Eighth-mode Substrate Research Articles

Two Compact Bandpass Filters With Controllable Band Based on Eighth-Mode Substrate Integrated Waveguide

Two Compact Bandpass Filters With Controllable Band Based on Eighth-Mode Substrate Integrated Waveguide

SIW-based frequency-adjustable antenna for IoT-based duplex wireless devices

This paper proposes a compact and frequency-adjustable/reconfigurable dielectric (DR)-loaded eighth-mode substrate integrated waveguide (EMSIW) antenna for duplex wireless communications. The miniaturization of the resonators is realized using a rectangular slot and high isolation is achieved by keeping a reasonable space between them. The proposed design is simulated using a three-dimensional (3D) full-wave simulator, then analysed with a circuit model and finally validated experimentally. Frequency-reconfigurability in the suggested antenna is achieved by placing DRs with different permittivities in the designated holes that are realized in the open-ended portion of each resonator. Consequently, the lower- and high-resonant bands can be reconfigured from 4.70 to 5.23 GHz and from 5.55 to 6.34 GHz, respectively. It is worth mentioning that both resonant band can be independently reconfigured. Moreover, the inter-resonator coupling is always lower than −23.5 dB in the bands of interest. Furthermore, the peak realized gains are always greater than 4.7 dBi in the lower frequency band and 5.5 dBi in the higher one. The suggested antenna has stable radiation properties in both bands in all frequency ranges. Hence, this design is suitable for compact reconfigurable devices due to its compactness, large frequency ranges, stable radiation patterns, and high isolation.

Self-triplexing HMSIW antenna with enhanced isolation and extremely low frequency ratio

A self-triplexing antenna based on half-mode substrate integrated waveguide (HMSIW) cavity is proposed in this paper. The HMSIW cavity is designed as a combination of two eighth-mode substrate integrated waveguide (EMSIW) cavities and a single quarter-mode substrate integrated waveguide (QMSIW) cavity. The self-triplexing property is achieved by placing a narrow longitudinal slot on one of the EMSIW cavities and an annular cut on the QMSIW cavity. The proposed triplexer antenna operates at three distinct yet closely spaced frequencies 3.85 GHz, 4.12 GHz and 4.54 GHz with an extremely low frequency ratio (FR) of 1.18. The three operating bands are 3.82 - 3.88 GHz, 4.08 – 4.14 GHz and 4.51 – 4.57 GHz. The operating frequencies can be tuned independently by varying the dimensions of the slots. A minimum port isolation of 29 dB is achieved between the three cavities that contributes for self-triplexing property. The measured gain at three resonant frequencies is 6.02, 5.74 and 6.35 dBi, respectively. The proposed HMSIW self-triplexing antenna occupies a very small area of 0.14 λ02 (λ0 is the free space wavelength at the lowest operating frequency) and it is extremely useful for fixed wireless access and point-to-point commercial microwave applications.

Wideband Bandpass Filters Based on Eighth-Mode Substrate Integrated Waveguide and Microstrip Resonators

A class of wideband bandpass filters (BPFs) with two eighth-mode substrate integrated waveguides (EMSIW) and two microstrip resonators is presented in this brief. The quarter-wavelength microstrip resonator is connected to the hypotenuse side of EMSIW resonator, which is different from these filters with two EMSIW resonators sharing vias or iris windows. By introducing the quarter-wavelength microstrip resonators, the design flexibility can be improved with a compact size. Based on the proposed topology, a BPF centered at 4 GHz is designed and fabricated with fractional bandwidth (FBW) of 25%. The measured insertion loss within the passband is only 0.9 dB, while the return loss is better than 14.1 dB. To further improve the roll-off skirts and attain a better out-of-band rejection, a transmission zero (TZ) is generated with the mixed electric and magnetic coupling between two microstrip resonators. The measured FBW of the BPF with one TZ is 26.6%, whose center frequency is also at 4 GHz. The measured stopband rejection above the passband is better than 34 dB from 5.02 to 8.31 GHz. Good agreement between simulated and measured results validates the feasibility of the proposed BPFs.

A High-Order EMSIW MIMO Antenna for Space-Constrained 5G Smartphone.

This paper proposes a high-order MIMO antenna operating at 3.5 GHz for a 5G new radio. Using an eighth-mode substrate integrated waveguide (EMSIW) cavity and considering a typical smartphone scenario, a two-element MIMO antenna is developed and extended to a twelve-element MIMO. These MIMO elements are closely spaced, and by employing multiple diversity techniques, high isolation is achieved without using a decoupling network. The asymmetric EMSIW structures resulted in radiation pattern diversity, and their orthogonal placement provides polarization diversity. The radiation characteristics and diversity performance are parametrically optimized for a two-element MIMO antenna. The experimental results exhibited 6.0 dB and 10.0 dB bandwidths of 250 and 100 MHz, respectively. The measured and simulated radiation patterns are closely matched with a peak gain of 3.4 dBi and isolation ≥36 dB. Encouraged with these results, higher-order MIMO, namely, four- and twelve-element MIMO are investigated, and isolation ≥35 and ≥22 dB are achieved, respectively. The channel capacity is found equal to 56.37 bps/Hz for twelve-element MIMO, which is nearly 6.25 times higher than the two-element counterpart. The hand and head proximity analysis reveal that the proposed antenna performances are within the acceptable limit. A detailed comparison with the previous works demonstrates that the proposed antenna offers a simple, low-cost, and compact MIMO antenna design solution with a high diversity performance.

Compact filtering power divider using mixed quarter‐ and eighth‐mode substrate integrated waveguide resonant cavities with flexible design

In this paper, a series of filtering power dividers (FPDs) employing quarter-mode substrate integrated waveguide (QMSIW) and eighth-mode substrate integrated waveguide (EMSIW) resonant cavities have been first demonstrated. The proposed prototypes possess the merits of extremely miniaturized dimensions and relatively low insertion loss. Based on the detailed analysis and investigation of electromagnetic features and feeding types corresponding to the miniaturized SIW resonant cavities, two-order mixed QMSIW and EMSIW FPDs with electric coupling or magnetic coupling topologies are presented. In addition, multi-layered structures are implemented to decrease the footprints of the FPDs further. To attain a higher-order design and enhance the out-of-band rejection, a four-order multi-layered FPD with cross coupling mechanism is finally developed. For demonstration and verification, seven prototypes of the proposed FPDs operating at 4.8 GHz are meticulously designed, fabricated, and measured. All experimental results are in reasonable agreement with the simulated ones.

A Low-Profile Eighth-Mode SIW Antenna With Dual-Sense Circular Polarization, Enhanced Bandwidth and Simple Structure

A practical method, which based on eighth-mode substrate integrated waveguide (EMSIW), is investigated in this paper to design low-profile antenna with dual-sense circular polarization (CP) and enhanced bandwidth. First, an eighth-mode radiating cavities is presented and excited by single coaxial probe for size reduction and directional radiation. Then, two EMSIW antennas are placed symmetrically and a triangular parasitic patch is introduced between two EMSIW cavities. Attribute to the weakly coupled effect between the radiation aperture and triangular parasitic patch, dual-sense circular polarization characteristic and an additional resonance are acquired. When the triangular patch is transformed into a square parasitic patch, the current path on the parasitic patch is shortened, and a new resonance point is generated at 3.55 GHz. While the resonant mode of the two eighth-mode radiating cavities are almost unaffected and the CP bandwidth varies with the changed current path. Finally, a dual-sense CP EMSIW antenna with extended bandwidth and simple structure is designed and fabricated. The overall size of the fabricated prototype is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.57\lambda _{0} \times 0.54\lambda _{0} \times 0.02\lambda _{0}$ </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">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at 3.4 GHz). Measured impedance bandwidth is 10.5% from 3.24 GHz to 3.60 GHz with an isolation up to 11.6 dB and a maximal gain better than 5.74 dBic in two ports is also achieved. Moreover, the characteristics of dual-sense CP and the cross-polarization suppression capability of up to 20 dB in the main beam are obtained in 3.48-3.60 GHz.

Field Distributions Analyzed of Substrate Integrate Waveguide (SIW)

Abstract In this paper, the relationship of full-mode substrate integrated waveguide (SIW), half-mode substrate integrated waveguide (HMSIW), quarter-mode substrate integrated waveguide (QMSIW) and eighth-mode substrate integrated waveguide (EMSIW) has been presented. Firstly, the characteristics of full-mode SIW were derived according to its field distribution and the equivalent relationship between the full-mode SIW and rectangular waveguide. And the parameters of the remaining three SIWs are obtained with the same method of the full-mode SIW. The analysis of these SIWs can provide a design guideline of microwave devices in application, especially in small size system.

A Wearable Textile RFID Tag Based on an Eighth-Mode Substrate Integrated Waveguide Cavity

A novel wearable textile Radio Frequency Identification (RFID) tag based on an eighth-mode substrate integrated waveguide cavity is presented. Antenna size reduction for effective operation in the [865-870]-MHz RFID UHF band is obtained by exploiting the H-field symmetry planes of a cylindrical Substrate Integrated Waveguide (SIW) cavity. High isolation from the human body and excellent robustness with respect to variations in antenna-body distance are achieved using an energy-based design strategy, aiming to reduce ground plane size. The resulting tag exhibits very low manufacturing complexity and may be produced at low-cost. Design and simulations were performed using CST Microwave Studio, and a prototype of the tag has been manufactured and tested in a real environment.

Ultra-compact quasi-elliptic bandpass filter based on capacitive-loaded eighth-mode SIW cavities

AbstractThis paper reports a novel fourth-order quasi-elliptic bandpass filter (BPF) based on capacitive-loaded eighth-mode substrate integrated waveguide (CLEMSIW) cavities. The CLEMSIW cavity is constructed by the conventional eighth-mode SIW with two dielectric substrates and three metal layers; a metal via is employed to connect the middle and bottom metal layers. The middle metal layer achieves a large loading capacitance to shift the resonance frequency. The proposed filter is designed in a quadruple scheme, and two controllable finite-transmission zeros can be realized. For the demonstration, a prototype with a center frequency of 1 GHz and a fractional bandwidth of 10% was designed, fabricated, and measured. The measured results agree well with simulated ones. The proposed filter has advantages of ultra-compact size, high selectivity, and good stopband performances.

Realisation of compact quasi‐elliptic bandpass filters based on coupled eighth‐mode SIW cavities

A novel basic quasi-elliptic response bandpass filter in quadruplet based on coupled TE 101 -mode-based eighth-mode substrate integrated waveguide (EMSIW) cavities is proposed and analysed firstly. The negative cross coupling is achieved by the nature of coupled fringe electric-field components of the first and fourth cavities. Then, based on the proposed basic quadruplet structure, two methods using a step-impedance resonator and meandered feeding lines, respectively, are introduced and analysed to realise S-L coupling to improve the upper stopband performance further. Finally, two possible structures with quasi-inline and quasi-folded layouts, respectively, are proposed to realise sixth-order EMSIW filters. Five EMSIW filters are designed, fabricated, and measured to demonstrate and verify the proposed structures. The proposed filters have the advantages of compact size, good out-of-band rejection and realisation of higher-order filtering function. The size of the realised 4th-/6th-order filter is less than . The out-of-band rejection higher than 28 dB can reach 2.32 f 0 .

Analysis of Eighth-Mode Substrate-Integrated Waveguide Cavity and Flexible Filter Design

In this paper, a systematic research campaign on eighth-mode substrate integrated waveguide (EMSIW) filters is reported. The sizes of these EMSIW resonant cavities are only one-eighth or one-sixteenth of a conventional SIW resonant cavity. Two different coupling topologies, i.e., electric coupling and magnetic coupling, are employed between two EMSIW resonant cavities, which are analyzed theoretically via the response of the structure and the relationship between the cavities. Both coupling topologies enable structural variations that possess advantages and flexibility of the second-order EMSIW bandpass filters (BPFs) designing. By utilizing these basic coupling mechanisms, multilayer board technology, and other practical techniques, a class of triple-order SIW BPFs with the merits of compact size and high selectivity are demonstrated. Specifically, several triple-order EMSIW BPFs composed of pure EMSIW cavities or comprised by combining EMSIW and quarter-mode SIW cavities are simulated, fabricated, and measured for verification.

A Novel Miniature Single-Layer Eighth-Mode SIW Filter With Improved Out-of-Band Rejection

An ultraminiature two-pole bandpass filter based on the eighth-mode substrate integrated waveguide is proposed in this letter. The combination of a coplanar waveguide and circular-ring miniaturized element as a new feeding method is used to improve the out-of-band rejection by introducing two transmission zeros. The measured insertion loss and return loss of the filter operated at 690 MHz are 1.25 dB and better than 20 dB, respectively. The out-of-band rejection is better than 30 dB up to 3 GHz. The equivalent circuit, simulation, and measured results are consistent with one another. The overall size of the filter is $35 \,\,\text {mm} \times 35$ mm, which is equivalent to $0.08\lambda _{\mathbf {0}} \times 0.08\lambda _{\mathbf {0}}$ . A miniaturization factor of 98.8% is achieved.

A compact planar circularly polarized eighth-mode substrate integrated waveguide antenna

AbstractA compact and planar broadband circularly polarized (CP) eighth-mode substrate integrated waveguide (EMSIW) antenna is proposed in this paper. An isosceles right triangular waveguide with one electric sidewall (located on one of its catheti) and two magnetic sidewalls (located on the other two edges of the triangle) is presented to investigate the characteristics of the EMSIW. The closed-form mode solutions of the electromagnetic field components and the cut-off frequencies are derived for all propagating modes in this triangular waveguide. The simulated electromagnetic field distribution is consistent with the analytical results. The resonant frequencies of the EMSIW cavity are then determined. A CP antenna consisting of four EMSIW elements is designed, fabricated, and measured. The measured 3-dB axial ratio bandwidth of the antenna is 21.6% from 4.72 to 5.86 GHz. Within this frequency range, the measured reflection coefficient is below −10 dB, and the measured peak gain in circular polarization at broadside is 6.89 dBic at 5.1 GHz.

Coupled Eighth-Mode Substrate Integrated Waveguide Antenna: Small and Wideband With High-Body Antenna Isolation

A novel antenna design for wideband operation is presented, consisting of a system of two coupled miniaturized eighth-mode resonant radiating cavities with a low-complexity feeding network. The design methodology relies on the virtual magnetic boundaries along the symmetry planes of a rectangular waveguide resonator, for size reduction, and the frequency bifurcation of two tightly coupled resonators, for bandwidth enhancement. After discussing its operating principle, a prototype targeting wearable applications is designed, manufactured, and validated. Multiband operation is achieved with simultaneous coverage of the 2.4-GHz ISM band and the LTE-7 up- and downlink-bands. Measurements in free-space and on-body scenarios validate the antenna’s performance. A bandwidth of 414 MHz (16.2%) is measured, as well as a maximal gain of 4.7 dBi. The directive patch-like radiation pattern and the ground plane topology lead to high body-antenna isolation and good on-body performance. Impedance bandwidth and radiation pattern remain stable when the antenna is worn by a person and bent around a cylinder to mimic deformation.

Design of Compact Bandpass Filters Using Quarter-Mode and Eighth-Mode SIW Cavities

The contribution of this paper is to propose novel balanced and dual-band bandpass filters (BPFs), using quarter-mode (QM) and eighth-mode (EM) substrate integrated waveguide (SIW) cavities, for the size reduction of the overall circuit. Two balanced BPFs, which separately demonstrate a third-order Chebyshev response and a fourth-order quasi-elliptic response, are realized by properly choosing, feeding, and coupling those QMSIW and EMSIW cavities. Not only desired differential-mode operation within the passband, but also good common-mode suppression in a certain frequency range have been achieved. Furthermore, a dual-band BPF with improved out-of-band rejection is also realized by properly constructing the coupling topology of four EMSIW cavities. An additional source-to-load coupling path is introduced in this dual-band BPF to obtain more transmission zeros (TZs). The sizes of resonant cavities utilized in the above designs are only one-fourth or one-eighth of those rectangular ones in conventional designs, which lead to a significant reduction in the overall circuit size. All proposed designs have been fabricated and measured to verify simulation predictions. Based on the author’s knowledge, it is the first time using QMSIW and EMSIW for balanced filter designs, and dual-band filter designs with TZs.

Eighth-Mode Substrate Integrated Resonator Antenna at 2.4 GHz

In this letter, a linearly polarized eighth-mode substrate integrated waveguide (EMSIW) resonator antenna that operates at 2.42 GHz and can be used for commercial wireless LAN applications has been proposed. In comparison to its SIW resonator counterpart, this structure is reduced to 1/8 of its size, while still retaining competent performance characteristics and simple design. The proposed structure has been simulated using CST MWS to obtain the frequency response and radiation characteristics. This EMSIW antenna has dominant resonant frequency at 2.42 GHz and radiates with a gain around 5 dBi. The effect of variation of ground plane width has been studied. The structure has been implemented on FR-4 substrate, and the simulated and measured results are in good agreement.

Compact dual‐passband LTCC filter exploiting eighth‐mode SIW and SIW hybrid with coplanar waveguide

A compact dual-passband low-temperature ceramic con-fired (LTCC) filter is proposed. Its electrical size is reduced by exploiting an eighth-mode substrate integrated waveguide (SIW) and a conventional SIW hybrid with a coplanar waveguide (CPW). The filter is fabricated on multilayer ceramic, which makes the filter even more compact. The filter was fabricated and measured. The measured results show that the filter has dual-passband, the first passband is centred at 8.0 GHz with 0.95 GHz 3 dB bandwidth, and the second passband is centred at 11.1 GHz with 0.41 GHz 3 dB bandwidth. The filter has low passband insertion and sharp roll-off characteristics at the transition band. The volume of the filter is only 9.6 × 9.6 × 1.4 mm3.

Electrically Small Dual-Band Reconfigurable Complementary Split-Ring Resonator (CSRR)-Loaded Eighth-Mode Substrate Integrated Waveguide (EMSIW) Antenna

In this paper, we propose a novel electrically small dual-band reconfigurable antenna. By using a compact eighth-mode substrate integrated waveguide (EMSIW) structure, we designed a compact antenna. This antenna is capable of dual-band operation by additionally loading an electrically small complementary split-ring resonator (CSRR) structure. The EMSIW and CSRR structures are designed for satisfactory operations at bandwidths of 1.575 GHz [global positioning system (GPS)] and 2.4 GHz [wireless local area network (WLAN)], respectively. We load the CSRR with a varactor diode to achieve a narrow bandwidth and to enable the resonant frequency to continuously vary from 2.4 GHz to 2.5 GHz. Thus, we realize a channel selection function, which is used according to WLAN standards. Irrespective of the variation in the varactor diode voltage, the resonant frequency of the EMSIW is not varied, such that the antenna maintains a constant frequency at the GPS bandwidth even at different voltages. Consequently, as the DC bias voltage varies from 11.4 V to 30 V, the resonant frequency at the WLAN bandwidth continuously varies between 2.38 GHz and 2.5 GHz. We observe that the simulated and measured s-parameter values and radiation patterns are in good agreement with each other.

상보적 분할 링 공진기를 이용한 전기적으로 작은 1/8 모드 기판 집적형 도파관 안테나

본 논문은 기판 집적형 도파관(SIW: Substrate Integrated Waveguide)와 상보적 분할링 공진기(CSRR: Complementary Split Ring Resonator)를 기반으로 한 전기적으로 작은 안테나를 제안한다. 안테나의 전기적 크기는 CSRR과 기존 SIW의 1/8크기인 Eighth-Mode Substrate Integrated Waveguide(EMSIW)를 적용하여 줄일 수 있었다. EMSIW는 기존의 SIW와 비교하였을 때 공진 주파수는 유지하면서 단지 12.5 %의 크기를 차지한다. 또한, EMSIW 안에 CSRR을 회전함으로써 안테나의 방사 특성을 유지하면서 공진 주파수를 바꿀 수 있었다. CSRR을 <TEX>$0^{\circ}$</TEX>부터 <TEX>$360^{\circ}$</TEX>까지 회전시켜 공진 주파수를 4.74 GHz에서 5.07 GHz까지 변화를 줄 수 있었다. 단향성 방사 패턴이 발생하며, 그 최대 이득은 4.5 dBi에서 5.92 dBi로 관측되었다. Based on a substrate integrated waveguide(SIW) and a complementary split ring resonator(CSRR), electrically small antennas are proposed in this paper. Antenna's electrical size is reduced by introducing both CSRR and the eighth-mode substrate integrated waveguide(EMSIW). The EMSIW occupies only 12.5 % of the conventional SIW at the same dominant resonant frequency. In addition, the resonant frequency of the antenna is varied by rotating the CSRR on the EMSIW while keeping the same radiation patterns. The resonant frequency is changed from 4.74 GHz to 5.07 GHz by varying orientation of the CSRR from 0 to 360 degree. Unidirectional radiation patterns are observed and the measured peak gains are from 4.50 to 5.92 dBi.