Wavelength Transmission Line Research Articles

Protection Scheme Half Wavelength Transmission Trunk Using Conventional Relay

This paper presents the main results on the use of conventional protection hardware to protect a Half Wavelength Transmission Line, or shortly AC-Link, for possible occurrence of three-phase and single-phase fault during energization maneuver. Lines of these dimensions do not exist today, but in countries of continental size they could be an interesting alternative to HVDC transmission, since the AC-Link has less dependence on Power Electronics technology. The studies on performance and relay settings were implemented using the RTDS real-time simulator. It is important to note that the AC-Link protection for the energization maneuver can be performed with existing hardware on conventional relays.

메타 재질 구조 CRLH 전송선 기반 소형 이중 대역 비균등 전력분배기

본 논문에서는 새로운 소형 이중 대역 비균등 전력 분배기를 제안한다. 기존의 1:2 비균등 Wilkinson 전력 분배기에서 <TEX>${\lambda}$</TEX>/4 길이의 분기 선로 대신 CRLH 위상천이용 전송선을 사용하여 전체 구조의 물리적 크기를 줄인다. 메타 재질 구조의 비선형 분산 특성을 이용하여 비균등 분기선들이 <TEX>$f_1$</TEX>, <TEX>$f_2$</TEX>에서 각각 <TEX>$+90^{\circ}$</TEX>, <TEX>$-90^{\circ}$</TEX>의 위상이 나타나는 이중 대역 특성을 갖도록 설계한다. 설계 방법의 타당성 확인을 위해, 등가 모델, 3차원 모의실험의 성능과 함께 CRLH의 특성인 분산도가 제시된다. 모의실험 결과와 측정 결과를 비교하였으며, 제안 기법의 소형화 효과가 논의된다. In this paper, a new compact dual-band unequal power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson's power divider, we use composite right- and left-handed(CRLH) phase-shift lines and can reduce the physical length. With the non-linear dispersion of the meta-meterial, each branch in the proposed divider is designed to have <TEX>$+90^{\circ}$</TEX> and <TEX>$-90^{\circ}$</TEX> at <TEX>$f_1$</TEX> and <TEX>$f_2$</TEX> respectively. To validate the proposed method, the performances of the circuit and full-wave simulation results are shown with the CRLH dispersion curve. The measurement results are compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed.

군 위성통신 중계기용 대역통과 여파기 특성을 갖는 CRLH O-차 공진 기반 소형 전력분배기의 설계

In this paper, a new compact power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson`s power divider design method, we use our composite right- and left-handed(CRLH) TX-line zeroth order resonator(ZOR) bandpass filters of one twelfth wavelength and reduce the physical length of the power divider. Besides, the filters in the branches can secure the passband for power-division. To validate the proposed power divider, we take an L-band for millitary satellaite transponder as the test case and the performances of the circuit and full-wave simulation results with the CRLH properties of the structure are shown with the dispersion curve and E-field at the ZOR. The measurement is compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed

비접촉 마이크로웨이브 프루브 시스템의 I/Q Demodulator를 위한 MMIC Mixer의 설계

A MMIC (Monolithic Microwave Integrated Circuit) mixer chip using the Schottky diode of an GaAs p-HEMT process has been developed for the I/Q demodulator of non-contact near field microwave probing system. A single balanced mixer type is adopted to achieve simple structure of the I/Q demodulator. A quadrature hybrid coupler and a quarter wavelength transmission line for 180 degree hybrid are realized with lumped elements of MIM capacitor and spiral inductor to reduce the mixer chip size. According to the on-wafer measurement, this MMIC mixer covers RF and LO frequencies of 1650MHz to 2050MHz with flat conversion loss. The MMIC mixer with miniature size of 2.5mm×1.7mm demonstrates conversion loss below 12dB for both variations of RF and LO frequencies, LO-to-IF isolation above 43dB and RF-to-IF isolation above 23dB, respectively.

Analytical method for optimal design of RF dual-band rat-race couplers for arbitrary frequency ratios

This article presents an analytical method to design a hybrid structure dual-band rat-race coupler at microwave frequencies. The proposed structure uses six identical cells of which each is engineered to work as a quarter wavelength transmission line with proper characteristic impedance at two distinct frequencies having arbitrary frequency ratio. The performances of the π- and T-cells are studied to assess their ability to provide the required electrical parameters for dual-band operation. It is demonstrated that the single-section π-topology can only lead to a suboptimal design for a dual-band rat-race cell at two nonharmonic frequencies. In contrast, the proposed double-section π-cell structure allows achieving an optimal dual-band cell design. A dual-band rat-race coupler designed at 2.14 and 3.6 GHz has been simulated and fabricated in hybrid microstrip technology. Measurement results agree well with analytically based simulation results, which demonstrate the effectiveness of the proposed structure for dual-band operation. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 690–700, 2012. © 2012 Wiley Periodicals, Inc.

주기적으로 배치된 용량성 소자를 이용한 단파장 전송선로의 기본특성 연구와 MMIC용 초소형 수동소자개발에의 응용

In this study, a short-wavelength transmission line employing periodically arrayed capacitive devices (PACD) was studied for application to miniaturized on-chip passive component on monolithic microwave integrated circuit (MMIC). The transmission line employing PACD showed shorter wavelength and lower characteristic impedance than conventional microstrip transmission line. The wavelength transmission line employing PACD structure was 8% of the conventional microstrip transmission line on GaAs substrate. Using the theoretical analysis, basic characteristic of the transmission line employing PACD (e.g., loss, effective dielectric constant, effective propagation constant, bandwidth ) were also investigated in order to evaluate its suitability for application to a development of miniaturized passive on-chip components on MMIC. Above results indicate that the transmission line employing PACD is a promising candidate for a development of miniaturized passive components on MMIC. Key w ords: Transmission Line, PACD(periodically arrayed capacitive devices), MMIC(monolithic microwave integrated circuit)

A New Miniaturization and the &lt;i&gt;n&lt;/i&gt;th Harmonic Suppression of Wilkinson Power

In this article, a simple structure of the Wilkinson power divider which can suppress the nth harmonics of the Wilkinson power divider is proposed. By replacing the quarter wavelength transmission lines of the conventional Wilkinson power divider with the equivalent P-type transmission lines, a compact power divider which can suppress the nth harmonic is achieved. Design equations of proposed P-type line are achieved by ABCD matrices. To verify the design approach, the proposed power divider is designed, simulated (by ADS, CST Studio, and Sonnet simulators), and fabricated at 1 GHz to suppress the fifth harmonic. The proposed structure is 46% of the conventional Wilkinson power divider, while maintaining the characteristics of the conventional Wilkinson power divider at the fundamental frequency. The insertion losses at the fifth harmonic are larger than 35 dB. Furthermore, the second to seventh harmonic are suppressed by least 10dB. Here is an excellent agreement between simulated results and measured results.

Analysis of miniaturized 3 dB branch-line hybrid couplers using distributed MIM capacitors

This letter presents the trade-off between size reduction and electrical performance of miniaturized branch line couplers using distributed capacitors placed in the inner open area of the hybrid. Based on single, double, and triple II-section approximations of the quarter wavelength transmission lines of a conventional design with high impedance lines and shunt metal-insulator-metal (MIM) capacitors, size reduction as well as electrical performance are compared both in simulation and experimentally. The miniaturized triple-section hybrid achieves similar bandwidth performance as the conventional 3 dB branch line hybrid coupler, but with a 61.2% smaller footprint. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1553–1556, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25273

Novel approach to the design of unequal power divider with high‐dividing ratio

AbstractThis letter presents the design of an unequal Wilkinson power divider with a high‐dividing ratio. By proportionally reducing the impedances in both arms and employing T‐shaped structure to replace quarter wavelength transmission lines with very low characteristic impedances, the proposed circuit can be constructed by microstrip lines with reasonable characteristic impedances, and therefore is easy to be fabricated and has planar structure. Furthermore, the value of isolating resistor can be flexibly adjusted to an available one. To verify our proposed idea, a 4:1 microstrip unequal power divider operating at 1.9 GHz is fabricated and tested. The ratio of highest to lowest characteristic impedances is only 2.2:1 in this 4:1 unequal power divider, compared with the ratio of 4.5:1 in conventional divider. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1240–1243, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24337

An Unequal Wilkinson Power Divider for a Frequency and Its First Harmonic

This letter presents a Wilkinson power divider operating at a frequency and its first harmonic with unequal power divider ratio. To obtain the unequal property, four groups of 1/6 wavelength transmission lines with different characteristic impedances are needed to match all ports. Theoretically, closed-form equations for the design are derived based on transmission line theory. Experimental results have indicated that all the features of this novel power divider can be fulfilled at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and 2 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> simultaneously.

A 2.4 GHz Fully Integrated Cascode-Cascade CMOS Doherty Power Amplifier

This letter presents the first CMOS Doherty power amplifier (PA) fully integrated on chip. The "cascode-cascade" amplifier architecture is proposed to get rid of the bulky power splitter and facilitate the integration. The quarter wavelength transmission lines are replaced by the lumped component networks such that the whole amplifier circuit can be squeezed into the die size of 1.97 times 1.4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Fabricated in 0.18 mum CMOS technology, the 3.3 V PA achieves 12 dB power gain. The measured output power and power added efficiency (PAE) at P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> dB are more than 21 dBm and 14%, respectively. The PAE at 7 dB back-off from P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> dB is above 10% and the PAE degradation is less than 29%.

Compact Feed Circuit with Quarter Wavelength Transmission Line Matrix Controlling Beams in Three Directions Including Boresight

A compact feed circuit with a λ/4 transmission line matrix circuit for use in array antennas to control beams in three directions, including boresight, is presented. The feed circuit antenna is composed of five switches and λ/4 transmission lines, and the feeding matrix circuit yields phase differences of ±90° and 0°. The feed circuit can obtain a reliable output signal, as there is only a small degree of deviation of output signal with variations in the line width. The feed circuit is simulated, fabricated, and evaluated for ISM band, and the measured characteristics agree well with the results of the simulation. The size of feed circuit is 45 (H) × 48 (W) × 3 (T) mm.

Loudspeaker low profile quarter wavelength transmission line and enclosure and method

A speaker enclosure including a compact quarter wavelength transmission path in the shape of a closed spiral that expands radially outward from a centrally located loudspeaker mounting location. The height of the transmission path has a minimum height that is equal to the height of the basket of the desired speaker. The quarter wavelength transmission path spiral of the provides an aerodynamic path for air flow therein which reduces the turbulence of air flow to a minimum that in turn provides even resistance to the air flow within the transmission line (Exhale vs. Inhale).

A compact harmonic‐suppressed Wilkinson power divider using C‐SCMRC resonators

AbstractThis letter describes a compact Wilkinson power divider using compensated spiral compact microstrip resonant cell (C‐SCMRC) resonators for harmonic suppression and size reduction. The size length of quarter wavelength transmission line is only 0.14 λg because of the slow‐wave characteristic. Furthermore, the proposed power divider rejected the 2nd and 3rd harmonic signals using the stopband of C‐SCMRC resonators. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2382–2384, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21961

Design and Performance of an Electrically Small Slot Loop Antenna With a Miniaturized Superconducting Matching Circuit

In order to realize a small superconducting receiver, we designed an electrically small slot loop antenna with a miniaturized impedance matching circuit. The area of the slot loop antenna is 4 mm /spl times/ 4 mm on MgO substrate at a frequency of 2.4 GHz. By applying 2-pole bandpass filter technique, we propose a design theory of the miniaturized impedance matching circuit that consists of coplanar waveguide (CPW) quarter and half wavelength transmission lines of meandering geometry and the impedance inverting circuits (J inverters). By using electromagnetic field simulator, we realized the circuit which matches the small radiation resistance R/sub a/=0.776 /spl Omega/ of the electrically small slot loop antenna to the feeder impedance Z/sub 0/=50 /spl Omega/, and attained the normalized bandwidth of 3%. We also made a preliminary experiment on this miniaturized antenna using a YBCO thin film on MgO substrate.

A three‐phase constant‐current source using an immittance converter

AbstractThe term immittance converter refers to an impedance–admittance converter. The immittance converter has an input impedance that is proportional to the admittance of the load connected across output terminals. In this converter, the output current is proportional to the input voltage and the input current is proportional to the output voltage. Consequently, it converts a constant‐voltage source into a constant‐current source and a constant‐current source into a constant‐voltage source.It is well known that the quarter wavelength transmission line shows immittance conversion characteristics. However, it has a very long line length for the switching frequency, and is not suitable for power electronics applications. We thus proposed immittance converters that consist of lumped elements L, C and show improved immittance conversion characteristics at a resonant frequency.A three‐phase constant‐current source is proposed in this paper. It is possible to realize this by a simple circuit using an immittance converter. In this paper, circuit operation, characteristic equations, and results of simulation are described. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(4): 47–54, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20078

Radio frequency bias current scheme for dc superconducting quantum interference device

We have developed a radio frequency bias current scheme with reversal frequency up to 50 MHz for dc superconducting quantum interference devices (SQUIDs). The SQUID and the readout electronics, were connected via a quarter wavelength (/spl lambda//4) transmission line. This transmission line not only transported the SQUID signal, but also served as the resonant matching circuit. For a dc SQUID of inductance 115 pH (loop size 75/spl times/75 /spl mu/m/sup 2/), we measured a flux noise of 33 /spl mu//spl phi//sub 0///spl radic/Hz at 77 K in the flux locked loop configuration. The corner frequency of 1/f noise was less than 0.5 Hz.

A branch‐line eight‐port hybrid circuit

AbstractThis paper deals with a circuit in which a total of eight ports made of two sets of four ports are mutually separated and in which the input from one port is delivered to four ports of another set with equal amplitudes with a certain phase relationship. This circuit is called the eight‐port hybrid circuit and is an extension of the characteristics of a conventional (four‐port) 3‐dB hybrid to the case of eight ports. A circuit configuration is proposed by means of four branch‐line‐type 3‐dB hybrids.First, by taking advantage of the symmetry of the circuit, an analysis is carried out. the relationship to be satisfied by the characteristic admittances of each branch line is determined. the frequency characteristics of the scattering matrix elements are presented.Next, a design method for broadening the bandwidth is given for the matching circuits to be attached to each port and quarter wavelength transmission lines connecting each hybrid. A relative bandwidth of about 20 percent is realized. Also, the test circuit is measured and the validity of the design method is confirmed. the present circuit is advantageous in that the circuit configuration is possible on one side of the substrate by means of strip lines and all eight ports are directed outward so that connection with other circuits is simplified.

Generalized rat‐race circuit with an arbitrary power‐split ratio

AbstractA rat‐race circuit consists of four constituent transmission lines whose length at the center frequency is an odd multiple of one‐quarter wavelength. One of these four lines is designed to have a difference in length by an odd multiple of one‐half wavelength in comparison to the remaining three. Especially, the circuit made of three one‐quarter wavelength transmission lines and one three‐quarter wavelength line with a total length of 3/2 wavelengths has been used most widely as the basic circuit.In this paper, with a view to finding the general constitutive conditions for a rat‐race circuit with an arbitrary power‐split ratio, a uniaxially symmetric circuit made of transmission lines with an arbitrary length and an arbitrary characteristic impedance is treated and the relationship is found between the electrical lengths and the admittance values of each transmission line section determined by the matching condition and the power‐split ratio. It is found that a circuit design is fundamentally possible if the ring length is more than one‐half wavelength.It is shown that a power divider with an arbitrary power‐split ratio can be designed with a circuit longer than one wavelength and that there is flexibility in the choice of the admittance values and the lengths of each section for a given power‐split ratio if the ring length is constant. Further, from the practical viewpoint, the foregoing results are used for miniaturization of the circuit and for design of large differences of power division with appropriate admittance values. The theoretical results are validated by experiments.

Broadband branchline coupler for S band

The design of an S-band, broadband, microstrip 3 dB, 90 degrees branchline coupler is described and measured results for a prototype version are given. The design uses broadbanding stubs and three branches, with the central branch split into two of twice the characteristic impedance and separated by half wavelength transmission lines. This is a new technique to improve the bandwidth of which a theoretical account was given by Mayer (see ibid., vol.26, no.18, p.1477-8, 1990). Measured results for the prototype coupler show return loss greater than 17 dB and isolation greater than 16.5 dB, over a percentage bandwidth of 45%. >