Artificial Dielectric Substrate Research Articles

Development of a slow-wave artificial dielectric substrate-based microstrip line in X band

This paper presents a slow-wave artificial dielectric substrate for planar microstrip device miniaturization. The proposed substrate supports the improvement of the permittivity of a given substrate, and in turn offers guided wavelength reduction, leading to obtaining size reduction using low cost printed circuit board (PCB) process. In this structure, two rows of metal vias are located on either side of a microstrip line (ML), which are connected to the ground plane of the substrate. In addition, a row of metal mushroom-shaped vias is placed and connected at the center of the line, which is inserted inside the dielectric media. This would lessen the effective distance between the microstrip line and the ground, and so, the capacitance per unit length is increased leading to obtaining a slow-wave substrate. The proposed structure is numerically investigated using full wave software for specified parameters and the microstrip line characteristics are compared with those of the conventional line. A prototype of the introduced line is implemented and its measured propagation features, including phase constant and effective permittivity, are reported. Results show a perfect agreement with those of simulation, which confirms that a 50.6% longitudinal size reduction is feasible.

Broadband non-resonant split ring resonator-based artificial high dielectric substrate

This paper presents a technique of using magnetic metamaterial as a broadband non-resonant artificial high dielectric substrate for achieving enhanced radiation performance in the microwave region. The selected metamaterial (MTM) is the basic single split-ring resonator (SRR) printed on a bare dielectric substrate of permittivity 3.8. When it is electrically excited by a plane wave, a high permittivity of 25 for the frequency range of 0.5–3.1 GHz is achieved. The application of the artificially made high dielectric substrate is validated with a 1.3 dBi gain enhancement of a broadband slot antenna with a single finite transmitter array of 5 × 4 high dielectric metamaterial substrate. The MTM-antenna composite is having an overall size of 60 × 48 × 21.6 mm3 when printed on a substrate of dielectric constant 3.8 and height 1.6 mm. The detailed study of MTM unit cell and the effect of MTM on antenna performance is thoroughly studied in simulation and validated with free space measurements.

Design of a Branch Line Coupler Using Double-Sided Artificial Dielectric Substrate Structure

Design of a Branch Line Coupler Using Double-Sided Artificial Dielectric Substrate Structure

Design of a Branch Line Hybrid Coupler Using Artificial Dielectric Substrate and Defected Ground Structures

가유전체 기판구조와 결함접지구조를 이용하여 가지선로 하이브리드 결합기를 소형화하여 설계한 결과에 대하여 기술한다. 가유전체 기판구조에서는 유효유전율과 단위 길이당 등가의 커패시턴스가 크게 증가한다. 결함접지구조는 기하학적 패턴 때문에 단위 길이당 등가의 인덕턴스가 증가하는 효과를 갖는다. 이 두 구조는 각각 단위 길이당 등가 회로 소자값들을 증가시키므로 상보적인 효과에 의하여 전송선로의 특성 임피던스를 크게 변화시키지 않으면서도 회로의 소자값들을 동시에 줄이는 효과를 갖는다. 본 논문에서는 적용예로 종래 구조보다 크기가 크게 줄어든 가지선로 하이브리드 커플러를 설계, 제작 및 측정한 결과를 제시한다. 가유전체 기판과 결함접지구조를 적용하여 설계된 회로는 가유전체만을 삽입했을 때와 결함접지구조만을 삽입했을 때에 비하여 각각 68%, 54%의 크기를 갖는다. 중심주파수에서 측정된 전력분배와 위상차는 각각 ?3.08dB, -3.87dB, 93°인데, 이는 가유전체 기판과 결함접지구조를 이용한 소형화 이후에도 성능상의 큰 열화가 없음을 보여준다.

가유전체 기판을 이용한 소형화된 링 하이브리드 커플러의 설계

본 논문에서는 가유전체 기판을 이용하여 소형화한 마이크로파 대역의 링 하이브리드 커플러 설계에 대하여 기술한다. 가유전체 기판은 다수의 비어홀을 제 2기판에 삽입하여 유효 커패시턴스를 크게 증가시킨 구조를 갖는다. 가유전체 기판의 유효유전율은 표준형 기판에 비하여 크게 증가하게 되는데, 이에 의하여 동일한 전기적 길이 대비 물리적 길이가 크게 감소하므로 마이크로파 전송선로를 소형화시킬 수 있다. 이런 원리를 마이크로파 무선회로 설계에 적용한 사례를 보이기 위하여 가유전체 기판을 이용하여 3GHz대 링 하이브리드 커플러를 설계하고 실제로 제작 및 측정한 결과를 제시한다. 설계된 소형화된 링 하이브리드 커플러는 표준형에 비하여 전기적 성능은 유사하면서도 65%의 크기를 가진다. 측정된 전력분배비는 각각 -3.05dB와 -3.135dB이며, 두 출력간의 위상차는 동위상일 때 3도, 역위상일 때 176도로 이상적인 값과 매우 유사하다. 이로써 가유전체 기판구조로 소형화된 링 하이브리드 커플러의 설계가 타당함을 보인다. This paper describes the design of a size-reduced ring hybrid coupler for microwave band using an artificial dielectric substrate(ADS). ADS structure adopts the second substrate on which has lots of the metalized via-holes. The effective capacitance and effective dielectric constant per unit length of ADS increases compared to the normal substrate due to the via-holes. This enables the physical length of microstrip transmission line to be reduced by adopting ADS instead of the normal substrate. In order to present an example of size-reduction of microwave wireless circuit by ADS, a size-reduced 3GHz ring hybrid coupler is designed, fabricated and measured in this work. The designed coupler has the smaller size from the normal one by 65% due to the ADS, while no critical degradation from ideal performances is observed. The measured power division ratio at two output ports are -3.05dB and -3.135dB, respectively. In addition, the phase differences are 3o for in-phase division and 176o for out of phase split. The measured performances are so similar to ideal ones, and prove the design of size-reduced ring hybrid coupler using ADS is successful.

결함접지구조와 가유전체 기판구조를 결합한 전송선로의 설계

본 논문에서는 결함접지구조와 가유전체 기판구조를 이용하여 새로운 초고주파 대역 전송선로 구조가 제안된다. 결함접지구조는 전송선로의 단위길이당 등가의 인덕턴스를 증가시켜 동일한 선폭일 때 전송선로의 특성 임피던스를 키우면서 선로의 길이를 줄여준다. 가유전체 기판구조는 전송선로의 단위길이당 등가의 커패시턴스를 증가시켜, 동일한 선폭일 때 전송선로의 특성 임피던스를 낮추면서 선로의 길이를 줄여준다. 따라서 결함접지구조와 가유전체 기판구조는 모두 전송선로의 길이를 줄이면서 선폭에 대해서는 상보적인 역할을 한다. 그러므로 두 구조가 결합되면 전송선로의 특성 임피던스는 크게 변하지 않은 채 길이만 더욱 줄일 수 있으므로, 초고주파 회로의 소형화에 크게 유리하다. 본 논문에서는 결함접지구조와 가유전체 기판구조를 모두 결합시킨 <TEX>$35{\sim}100{\Omega}$</TEX> 전송선로를 설계하고, 실제로 제작 및 측정하여 그 결과를 제시하는데, 특성 임피던스의 예측값과 측정값이 잘 일치함을 보인다. 동일한 전기적 길이에 대하여 제안한 전송선로는 Fig.준형 마이크로스트립 전송선로에 비하여 불과 55.4~76.9% 물리적 길이를 갖는다. In this work, a new high frequency transmission line structure combined with defected ground structure (DGS) and artificial dielectric substrate (ADS) structure is proposed. DGS patterns give add the additional inductance to transmission lines and results in the increased characteristic impedance for a given line width. To the contrary, ADS presents increased capacitance and reduced line impedance. So both play a role in reducing the length of transmission lines commonly, but in preserving the line impedance complementarily. This means that the length of transmission lines can be reduced furtherly by DGS and ADS without a critical change of line width compared to the cases when one of DGS and ADS is used only. As examples, <TEX>$35{\sim}100{\Omega}$</TEX> transmission lines having DGS and ADS are designed, fabricated, measured, and compared to the simulation results. A good agreement between the simulated and measured line impedances is presented. In addition, the physical lengths of the proposed transmission lines are only 55.4~76.9% of those of the normal microstrip lines for the same electrical lengths.

임의유전체 기판을 이용한 주파수 혼합기의 소형화

A size-reduced high frequency mixer designed by adopting artificial dielectric substrate is described in this work. The artificial dielectric substrate is composed by stacking the lower substrate in which a lot of metalized via-holes exist, and upper substrate on which microstrip lines are realized. The effective dielectric constant increases due to the inserted lots of via-holes, and this may be applied to size-reduction of high frequency circuits. In this work, in order to present an application example of size-reduction for active high frequency circuits using the artificial dielectric substrate, a 8GHz single gate mixer is miniaturized and measured. It is described that the basic circuit elements for mixers such as hybrid, low pass filter, and matching networks can be replaced by the artificial dielectric substrate for size-reduction. The final mixer has 55% of size compared to the normal one. The measured average conversion gain is around 3dB which is almost similar result as the normal circuit.

가유전체 기판을 이용한 비대칭 브랜치 라인 커플러의 설계

본 논문에서는 가유전체 기판구조를 이용한 비대칭 브랜치 라인 커플러의 설계에 대하여 기술한다. 가유전체 기판구조에서는 주기적으로 다수의 비어홀들이 삽입되므로 등가적으로 유효유전율과 유효투자율이 증가하여, 여기에 전송선로를 구현할 경우 표준형 선로에 비하여 동일한 전기적 길이일 때 물리적 길이와 선폭이 감소하게 된다. 이런 특성을 이용하여 초고주파 회로들을 소형화하여 설계할 수 있는데, 본 논문에서는 2GHz대에서 동작하는 3:1 비대칭 브랜치 라인 커플러를 소형화하여 설계하는 것에 대하여 기술한다. 설계된 커플러는 표준형 전송선로를 이용하여 설계한 회로에 비하여 동일한 성능을 가지면서 약 53.4%의 크기를 갖는다. 비대칭 전력 분배 비율이 시뮬레이션과 측정 데이터에서 잘 일치하고 있으며, 측정된 손실도 불과 0.2dB 이내로 매우 적다. In this paper, the design of asymmetric branch line couplers using artificial dielectric substrate (ADS) is described. The effective permittivity and permeability increase in ADS because of the lots of the inserted via-holes. So the physical length and width of transmission lines realized on ADS are reduced compared to the standard lines. This enables one to design size-reduced microwave circuits. As an instance in this work, an asymmetric branch line coupler with the ratio of 3:1 is designed at 2GHz. The designed coupler has a small size of 53.4% compared to the normal circuit while the same performances are preserved. A good agreement between the simulated and measured asymmetric power dividing ratio is shown. The measured loss is only less than 0.2dB, which is a very small value.

방향성결합기의 소형화를 위한 가유전체 기판구조의 응용

This paper describes the design of size-reduced directional coupler using the artificial dielectric substrate and its increased effective permittivity. Directional couplers are widely used in measuring RF power indirectly and coupling signal power. Artificial dielectric substrates have higher effective dielectric constant than standard dielectric substrate due to the lots of metalized via-holes, and the increased effective permittivity results in size-reduction of circuits. As a design example, 15dB directional couplers are designed on the standard substrate and artificial dielectric substrate and their size are compared. The size of the directional coupler using the artificial dielectric substrate is only 1/3 of that designed using the standard substrate, while the performances are preserved. In addition, the measured performances of the size-reduced coupler are well agreed with the simulated ones. The measured coupling coefficient, matching, and insertion loss at 2GHz are -14.62dB, -24.1dB, and -0.38dB, respectively.

Reflection-Type Artificial Dielectric Substrate Microstrip Dispersive Delay Line (DDL) for Analog Signal Processing

A reflection-type artificial dielectric substrate (ADS) microstrip dispersive delay line (DDL) for analog signal processing is presented. This DDL is realized by nonuniformly alternating conventional and ADS microstrip sections with a linearly increasing period (linear group delay or constant chirp) so that the different spectral components of a modulated signal incur different delays proportional to their frequency to be discriminated in time. Design guidelines are provided. The proposed DDL is demonstrated theoretically, numerically, and experimentally, and is fully characterized in terms of reflective level, bandwidth, group delay, and chirping coefficient for excitation at both ports. The DDL is then demonstrated in a frequency discriminator. Finally, it is compared with a stepped-impedance DDL and a sinusoidal-impedance DDL, and shown to exhibit superior symmetry along to smaller overall loss due to dramatically mitigated radiation, thereby leading to superior performances in various analog signal-processing systems such as impulse delay lines, real-time Fourier transformers, and compressive receivers.

Microstrip line on an artificial dielectric substrate

This letter presents a new version of an artificial dielectric substrate and a microstrip line built on top of this substrate. The substrate is fabricated as a two-dimensional array of metallic posts separated from the top conductor by a thin dielectric slab. This structure can show a very high effective permittivity and can therefore offer a substantial reduction in the dimensions of microwave circuit elements