Broadband Via-Free Microstrip Balun Using Metamaterial Transmission Lines

A novel metamaterial broadband microstrip balun design is proposed. The broadband balun consists of a pair of identical metamaterial transmission lines. In the odd mode, a virtual ground is formed between the symmetric plane. The odd mode is allowed while the even mode is rejected. No vias are required to realize the shunt inductors of the metamaterial lines, and no power divider is used. Baluns with good performance can be achieved. In this letter, two baluns are fabricated and measured. For the balun with seven units, the output amplitude difference is less than 0.7 dB, and the differential phase is 181deg plusmn 3deg from 1.6 to 3.6 GHz, while the input return loss is greater than 10 dB.     

A Broadband Quadrature Power Splitter Using Metamaterial Transmission Line

A broadband quadrature power splitter (QPS) is developed using the metamaterial transmission line (MM TL). It consists of a Wilkinson power divider and two phase-adjusting TLs, namely a MM TL and a microstrip (MS). The slope of the phase-response curve of the MM TL is synthesized to be the same as that of the MS along with the 90deg phase increment at two design frequencies. Hence, the broadband quadrature phase difference over the desired frequency range can be obtained. In this letter, the QPS is developed at the center frequency of 2 GHz. Over the frequency range of 1.1-3.5 GHz, an amplitude imbalance of less than 0.9 dB and a phase error of less than plusmn5deg have been experimentally demonstrated.     

Varactor-Loaded Complementary Split Ring Resonators (VLCSRR) and Their Application to Tunable Metamaterial Transmission Lines

In this letter, the varactor-loaded complementary split ring resonator (VLCSRR) is presented for the first time. This particle is the dual counterpart of the varactor-loaded split ring resonator (VLSRR), which was introduced previously by some of the authors. Thanks to the presence of the varactor diodes, the electrical characteristics of the particle can be electronically tuned. Thus, by loading a microstrip line with VLCSRRs, the structure exhibits a tunable rejection band which is attributed to the negative effective permittivity provided by the particle. It is also shown in this letter that by adding a gap to the structure, the rejection band is switched to a tunable pass band with left handed wave propagation. Due to the topology of the complementary split rings resonators, the insertion and polarization of the diode varactors is not straightforward. These aspects are discussed in the letter. A circuit model for the VLCSRR is proposed. From parameter extraction and comparison between simulation of the circuit model and experiment good agreement is obtained.     

Planar Transmission Lines

This paper derives formulas for the transmission properties--characteristic impedance and attenuation--in the principal mode of a transmission line consisting of one or two long strips of metal foil embedded in a dielectric material between two long metal strips considerably wider than the central ones. The width and spacing of the central strips is arbitrary, and it is also necessary to take account of their thickness in computing the attenuation. A graphical method is given for evaluating the characteristic impedance in general, and analytic approximations are given for a number of special cases. Finally the question of the leakage of power from between the outer strips is considered briefly.     

Coupled Transmission Lines

An analysis of coupling between a stripline and a rectangular waveguide is presented. Coupling is through small apertures in the form of a circular hole or a narrow rectangular slot. A closed form expression for the normalized field distribution in the stripline, required for the purpose of analysis, is also derived. The theoretical results show good agreement with the experimental results.     

含各向异性特异材料的一维光子晶体的传输特性

利用传输矩阵方法研究了含各向异性特异材料的一维光子晶体的电磁传输性质.结果表明,光子晶体具有全向的零平均折射率带隙.这种全向带隙几乎不受晶格尺度、波的极化方向和入射角的影响.当一缺陷引入到光子晶体中时,会有电磁缺陷模出现.零平均折射率带隙中的缺陷模与普通Bragg带隙中的缺陷模不同,几乎不受晶格尺度、波的极化方向和入射角的影响.这一性质将在全向反射镜或滤波器中具有潜在的应用价值.     

Periodically Loaded Transmission Lines

In this paper equations for the transmission parameters of a periodically loaded line are derived in closed form with no restriction on the size, type or number of discontinuities. The equations also take into consideration any attenuation that may exist on the line. Several plots of the input reflection coefficient are presented and compared with experimental results. The agreement is very good.     

Slit-Coupled Strip Transmission Lines

Two types of slit-coupled strip-line configuration are presented which are especially useful for the realization of multi-section components using printed-circuit techniques. The slit-coupled configurations described consist of a pair of strips oriented face to face and either parallel or perpendicular to the outer ground planes. Coupling is achieved through a longitudinal slit. Exact conformal mapping solutions of the even- and odd-mode characteristic impedances are arranged in the forms of the design equations for both parallel and perpendicular cases. In order to facilitate design, nomograms are presented for the parallel case which give the physical line dimensions in terms of the even- and odd-mode characteristic impedances. Furthermore, the exact design equations for both parallel and perpendicular broadside-coupled strip configurations, which are considered to be special cases of the slit-coupled configurations, are presented. Formulas for the terminating lines are also included. The proposed parallel-coupled strip transmission line configurations permit smooth variation of coupling and applications to a wide variety of circuit components.     

Dual Composite Right/Left-Handed (D-CRLH) Transmission Line Metamaterial

The novel concept of dual composite right/left-handed (D-CRLH) transmission line metamaterial is introduced. The D-CRLH is the "dual" of the conventional CRLH in the sense that it has a series parallel (instead of series) LC tank and a shunt series (instead of parallel) LC tank. This topological duality results in dual properties. The D-CRLH indeed exhibits its left-handed (LH) band at high frequencies and its right-handed (RH) band at low frequencies and is of stop-band nature, in opposition to the CRLH which is low-frequency-LH/high-frequency-RH and pass-band. The so-called balanced condition is still valid in the D-CRLH for broadband matching. However, phase origin is at dc and infinity instead, as at the LH-RH transition, and the gap between the RH and LH bands cannot be closed up in practical implementations. In contrast, the D-CRLH provides an unlimited LH bandwidth. This letter presents the homogeneous and LC-network transmission parameters and the fundamental dispersion/impedance properties of the D-CRLH     

Problems in Strip Transmission Lines

A review is given of characteristic-impedance formulas for shielded-strip transmission lines. From these formulas a set of approximate relationships for the attenuation and Q of a dielectric-filled shielded-strip transmission line is derived. The method makes the standard assumption that the current distribution is that of a lossless line and the surface resistivity that of an infinite-plane condutor. Although this method applies accurately to most other types of lines, in this case an error of the order of 10% is believed to occur due to the failure of the assumptions at the corners of the strip. However, the error is in a direction that makes the computed values conservative, and the accuracy should be sufficient for most practical purposes. The derivation of a correction term is now being attempted. In addition to the discussion of attenuation attention is given in this paper to the design considerations involved in a shielded-strip-line impedance meter, and to some preliminary data obtained with this device. Also the future topics for investigation under this research and development program are mentioned.     

Monolithic Capacitors as Transmission Lines

The results of network analyzer measurements of high-Q multilayer (monolithic) chip capacitors show that the devices have the characteristics of open-circuited transmission lines. Both standard sizes (MIL-CDR-14 and MIL-CDR-12), ranging in capacitance values from 4.7 to 1000 pF, were tested on microstrip lines. A simple model of a periodically loaded line provides a dispersion relation that accounts for the distribution of resonant frequencies. The orientation of the capacitor with respect to the microstrip affects the occurrence and nature of resonances. This phenomenon is shown to result from a distributed excitation source. The unfolding of the capacitor to produce the periodic line is shdwn to produce anomalies in the dissipation loss when skin depth and electrode thickness are comparable.     

本地宽带传输网络建设思路探讨

对本地中继传输网络的现状进行了分析，认为城域波分可以很好适配业务网络发展，维护方便，网络安全性和容量得到了大幅提升，保证了传输网络和业务网络的可持续发展。     

传输线在宽带匹配中的应用

提出了一种宽带匹配网络设计的新思路。文中以任意输入阻抗的匹配为分析模型,详细分析了传输线在宽带匹配中的各种应用,并从宏观角度定性分析了传输线在阻抗匹配中的应用原理。在此基础上分析设计了一副工作在30～88 MHz频段、电压驻波比小于3．0的实用单极子天线,其实测结果良好地满足了要求。     

Periodic Cylinder Arrays as Transmission Lines

Periodic structures of conducting cylinders have been used as radiators (Yagi antennas), and, more recently, as slow-wave lines in traveling-wave tubes and masers. In this report it is shown that a nonresonant structure may have interesting capabilities as an open surface-wave transmission line. By means of a relatively simple matching network, efficient excitation of a surface wave on the periodic line is obtained. Response is flat over a 20 per cent frequency range at X band for several combinations of cylinder lengths and spacings. Total insertion losses are less than 3 db and largely independent of length of transmission line. Conducting cylinders are embedded in styrofoam. The effects of bends and twists in the line have also been investigated. It is shown experimentally that a guided wave on this periodic structure can follow a circular path having 1.5/spl lambda/ radius of curvature with very little loss. The plane of polarization can be rotated 90/spl deg/ by inserting a short twisted section. By terminating the transmission line with short circuits at both ends, a discrete series of transmission maxima is observed. Since these resonant peaks of transmission are of high Q factor, the dispersion characteristic of the line is obtained with very good accuracy. This type of open transmission line may offer advantages over heavy-weight and bulky conventional waveguides for some specialized applications.     

Transmission Lines Loaded at Regular Intervals

By a mathematical analysis, the switching time of an incident wave is predicted for a terminated net in which equal, lumped capacitive loads are repeated a finite number of times at regular intervals. The analysis is valid even for the ease of only a few Ioads, for which the distributed load approximation is poor. An APL program has been developed to compute the delay; its use is demonstrated by an example. The results are extended to include complex loads.