagnetic (EM) simulations showed that the lower passband cut-off frequency fc,L can vary with respect to fc(TE10) by 13.6% and that the first spurious frequency can appear higher than fc,H by 69.3%. The measurement results agreed well with the EM simulations, thus confirming that this method can be useful to design high-performance wideband Chebyshev stepped impedance band-pass SIW filters with a high degree of control on the passband and stopband characteristics.

Self-Shielded Single-and Dual-Band Quad-Mode Substrate Integrated Waveguide Bandpass Filters Based on Mixed-Mode Cavity

Self-Shielded Single-and Dual-Band Quad-Mode Substrate Integrated Waveguide Bandpass Filters Based on Mixed-Mode Cavity

Wide-Stopband Substrate Integrated Waveguide Filters Based on Single-Mode Cavities With Multiple-Cross Slots

A novel design method for wide-stopband substrate integrated waveguide (SIW) bandpass filters (BPF) is proposed, which is realized by combining TE102-and TE101-based single-mode cavities with multiple-cross slots (MCSs). To demonstrate the proposed method, a planar SIW BPF with MCSs is proposed firstly. The ingenious MCSs have no effect on resonant modes, but have a great impact on non-resonant modes resulting in staggered their resonances. Thus, the stopband performance can be improved significantly and unload quality factors are not deteriorated simultaneously. To realize size-reduced wide-stopband SIW filters, a multiple-layer SIW filter is proposed on the basis of the planar filter. Finally, two SIW filters are fabricated and measured to verify the performance of the proposed SIW filters and the design method.

Compact Tri-Band SIW Bandpass Filters With High Selectivity and Controllable Center Frequencies Using Perturbation Structure

In this paper, two compact tri-band substrate integrated waveguide (SIW) bandpass filters (BPFs) with high selectivity and controllable center frequencies are presented based on the proposed tri-mode SIW resonant cavity perturbed by metallized vias. The resonant characteristics of the tri-mode SIW cavity are first analyzed, and the impacts of some key parameters on the resonant frequency are comparatively analyzed to further elucidate the flexible controlling of the vias perturbated SIW cavity structure. For demonstrating the superiority of the proposed tri-mode SIW cavity, a prototype of tri-band SIW BPF, centered at 11.18, 12.61 and 13.33GHz, is designed using one-layer substrate. In order to further reduce the occupied size, a tri-band SIW BPF with controllable center frequencies of 11.93, 13.21 and 14.12GHz, is constructed based on electric and magnetic coupling structure using two layers substrates. Both of the proposed triband BPFs exhibit six transmission zeros (TZs), resulting in good out-of-band rejections. The measured results agree well with the simulated ones.

An Inline Compact SIW Bandpass Filter With Quasi-Elliptic Response Using Microstrip Extracted-Pole Resonators

Two novel types of microstrip-based extracted-pole resonators are investigated in this brief, which are able to achieve a one-pole response with a transmission zero (TZ) created either below or above the passband. Resonance and transfer characteristics of the resonators are studied and discussed. And a detailed analysis is demonstrated by theoretical derivation and simulation. The application of the proposed extracted-pole resonators to an inline quasi-elliptic substrate integrated waveguide (SIW) filter is then presented, which exhibits a compact size and high selectivity with a TZ located on both sides of the passband. To verify the proposed concept, a filter prototype with a center frequency of 10 GHz is designed and fabricated. And the measured results show good agreement with the simulation, presenting a quasi-elliptic response with high selectivity.

TSV-based SIW bandpass filter with adjustable transmission zeros for D-band applications

A substrate integrated waveguide (SIW) bandpass filter with adjustable out of band transmission zeros based on through-silicon via (TSV) technology is proposed. The single-cavity degenerate mode is separated by the metal via-hole and the defect grounding structure, which is coupled with other cavities to generate transmission zeros with adjustable positions and increase the out of band roll-off rate. The results show that, the center frequency of the filter is 148GHz, the bandwidth is 6.5GHz, the minimum insertion loss is 1.4dB, and the return loss is better than 20.4dB.

A Design Method to Realize Manufacture-Friendly Millimeter-Wave Folded Substrate Integrated Waveguide Bandpass Filters

A design method for manufacture-friendly millimeter-wave (mm-Wave) folded substrate integrated waveguide (FSIW) bandpass filters (BPFs) is proposed in this brief. Based on conventional magnetic post-wall iris structure, etched parallel rectangular slots and an incompletely folded structure are introduced to serve as internal coupling structures. A design method is proposed to achieve lower fabrication errors and reduce the sensitivity to them by optimizing the coupling structures, thus, increasing the performance robustness. Then, an FSIW BPF based on the multilayer printed circuit board (PCB) is designed at Ka-band using the proposed method, and a conventional FSIW BPF is also designed as a reference. Both the two FSIW BPFs are fabricated, measured, and compared to confirm the effectiveness of the proposed method. The designed BPF using the proposed method exhibits a higher simulation-to-fabrication performance accuracy compared to the regular one, thus, should be a promising candidate for mm-wave applications.

Substrate-Integrated Waveguide Band-Pass Filter and Diplexer With Controllable Transmission Zeros and Wide-Stopband

In this brief, a substrate integrated waveguide (SIW) bandpass filter (BPF) with wide out-of-band rejection is researched and fabricated with the center frequency of 45.8 GHz and 3-dB FBW of 2.18%. Due to the exploitation of electronic excitation, higher order modes mismatch and orthogonal transmission, the simulated and measured out-of-band rejection is better than 20 dB with frequencies up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.6f_{0}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.4f_{0}$ </tex-math></inline-formula> , respectively. Diplexer with stopband suppression better than 30 dB up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.87f_{0}$ </tex-math></inline-formula> is proposed based on the theory of the proposed filter. Dual-mode resonator operating with TE301 mode (43.8 GHz) and TE103 mode (45.8 GHz) has been designed to provide the transition of two filter channels. High isolation better than 27 dB over the whole band can be achieved. Transmission zeros (TZs) are generated by spurious resonances under electrical excitation, resulting in high selectively of the passbands. Good agreements between simulations and measurements can be observed.

Novel Compact Half-Mode SIW Bandpass Filters Based on Quad-Mode Resonator

Novel wideband half-mode substrate integrated waveguide (SIW) bandpass filters based on the quad-mode resonator are proposed in this brief. The proposed half-mode SIW bandpass filter A is composed of two half-mode SIW structures and two T-shaped slots on the top surface. The coupling matrix topology and equivalent circuit model are presented to analyze the performance. The wide band of filter A is designed on the basis of quad-mode resonator (TE101, TE102, TE103, and TE104). Besides, it can generate one transmission zero on the upper stopband due to the equivalent inductance (connecting metallic line between two half-mode SIWs) and the mutual capacitance coupling between two SIWs according to the equivalent circuit model. On the basis of filter A, two open-ended microstrip lines are added near the input and output ports (This filter is named by filter B), which will introduce two transmission zeros (TZs) in the lower stopband. The introduced TZs can improve the out-of-band rejection on the lower sideband. The resonant frequencies of the four modes are controlled by the T-shaped slots on the upper metal plate, which can reduce the overall size, significantly. The proposed two filters have compact size of 47.9mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\times }\,\,14.9$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\times }\,\,2$ </tex-math></inline-formula> mm. The prototypes have been fabricated and measured, and the measured results have a good agreement with the simulated ones.

Ultra-compact half-mode substrate integrated waveguide bandpass filters with IRCSRR metamaterial on reinforced hydrocarbon polymer ceramic composites

In this work, metamaterial-enabled ultra-compact evanescent-mode half-mode substrate integrated waveguide (HMSIW) bandpass filters are developed by loading inner-rotary complementary split-ring resonator (IRCSRR) on reinforced hydrocarbon polymer ceramic composites substrate. In the proposed IRCSRR, inner-rotary slots are etched inside the conventional complementary split-ring resonator (CSRR) metamaterials to enhance the product of equivalent inductance and capacitance without occupying extra circuit area. Therefore, the proposed HMSIW-IRCSRR filters can obtain more size reduction with the same operation frequency as compared with the conventional CSRR-based ones. Similar as the conventional CSRR case, the evanescent-mode transmission below the dominant cutoff frequency of HMSIW can be produced by the negative permittivity effect of IRCSRR, and a transmission zero (TZ) at the upper stopband can be simultaneously generated by the mutual coupling between HMSIW and IRCSRR. Then, to improve the upper stopband performance, source-load coupling topology is utilized in the two-pole filters, which can produce multiple extra TZs. Meanwhile, multiple microstrip L/T-shaped open stubs are employed to introduce hybrid low-pass effect to further extend the upper stopband much wider. To demonstrate the availability of the aforementioned concepts, a series of HSMIW-IRCSRR filters are experimentally designed, fabricated and verified. Measured results shows that both ultra-compact sizes and excellent frequency-selecting performance are achieved simultaneously, as well as good agreement with simulations, all of which illustrating quite good promises for the practical radio frequency and microwave applications.

Co‐design of a low noise amplifier with compact substrate integrated waveguide bandpass filtering matching network

This article presents a co-design of a low noise amplifier (LNA) and bandpass filter (BPF) input matching network (IMN) based on quarter-mode and one-eight-mode substrate integrated waveguide (SIW) cavities. The transmission zeros (TZs) of the proposed BPF IMN occur in the stopband and demonstrate improved frequency selectivity compared to conventional methods. Our design can reduce the complexity and circuit sizes of receiving BPFs and LNAs in communication systems, and improve the receiving performance of radio frequency (RF) front-end circuitry. Three different LNAs were fabricated and tested. The proposed LNA features a three-stage compact-size SIW BPF IMN at a center frequency (f0) of 8 GHz. The proposed LNA with a compact SIW BPF IMN exhibits better electrical performance than a conventional LNA (CLNA) with a full-mode (FM) SIW BPF. We found that the small signal gains at f0 of the standalone CLNA, FM SIW BPF cascaded with CLNA, and the proposed LNA were 15.69, 14.72, and 15.18 dB, respectively. The measured noise figure (NF) at f0 of CLNA was 0.86 dB, while the NF of the FM SIW BPF cascaded with CLNA was 2.23 dB, and the NF of the proposed LNA at f0 was 1.71 dB. In addition, the circuit size of the proposed LNA is 48% smaller than that of an FM SIW BPF cascaded with CLNA.

Varactor–Graphene-Based Bandpass Filter With Independently Tunable Characteristics of Frequency and Amplitude

This article presents a frequency–amplitude independently tunable bandpass filter (BPF). The filter uses an electrically tunable coaxial substrate integrated waveguide (SIW) resonator, which has a compact size and a constant fractional bandwidth (FBW). The surface-gap coaxial SIW resonator is loaded with eight varactors and a thin graphene sheet at the top and bottom, respectively, which results in possessing independent tuning characteristics of frequency and quality factors. The variable capacitance values of the varactor are used to achieve frequency reconfigurability, and the graphene located on the bottom surface of the resonator is equivalent to a tunable lumped resistor used to control the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -factor. In addition, detailed steps of BPF design are provided. For validation, a prototype third-order varactor–graphene-loaded multitunable coaxial SIW BPF is fabricated. The measurements show that within the tunable range of the varactors, the proposed filter can be tuned from 0.68 to 1.03 GHz with 5% ± 0.2% 1-dB FBW and the insertion loss of passband can be continuously tuned over 2.68–6.37 dB. The frequency tuning and amplitude tuning functions are not dependent on each other. Over the frequency tuning range, the transmission amplitude at an arbitrary center frequency can be dynamically tuned by controlling the bias voltage applied to the graphene.

Millimeter‐wave substrate integrated waveguide bandpass filters based on stepped‐impedance E ‐shaped defected ground structure s

Millimeter‐wave substrate integrated waveguide bandpass filters based on stepped‐impedance <scp>E</scp> ‐shaped defected ground structure <scp>s</scp>

Low Profile Dielectric Rod Tuned Reconfigurable Band Pass Filters

A novel low profile mechanical tuning technique is introduced in this paper to change the center frequency of substrate integrated waveguide (SIW) based reconfigurable bandpass filters (BPF), by loading dielectric rods of different permittivity in resonant cavities and coupling apertures. The technique is simple, cost-effective (rods are machined from conventional substrates), and the same physical structure provides a wide frequency tuning. First, the tunability of center frequency of the SIW cavity resonator is theoretically explained and then estimated with the help of full-wave 3D EM simulator and electrical equivalent circuit. This concept is extended to the tuning of coupled resonator BPF loaded with dielectric rods followed by the analysis of maintaining constant bandwidth. Following the analysis technique, the tunability concept is studied for different arrangements of dielectric rods inside the SIW BPFs. The characteristics of the fabricated filters are experimentally validated. It is shown that center frequency tunability can be achieved by simply varying the permittivity of all the dielectric rods simultaneously. The proposed technique is further extended for obtaining wider tunability and constant bandwidth by using dielectric rods of dissimilar permittivities from a look up table. These designs demonstrate a simple and cost-effective passive tuning technique achieving high Q-factors in the range of 102–210.5, lowest insertion loss <2dB above 10 GHz, and wide tuning bandwidth in X-band. The reconfigurable filters are developed for advanced high-speed, long-distance, and fixed wireless connectivity in a rural area at a low cost. The technique can also be used for temperature compensation and overcoming fabrication uncertainty.

A Balanced Tri-Band Substrate Integrated Waveguide Bandpass Filter With High Selectivity

This paper proposed a balanced tri-band bandpass filter (BPF) with high selectivity based on substrate integrated waveguide (SIW) technology. The tri-band filtering response and multiple transmission zeros (TZs) are attained by elaborately merging cascaded quadruplet (CQ) topology and split topology. The proposed balanced tri-band bandpass filter is designed, which integrates high selectivity differential-mode (DM) transmission and good common-mode suppression by cleverly placing TE102-mode SIW cavity on the symmetric plane. To verify the proposed concept, a prototype of balanced tri-band BPF operating at 9.33, 9.67, and 10.02 GHz has been implemented. Measured results show eight TZs at out of DM passbands and more than 35 dB CM suppression within the DM passbands, which agree well with the simulated results.

A W-Band Compact Substrate Integrated Waveguide Bandpass Filter With Defected Ground Structure in CMOS Technology

This brief proposes the first on-chip bandpass filter (BPF) based on substrate integrated waveguide (SIW) for W-band applications. Slot-loaded, folded ridge and quarter mode technology is used to reduce the cavity size. The coupling characteristic of two folded ridged quarter mode substrate integrated waveguide (QMSIW) cavities implemented in CMOS technology is investigated. A simplified equivalent lumped-element circuit model of the proposed wide-band BPF approach is provided and applied to study the coupling characteristic of slot-loaded folded ridged QMSIW cavity. Then, a novel coupling method using a defected ground structure is proposed to realize a proper coupling intensity for BPF design. Finally, the proposed BPF design is implemented in a commercial complementary metal-oxide-semiconductor (CMOS) technology, fabricated, and measured. The active size of the proposed cavity resonator is only 405 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times185\,\,\mu \text{m}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.22{\lambda }_{\mathrm{ g}} \times 0.1 \lambda _{\mathrm {g}}$ </tex-math></inline-formula> ), and the measured insertion loss ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert|\text{S}_{21}~\vert|$ </tex-math></inline-formula> ) is 3.15 dB with a central frequency of 85.5 GHz.

Comparison of post and iris substrate integrated waveguide band-pass filters for X-Band applications

The substrate integrated waveguide (SIW) has been proposed as a reliable alternative to the rectangular waveguide due to its small size, low cost, high performance, ease of manufacturing and simplicity of integration with other microwave components. This paper focuses on SIW band-pass filters and presents their design procedure in details. The methodology is applied to post and iris SIW filters working at X-band with different orders, responses and bandwidths. Two prototypes of third-order post and iris SIW filters are fabricated and measured with a vector network analyzer. The filters are designed to work at 10 GHz center frequency and 500 MHz bandwidth. The simulation results and measurement results of the post and iris SIW filters are compared. In the simulations lower than 0.9 dB insertion loss and better than 20 dB return loss is observed in the pass-band of the filters. The post filter exhibits lower insertion loss and higher reflection loss at the stop-band of the filter. With their low cost, small size, ease of manufacturing, high performance and integrability with other components, both of the demonstrated X-band SIW filters are very versatile and well suited for a variety of market applications, including radars and satellite communications.

Design and Analysis of Compact 5th Mode Balanced Substrate Integrated Waveguide Band-Pass Filter for 39 GHz

This paper presents a balanced fifth-order Substrate Integrated Waveguide (SIW) band-pass filter operating at 39 GHz. The filter uses the balanced nature of the SIW resonators and the odd-mode property of the TE102 mode. Five rectangular resonators have been used to develop a fifth-order band-pass filter and the couplings between them with the external quality factors have been determined. The filter yields a good response in the KA band of the electromagnetic spectrum. It has a smaller footprint and operates at a higher frequency range compared to other filters with the same technology. The Common-Mode (CM) signal has been effectively suppressed to more than -30 dBs throughout the considered range. The return loss of -30 dBs and an insertion loss of -4 dBs for the Differential-Mode (DM) operation are achieved at the operating frequency of 39 GHz. The half-mode operation of the filter has been also implemented and the results have proven to be satisfactory.