High Dielectric Constant Substrate Research Articles

Duplexer designed on the basis of microstrip filters using high dielectric constant substrates

A microstrip duplexer for a modification of a PCS communication system operating at frequencies of 1.84–1.87 and 1.75–1.78 GHz is described. The duplexer containing microstrip bandpass filters on high dielectric constant substrates (ɛr = 92) are compared with duplexers manufactured on microwave ceramic materials with high values of ɛr. The microstrip bandpass filters use stepped-impedance resonators placed one near another with a gap of 0.1–0.2 mm. It is shown that the microstrip duplexer has slightly lower insertion loss and occupies smaller volume than a duplexer using coaxial dielectric resonators having a rectangular cross section of 3 × 3 mm and ɛr = 92.

NOVEL CAPACITIVE GAP-COUPLED BANDPASS FILTER USING NON-UNIFORM ARBITRARY IMAGE IMPEDANCE

This paper introduces a new design technique for a capacitive gap-coupled bandpass fllter (BPF) using non-uniform arbitrary image impedances. Based on the proposed BPF equivalent circuit model, the fllter's design equations are derived, and they are validated from comparisons of the calculated and simulated results. For this theoretical veriflcation, the BPF using non-uniform arbitrary image impedances is designed using the speciflcations of: center frequency (fc) = 5:8GHz, fractional bandwidth (FBW) = 3:5%, and fllter stage (N) = 3. The calculated and simulated results of the designed fllter show good agreement. The BPF using the proposed design method could provide an advantage that one can arbitrarily determine two difierent image impedances, which ultimately afiects the BPF's coupling gaps and line widths. This could result in suitable fllter dimensions, i.e., gaps and line width, for a conventional low resolution photolithography fabrication although a low or high dielectric constant substrate is used for the design.

Thermal tunability in terahertz metamaterials fabricated on strontium titanate single-crystal substrates

We report an experimental demonstration of thermal tuning of resonance frequency in a planar terahertz metamaterial consisting of a gold split-ring resonator array fabricated on a bulk single-crystal strontium titanate (SrTiO₃) substrate. Cooling the metamaterial starting from 409 K down to 150 K causes about a 43% shift in resonance frequency, and there is very little variation in resonance strength. The resonance shift is due to the temperature-dependent dielectric constant of the strontium titanate. The experiment opens up avenues for designing tunable terahertz devices by exploiting the temperature-sensitive characteristic of high dielectric constant substrates and complex metal oxide materials.

Compact Coplanar Waveguide Spiral Antenna With Circular Polarization for Wideband Applications

This letter presents a compact, uniplanar, circularly polarized, coplanar waveguide (CPW) spiral antenna for wideband applications. The antenna is directly fed by a 50-Ω CPW from the outside edge of the spiral, thus a balun for matching is not required. This feed provides the capability to have an entire uniplanar array of spirals. It is found that a thick substrate of high dielectric constant absorbs most of the radiated power and results in a unidirectional radiation pattern, which is desirable in many applications. Therefore, this antenna structure is fabricated on a substrate of high dielectric constant, resulting in miniaturization and capability for integrated system applications. It is experimentally verified that the proposed spiral antenna has stable radiation pattern, and its axial ratio is less than 3 dB over the frequency range of 11.4-17.5 GHz.

Embedded Dual band Cylindrical Dielectric Resonator Antenna

A compact dual band antenna made of high dielectric constant substrate is studied. Embedding a higher dielectric cylindrical inside the substrate host cylindrical enhances the dual band behaviour. The first part displays the characteristics of single CRDA as return loss, bandwidth and radiation pattern, then, the second part describes the aim of using an antenna, composed by the arrangement of two cylindrical resonators in which the smallest is inserted in the largest, to lead dual-frequency behaviour, and achieve a dual-band antenna. The proposed antennas are investigated using Finite Element Method (FEM), the impedance matching dual band definition and covers the Ultra High Frequency band (UHF).

Develop CPW‐FED monopole broadband implantable antennas on the high dielectric constant ceramic substrates

AbstractA compact broadband planar monopole antenna fed by coplanar waveguide is developed and screen‐printed on the high dielectric constant microwave dielectric ceramic substrate for the applications of implanted biotelemetry. Biocompatible ceramic materials are selected for substrate (MgTa1.5Nb0.5O6, εr = 28) and superstrate (Al2O3, εr = 9.8). Additionally, for protecting from the tissue erosion, the metal parts (the body of the implanted antenna) are screen printed on a MgTa1.5Nb0.5O6 ceramic substrate and covered by a Al2O3 ceramic superstrate. Because the inductive loading effect generated by the rectangular type meander and the use of high dielectric constant ceramics, both size miniaturization and bandwidth enhancement can be achieved. The measured S11 of the proposed antenna in lossy emulated tissue is −43 dB, and the bandwidth of this proposed antenna can be improved to 100 MHz (351–461 MHz), which it is wide enough for the applications of modern MICS band (402–405 MHz) and ISM band (433–435 MHz). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2136–2139, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25376

Develop compact dual‐band bandpass filters on the aluminum oxide

AbstractFor the purpose of minimizing the dual‐band bandpass filters (2.4 and 5.7 GHz), two stepped impedance resonator structures are modified and involved in a pair of distorted coupled lines to form a compact structure.And because the designed filter is printed on the high quality factor and dielectric constant aluminum oxide ceramic substrate by the screen‐printing technique, the characteristics of the filters could be improved and the size of the filters could be minimized to only 22.2 × 12 mm2. Furthermore, the modified SIR structure can be used to tune the second resonant frequency (harmonic) for the applications of dual bands, and the modified coupled line structures can be used to excite additional transmission zeros and adjust its locations, which can improve the characteristics of the filters effectively. In this article, the optimum measured insertion loss and bandwidth for 2.4 GHz are −0.98 dB and 11.1%, respectively, and for 5.7 GHz are −1.05 dB and 10.1%, respectively. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1091–1094, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25126

A Modified .LAMBDA.0/4 Short-Circuited Stub Bandpass Filter for UWB Applications Utilizing LTCC Technology

In this paper, we utilize low temperature co-fired ceramic technology (LTCC) to realize a modified short-circuited stub bandpass filter suitable for ultra-wideband (UWB) applications. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate (er=40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter is fabricated and measurement results show that it has an insertion loss less than 1.0dB and return loss better than 10dB in the pass bands. A bandwidth ratio of 109.49% has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are 4×8×0.57mm3.

Miniature Antenna Using Printed Coupled Lines Emulating Degenerate Band Edge Crystals

A miniature printed antenna design that exploits higher-order dispersion behavior in degenerate band edge (DBE) crystals is proposed. First, the unit cell of a DBE crystal is emulated using a simple combination of uncoupled and coupled microstrip (MS) line sections printed on a low loss dielectric substrate. Subsequently, a resonant antenna is formed by cascading two such MS-DBE unit cells in a circularly periodic fashion. The first part of the paper is devoted to the antenna/array design and characterization using a low contrast dielectric substrate (Rogers Duroid, isinr = 2.2). Next, fabrication and design verification using a high dielectric constant substrate (alumina: Al2O3, isinr = 9.6) is given. The manufactured antenna was measured to have a broadside gain of 4.5 dB at 1.48 GHz with 3.0% bandwidth. For this gain and bandwidth, we demonstrate that the proposed MS-DBE antenna has a lambda0/9 times lambda0/9 footprint and is among the smallest in the literature.

저특성 임피던스의 λ0/4 단락 스터브 기술을 이용한 WLAN 저지 대역을 가지는 UWB BPF

본 논문에서는 기존의 <TEX>$\lambda_0$</TEX>/4 단락 스터브 대역 통과 필터의 특성을 개선하여 LTCC(Low Temperature Co-fired Ceramic)을 이용하여 UWB(Ultra Wideband) 응용에 적합한 필터 기술을 소개한다. 높은 유전 상수의 기판(<TEX>$\varepsilon_r$</TEX> = 40)상에 기존의<TEX>$\lambda_0$</TEX>/4의 단락 스터브 대역 통과 필터 기술을 적용하기 위하여 기존의 필터와는 다르게 낮은 특성 임피던스 선로를 이용하여 결과적으로 스터브의 수를 다섯 개에서 두 개로 감소시켰다. 또한, 3개의 단락 결합 선로를 이용해서 5.15 GHz에서 5.825 GHz의 주파수 범위에서 WLAN(Wireless Local Area Network) 저지 대역을 특성 내에 삽입하였다. 본 필터는 통과 대역에서 1 dB 미만의 삽입 손실과 10 dB 이상의 반사 손실을 갖는 것으로 측정되었고, 109.49 %의 대역폭 율이 달성되었다. 측정 결과는 시뮬레이션 결과와 잘 일치한다. 필터의 크기는 <TEX>$4{\times}8{\times}0.57\;mm^3$</TEX>이다. In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate(<TEX>$\varepsilon_r$</TEX> = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are <TEX>$4{\times}8{\times}0.57\;mm^3$</TEX>.

Triple‐band parallel coupled microstrip bandpass filter with dual coupled length input/output

AbstractA three‐order triple‐band bandpass filter is proposed to operate at 1.8/3.5/5.2 GHz for DCS, WIMAX, and WLAN applications. Three 1/2λ open‐loop resonators and two novel modified input/output structures parallel coupled are used as the bases. The cascaded resonators are designed for wide bandwidth and high out‐of‐band rejection. The modified input/output structure is used to tune the suppression/improvement of each spurious resonance. The filter is printed on Al2O3 ceramic substrate with 0.635 mm in thickness and has the relative dielectric constant 9.4. Because of the high dielectric constant substrate and novel feed in/out structure, the proposed filter with optimized parameters exhibits low insertion loss, high out‐of‐band rejection, wide bandwidth, and simple structure. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 995–997, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24257

Wideband microstrip antennas with sandwich substrate

A broadband microstrip antenna with low–high–low (sandwich) dielectric constant substrate combination using a microstrip line-via feed is presented for ultra-wideband applications. The proposed antenna consists of three dielectric substrates; low dielectric constant substrates that contain the microstrip feed line as well as parasitic patches and a high dielectric constant substrate that contains the driven patch. To achieve a large impedance bandwidth, parasitic patches and microstrip line-via combination feed to the driven patch in the multilayered microstrip antenna are used. The proposed antenna designed, fabricated and measured on the sandwich substrate. The antenna has measured 10 dB return loss bandwidth of 46.9% and directive gain >5.2 dBi at boresight across the impedance bandwidth. The total height of antenna is 5.77 mm or 0.077λo at 4 GHz.

High-frequency microstrip cross resonators for circular polarization electron paramagnetic resonance spectroscopy

In this article we discuss the design and implementation of a novel microstrip resonator which allows absolute control of the microwaves polarization degree for frequencies up to 30 GHz. The sensor is composed of two half-wavelength microstrip line resonators, designed to match the 50 Omega impedance of the lines on a high dielectric constant GaAs substrate. The line resonators cross each other perpendicularly through their centers, forming a cross. Microstrip feed lines are coupled through small gaps to three arms of the cross to connect the resonator to the excitation ports. The control of the relative magnitude and phase between the two microwave stimuli at the input ports of each line allows for tuning the degree and type of polarization of the microwave excitation at the center of the cross resonator. The third (output) port is used to measure the transmitted signal, which is crucial to work at low temperatures, where reflections along lengthy coaxial lines mask the signal reflected by the resonator. Electron paramagnetic resonance spectra recorded at low temperature in an S=5/2 molecular magnet system show that 82% fidelity circular polarization of the microwaves is achieved over the central area of the resonator.

Chessboard reflector for RCS reduction

It is shown that a simple interlaced pattern of doubly periodic square metal and dielectric patches constructed on a high dielectric constant substrate can redirect electromagnetic energy which is normally incident onto the surface away from boresight, thereby giving a means for RCS control. Between 15 and 30 dB of incident signal reduction over a 1–2 GHz bandwidth centred on 18.45 GHz is available by the method reported when a standard thickness microwave PCB material is used.

Substrate Integrated Image Guide Array Antenna for the Upper Millimeter-Wave Spectrum

A compact linear array antenna fed by substrate integrated image guide (SIIG) at 94 GHz is presented. The SIIG is a low-loss dielectric waveguide which is synthesized directly on a high dielectric constant substrate or semiconductor wafer. Such a low-cost approach of integration allows for the development of directive low profile antennas for future commercial millimeter-wave products. Special attention was directed towards the radiation elements that are fabricated in printed circuit technique on top of the SIIG. Their novel design provides a wide tuning range for the radiation coefficient and excellent linear polarization purity. In addition, an optimized reflection compensation technique effectively reduces the overall return loss and permits frequency scanning through broadside direction without suffering from a stop band due to distributed Bragg reflection. Published theory concerning the scan range of this class of frequency-scannable array antennas is extended in this work. Detailed design guidelines are given along with simulation and measurement results of a prototype. The 2 cm long implementation produced a fan beam with 11 dB gain.

A miniaturized bandpass filter fabricated on high dielectric constant ceramic substrates

AbstractA four‐pole open‐loop resonator bandpass filter fabricated on high dielectric constant (Zn0.9Mg0.1)TiO3 ceramic substrates is presented. The full‐wave simulator IE3D is utilized to calculate the coupling coefficients of each basic coupling structure and simulate S‐parameters of the designed bandpass filters. The center frequency of designed bandpass filter is fo = 2.45 GHz and the fractional bandwidth is 4%. The center frequency of the fabricated bandpass filter is at 2.47 GHz and the fractional bandwidth is 5%. The measured insertion loss and return loss of the filter is −3.68 and −14.92 dB, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2087–2090, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22698

Compact broadband coplanar waveguide-fed curved quasi-Yagi antenna

A novel uniplanar coplanar waveguide-fed quasi-Yagi antenna is presented. The originality of this design is because of its feed selection and its elliptical structure and in doing so achieving a wide bandwidth and compact size. An X-band prototype is developed and measures a bandwidth of 40%, with 3.2 dBi gain and 11 dB front-to-back ratio measured at 10 GHz. The antenna is realised on a high dielectric constant substrate and is compatible with monolithic microwave integrated circuits and solid-state devices.

Wideband microstrip-fed tapered slot antennas and phased array

Two wideband tapered slot antennas are designed, fabricated, and tested. The first antenna, which is fabricated on a high dielectric constant substrate (ϵr = 10.2), shows a measured return loss of better than 10 dB from 1.6 to 12.4 GHz (7.7:1 bandwidth), and an antenna gain varying from 3.6 to 7.8 dBi. The second antenna is built on a low dielectric constant substrate (ϵr = 2.2), and demonstrates return loss of better than 10 dB from 1.8 to 15.2 GHz (8.4:1 bandwidth). The second antenna also has improved antenna gain, from 5 to 15.6 dBi, and is used to build a wideband 1 × 4 H-plane phased array with a total gain of 9–17 dBi and a beam steering angle of ±15° from 3 to 12 GHz. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.

Simple Broadband Planar CPW-Fed Quasi-Yagi Antenna

In this letter, we present a novel coplanar waveguide fed quasi-Yagi antenna with broad bandwidth. The uniqueness of this design is due to its simple feed selection and despite this, its achievable bandwidth. The 10 dB return loss bandwidth of the antenna is 44% covering X-band. The antenna is realized on a high dielectric constant substrate and is compatible with microstrip circuitry and active devices. The gain of the antenna is 7.4 dBi, the front-to-back ratio is 15 dB and the nominal efficiency of the radiator is 95%.

Low profile wideband embedded dielectric resonator

A dielectric resonator antenna (DRA) made of high dielectric constant substrate is studied. Embedding a higher dielectric disk inside the substrate disk enhances the bandwidth. A narrow slot excites the DRA. Embedded DRAs of different shapes are considered for wideband applications. An eye-shaped DRA made with a circular dielectric resonator disk embedded in an elliptical-shaped ‘host’ DRA is found to have an impedance bandwidth of 28% with stable broadside patterns.