Dielectric Bandpass Filter Research Articles

Wideband circularly polarized high accuracy survey active antenna for global navigation satellite systems applications

AbstractThis letter presents a new circularly polarized (CP) active antenna for global navigation satellite systems (GNSS) operating in the L1‐band (1.164–1.28 GHz) and L2‐band (1.525–1.615 GHz). The active antenna consists of a passive antenna and a two‐channel low‐noise amplifier (LNA) circuit. To achieve wideband coverage of the L1/L2 bands while maintaining a low profile, a new electroplating process is utilized in fabricating the passive antenna. Additionally, to realize CP performance, the passive antenna is sequentially fed by four ports with a wideband feeding network. To minimize phase variations, a 90° phase shifter loaded with open‐short‐stub is integrated into the feeding network. Furthermore, to improve noise immunity, out‐of‐band rejection, and amplify GNSS signals, the LNA circuit cascades two‐stage dielectric bandpass filters and three‐stage LNAs. Consequently, the circuit features a low noise figure of below 1.65 dB, a maximum out‐of‐band rejection level of 60 dB, and a stable active gain of 30 dB. The performance of the active antenna is evaluated in an outdoor open field using a GNSS receiver.

High quality of LiMg0.9Zn0.06Ni0.04PO4-TiO2 microwave ceramic and its application for 5G dielectric waveguide bandpass filter

A new microwave dielectric composite ceramic (1-x) wt%LiMg0.9Zn0.06Ni0.04PO4-x wt%TiO2 (0 ≤ x ≤ 18 wt%) was synthesized in the low sintering temperature range of 850 °C − 975 °C by the solid-state reaction method. The XRD diffractogram confirmed the coexistence of LiMg0.9Zn0.06Ni0.04PO4 and TiO2, and no second phase was detected. Due to their opposite τf values, the τf values of LiMg0.9Zn0.06Ni0.04PO4 solid solution ceramics were adjusted by adding different volume fractions of TiO2. The composite ceramic with x = 15 wt% sintered at 975 °C shows desirable microwave dielectric properties of εr∼10.30, Q×f ∼ 58,400 GHz (tan δ = 2.093 ×10−4), and τf ∼ + 4.04 ppm/ °C (at ∼12 GHz). Based on the 85 wt% LiMg0.9Zn0.06Ni0.04PO4-15 wt% TiO2 ceramics, a fourth order dielectric waveguide filter filled with composite ceramics is designed and packaged for the RF front-end of the China Mobile 5 G base station. The test results show that the center frequency of the filter is 4.65 GHz, the working bandwidth is 300 MHz, the filter has a good out of band rejection capability, and the insertion loss in band is 0.18 dB. Combined with the filter test data and material performance, the designed dielectric waveguide filter meets the communication requirements of the base station, and the higher Q×f microwave dielectric ceramic material can achieve low insertion loss and excellent frequency selection performance of the filter.

A Fourth-order Dielectric Narrow-band Bandpass Filter Using Coaxial Resonator

In this paper, a compact fourth-order dielectric bandpass filter is proposed. The filter adopts the mode of linear coupling and is composed of four coaxial resonators and two coupling slots, which are fed by two probes, and the four coaxial resonators are resonated to form a passband. The resonant frequency can be controlled by the radius and height of the resonators, and the inter-cavity coupling is controlled by the width of the coupling windows formed by the coupling slots. At last, the simulation results of the filter show that the filter has narrow bandwidth and good in-band matching performance and out-of-band suppression.

Spectrally pure far-UVC emission from AlGaN-based LEDs with dielectric band pass filters

AlGaN-based far ultraviolet-C (UVC) light emitting diodes (LEDs) with a peak emission wavelength below 240 nm typically show a long-wavelength tail at >240 nm that is detrimental to the use of the devices for skin-friendly antisepsis. We present the development of far-UVC LEDs with reduced long-wavelength emission using a HfO2/SiO2-based distributed Bragg reflector (DBR) filter. When the DBR filter is directly mounted on an LED package, the long-wavelength emission around 250 nm is reduced by two orders of magnitude while the transmitted output power is reduced down to 18%–27% of the initial value for DBR filters with cut-off wavelengths at 237–243 nm. As the transmission through the DBR filter depends strongly on the angle of incidence of the radiation, the transmitted output power of the spectrally pure far-UVC radiation can be doubled when an additional collimating lens is used on top of the LED package before passing through the filter.

Switchable Induced-Transmission Filters Enabled by Vanadium Dioxide.

An induced-transmission filter (ITF) uses an ultrathin metallic layer positioned at an electric-field node within a dielectric thin-film bandpass filter to select one transmission band while suppressing other bands that would have been present without the metal layer. We introduce a switchable mid-infrared ITF where the metal can be "switched on and off", enabling the modulation of the filter response from a single band to multiband. The switching is enabled by the reversible insulator-to-metal phase transition of a subwavelength film of vanadium dioxide (VO2). Our work generalizes the ITF─a niche type of bandpass filter─into a new class of tunable devices. Furthermore, our fabrication process─which begins with thin-film VO2 on a suspended membrane─enables the integration of VO2 into any thin-film assembly that is compatible with physical vapor deposition processes and is thus a new platform for realizing tunable thin-film filters.

A Dual-Mode Monoblock Dielectric Bandpass Filter Using Dissimilar Fundamental Modes

In this article, a novel dual-mode monoblock dielectric resonator (MDR) for compact monoblock dielectric bandpass filters is presented and put into practical use for the first time. In the dual-mode resonator, two dissimilar TEM modes are generated by forming two perpendicular metalized blind holes in a silver-coated cuboid-shapes dielectric block. The resonator can maximize the space utilization with up to 50% volume reduction while maintaining a wide spurious-free frequency band. The coupling of the two modes in such a resonator can be effectively controlled by one or more partial-height metalized posts. A convenient input/output (I/O) coupling scheme for surface-mount applications is introduced, and versatile coupling arrangements for realizing various filter characteristics are presented. To demonstrate the proposed filter miniaturization technique, a six-pole inline bandpass filter with one pure imaginary transmission zero (TZ) in a 3.5-GHz band is electromagnetic (EM) designed, and a ten-pole symmetric bandpass filter with two pure imaginary TZs in a 2.6-GHz band of fifth-generation (5G) new radio (NR) frequency band is designed, prototyped, and tuned. Experimental results show that the proposed dual-mode MDR filter can obtain an acceptable RF performance for 5G applications with a significant volume reduction compared to existing single-mode solutions.

Modal model and design of SINRD bandpass filter with LSE 01 fundamental mode

This paper presents an improved substrate integrated non-radiative dielectric (SINRD) bandpass filter design. The LSE01 (Longitudinal Section Electric) mode is used as fundamental mode, which allows substrate height reduction compared to classical lowest LSM (Longitudinal Section Magnetic mode). A new modelization is proposed to characterize such a bandpass filter using the circuits equivalent method. Simulation results are successfully compared to finite element software results. In the design, permittivity choices are justified through a sensitivity analysis to meet the bandpass filter requirements. Finally, the SINRD bandpass filter is synthesized by drilling an air hole pattern in the dielectric substrate. This new filter is characterized by simulations and measurements.

Cross‐coupled dielectric waveguide filter

A cross-coupled dielectric waveguide filter based on blind holes and via holes is proposed in this study. Using a unique all-hole design, a fourth-order cross-coupled dielectric waveguide bandpass filter is realized by drilling via holes or blind holes in a square dielectric waveguide, followed by coating the surface with thin metal. Magnetic coupling is realized using two blind holes located symmetrically above and below each other. Further, electrical coupling is realized using a combination of two blind holes located symmetrically above and below each other and an interconnecting via hole. Both types of coupling are analyzed and designed. Moreover, a circular via hole is provided in the middle of the square cavity to suppress the parasitic response of the filter. Coupling debugging holes, resonant debugging holes, and feed holes are realized using shallow blind holes, thereby alleviating the process of manufacturing and debugging. The structure of the designed filter is discussed, simulated, manufactured, and measured. The results show that the proposed filter has a center frequency of 3.5 GHz, an insertion loss of less than 0.5 dB, a return loss of less than 15 dB, and a relative bandwidth of 5%, exhibiting excellent performance that includes two out-of-band transmission zeros.

Diffraction of Electromagnetic Waves on a One-Dimensional Strip Conductor Grating Located at the Interface Between Dielectric Media

Analytical formulas are derived for the transmission and reflection coefficients of electromagnetic E- and H-waves incident at an arbitrary angle on a one-dimensional strip conductor grating located at the interface between two dielectric media. The feasibility of adjusting the grating reflectivity within wide limits by varying its design parameters is demonstrated, which allows these structures to be used in multilayered dielectric bandpass filters.

On the thin film optics of a Cassegrain telescope

Optical interference thin films designed and fabricated for use in a Cassegrain telescope were deposited by ion-beam-assisted deposition. The optical parameters of optical interference filters array and the protection layers of silver reflector were simulated and optimized by using admittance loci analysis. The patterned multispectral assembly containing blue, green, red, near infrared, and panchromatic multilayer high/low alternated dielectric band-pass filter arrays in a single chip was fabricated by photolithography process. The corresponding properties of the films were measured by in situ optical monitor and spectrometry. It was found that the average transmittances were above 90% for the multispectral assembly, with a rejection transmittance of less than 1% in the spectral range of 350–1100nm. The average reflectance of the large area silver mirror (with three layers protective interference coating) is boosted above 99% in visible spectrum. In addition, the equivalent admittance of the three protection layer has been derived.

Design of an integrated polarization band-pass filter

In this study, an integrated polarization band-pass filter was designed; it consists of a bilayer nanowire-grid polarizer and a multilayer dielectric band-pass filter. The grating parameters were optimized by rigorous coupled-wave analysis theory and analyzed by effective medium theory. Transverse magnetic transmission higher than 81% and extinction ratio higher than 1000 were obtained at 400–500 nm, and extremely low transmission in the other spectrum was also realized.

Light-emitting diode based shifted-excitation Raman difference spectroscopy (LED-SERDS)

Fluorescence interference is a common problem in Raman spectroscopy. A low-cost solution using shifted-excitation Raman difference spectroscopy (SERDS) with a light-emitting diode (LED) is presented. A conventional dielectric bandpass filter is employed to narrow the spectral bandwidth of the LED radiation and to stabilize its wavelength. Moreover, angle-tuning of the filter allows the wavelength to be controlled and shifted in order to record SERDS spectra.

K-PCS와 W-CDMA 듀얼밴드용 유전체 듀플렉서와 밴드패스 필터의 설계 및 제작

¹ Department of Electrical. Information and Communication Engineering, Wonkwang University, Iksan 570-749, Korea² Department of Electronics, Kwangwoon University, Seoul 139-701, Korea³ Department of Chemistry, Chonbuk University, Jeounju 561-756, Korea⁴RD Revised November 5, 2012; Accepted November 7, 2012)Abstract: The K-PCS and W-CDMA dual band dielectric duplexer and bandpass filters have been designed and fabricated. The dual band duplexer consists of the separate monoblock K-PCS and W-CDMA duplexers using common antenna port. The coupling capacitance and I/O impedance matching have been designed to minimize the cross interference between the bands. Isolations of crosspoint between Tx and Rx in K-PCS and W-CDMA dualband were about 47 dB and 100 dB, respectively. On the other hand, isolations of Tx and Rx in K-PCS and W-CDMA were about 66 dB and 65 dB, respectively. The difference between 47 dB and 100 dB originated from the different center frequencies in Tx and Rx of K-PCS and W-CDMA bands. The coupling capacitance of the bandwidth, I/O capacitance of I/O matching and impedance matching, and various capacitances were important role to fabricate the dielectric duplexer and bandpass filters.Keywords: K-PCS, W-CDMA, Isolation, Capacitance

Design of Pass Band Filter in Hybrid Architecture Planar/Non-Radiative Dielectric Waveguide Integration Technology

Problem statement: The expansion of RF, microwave and millimeter devices has revolutionized today's ommunication and sensor syst ems. Low-cost, high-performance and mass producible millimeter wave technologies are vital f or commercial broadband systems. Challenging issues are commonly faced in the design of low-loss integrated circuits for example high-Q band pass filter, which the planar technique is fundamentally limited in performance. Approach: In this study, we present a design of a nonradiativ e dielectric waveguide band pass filter based on hybrid architecture of micro strip line and non-radiative dielectric waveguide. Results: The simulation with High Frequency Structure Simulator (HFSS) three dimensional analyses is presented. Conclusion: The non radiative dielectric resolves most of the d rawbacks of dielectric waveguide in connection with the radiati on loss.

Space-qualified optical thin films by ion-beam-assisted deposition

Optical interference coatings designed for use in a space-grade multispectral assembly in a complementary metal-oxide‐semiconductor sensor were deposited on glass by ion-beam-assisted deposition for a Cassegrain-type space-based remote-sensing platform. The patterned multispectral assembly containing blue, green, red, near infrared, and panchromatic multilayer high/low alternated dielectric band-pass filter arrays in a single chip was fabricated by a mechanical mask and the photolithography process. The corresponding properties of the films were investigated by in situ optical monitoring and spectrometry. It was found that the optical properties were significantly improved by employing ion-beam-assisted deposition. The average transmittances were above 88% for the multispectral assembly, with a rejection transmittance of less than 1% in the spectral range 350–1100nm. To estimate the optical stability of optical coatings for aerospace applications, a space environment assuming a satellite orbiting the Earth at an altitude of near 800km was simulated by a Co60 gamma (γ) radiation test.

Effect of the Width of the NRD Waveguide on the S Parameter of a Pass Band Filter

In this paper, we present a design of a non-radiative dielectric waveguide band pass filter based on hybrid architecture of micro-strip line and non-radiative dielectric waveguide. The simulation with high frequency structure simulator (HFSS) three dimensional analyses are presented, also the influence of the feeding transitions for circuit design is studied. The aim of this work was to study the influence of the width of the NRD waveguide to scattering parameters.

Magnetic field tunable 18–36 GHz dielectric bandpass filter

Microstripline bandpass filters based on dielectric resonance in polycrystalline nickel ferrite have been designed and characterised for operation at discrete frequencies over 18–36 GHz. The filters have insertion loss of 2–5 dB and could be tuned by 0.5–1.3 GHz with a nominal magnetic field.

너치와 아이솔레이션을 활용한 CDMA와 W-CDMA 듀얼밴드용 유전체 듀플렉셔와 밴드패스 필터의 설계 및 제작

Using the notch and isolation, we investigated the insertion loss and isolation characterics of the fabricated dielectric duplexers and bandpass filters for CDMA and W-CDMA dualband. Insertion loss(Tx band) and isolation(between Tx and Rx) of duplxer were about -2.1708dB and 45dB at CDMA band, respectively. Also, in the case of W-CDMA, the insertion loss(Tx band) and isolation(between Tx and Rx) showed about -2.6946 and 100dB, respectively. Summering the aboved results, fabricated the dielectric duplexers and bandpass filters will be contributed the increase of atttenuation and the decrease of interference at CDMA and W-CDMA dualband.

고출력 특성을 고려한 능동 가변 대역 통과 여파기 설계

본 논문에서, 부성 저항 특성을 갖는 능동 커패시턴스 회로를 이용한 고출력 능동 가변 대역 통과 여파기는 동축형 유전체 공진기와 버랙터 다이오드를 사용하여 설계하였으며, 셀룰러 TX, RX 대역을 모두 가변할 수 있도록 설계하였다. 능동 커패시턴스 회로의 직렬 피드백 구조는 가변 대역 통과 여파기의 버랙터 다이오드로부터 생기는 손실을 보상함과 동시에 고출력 특성을 갖도록 하기 위해 <TEX>$P_{1dB}$</TEX>가 32 dBm인 GaAs HFET을 사용하였다. 버랙터 다이오드는 고선형 특성을 갖도록 하기 위해 back-to-back 구조를 사용하였다. 제작된 2단 능동 가변 대역 통과 여파기는 셀룰러 대역인 800 MHz에서 900 MHz를 가변하며, 각각 25 MHz 대역폭으로 TX 대역 836 MHz에서 0.48 dB 삽입 손실 특성을 나타냈으며, RX 대역 881.5 MHz에서 0.39 dB 삽입 손실 특성을 나타내었다. <TEX>$P_{1dB}$</TEX>특성은 TX 및 RX 대역에서 각각 19.5 dBm과 23 dBm을 얻었다. In this paper, a high power active tunable bandpass filter made of dielectric resonators and varactor diodes is designed using the active capacitance circuit generating negative resistance for tuning cellular TX, RX band. An active capacitance circuit's series feedback circuit using GaAs HFET whose <TEX>$P_{1dB}$</TEX> is 32 dBm is used for compensating the losses from the varactor diodes of the tunable bandpass filter. The tuning elements, the varactor diodes are used as the back-to-back configuration to achieve the high power performance, The designed active capacitance circuit improves the insertion loss characteristics. The designed 2-stage active tunable dielectric bandpass filter at cellular band can cover from 800 MHz to 900 MHz. The insertion losses at 836 MHz and 881.5 MHz with 25 MHz bandwidth are 0.48 dB and 0.39 dB, respectively. The <TEX>$P_{1dB}$</TEX> of the designed bandpass filter at TX and RX band are measured as 19.5 dBm and 23 dBm, respectively.

Enhancement of laser radiation coupled into turbid media by using a unidirectional mirror

This article analyzes a simple method for the enhancement of laser radiation coupled into deep layers of turbid samples. This is accomplished by using a multilayer dielectric bandpass filter that acts as a unidirectional mirror and reflects photons re-emerging from the sample back into it. The research establishes a theoretical framework, and a very basic feasibility study is performed. In this study, laser intensity, delivered through a 14 mm slab of tissue, and a 3.9 mm pharmaceutical tablet were enhanced by factors of 1.6 and 3.8, respectively. Potential applications include photothermal and photodynamic cancer therapies of subsurface tissue, deep optical spectroscopy and imaging of biological tissue and powders, as well as thermal and optical subsurface treatment of powder materials, colloids, and catalysts.