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Microwave Theory and Techniques, IEEE Transactions on

Issue 9 • Date Sept 1987

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Displaying Results 1 - 18 of 18
  • [Front cover - Sep. 1987 [T-MTT]]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Patent abstracts

    Page(s): 875 - 879
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    These patent abstracts of recently issued patents of interest to microwave engineers are intended to provide the minimum information necessary for readers to detennine if they are interested in examining the patent in more detail. Complete copies of patents are available for a small fee by writing: U.S. Patent and Trademark Office, Box 9, Washington, DC, USA. View full abstract»

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  • [Advertisement]

    Page(s): 880
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    Freely Available from IEEE
  • [Back cover - Sep. 1987 [T-MTT]]

    Page(s): b1 - b2
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    Freely Available from IEEE
  • Complex Gyrator Circuit of an Evanescent-Mode E-Plane Junction Circulator Using H-Plane Turnstile Resonators

    Page(s): 797 - 806
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    The E-plane circulator is of considerable practical interest but its development has lagged somewhat compared to that of the more common H-plane device. The purpose of this paper is to experimentally investigate the eigenvalue problem and the complex gyrator circuit of an E-plane evanescent-mode junction loaded with one or two H-plane turnstile ferrite resonators symmetrically coupled by three standard rectangular waveguides. The condition for which the eigenvalues of the demagnetized junction are in antiphase has been met with the physical variables at hand, but the more important one for which they are also commensurate has not. A transformer coupled device using quarter-wave-long impedance sections at each port is also described. Its frequency coincides with the even solution of two coupled resonators. View full abstract»

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  • Sidelobe Suppression in Low and High Time-Bandwidth Products of Linear FM Pulse Compression Filters

    Page(s): 807 - 811
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    The peak sidelobe suppression of unweighed linear FM surface acoustic wave filters limits the dynamic range of pulse compression systems. Using a discrete inverse Fourier transform "sampling technique" and complex Fresnel integral algorithms, this paper extends previous results of other authors from a time-bandwidth product of 50 up to the high value of 720. In the present work, the weighting is applied in the frequency domain, employing an external Hamming weighting function. The output waveforms are determined for different sampling rates. The results show that a peak sidelobe suppression of -38 dB from the main Iobe is achieved for high time-bandwidth product (TB = 720) at a sampling rate of 512 with broadening in the main lobe, while it is -41 dB for a low time-bandwidth product of TB = 50. Also, the paper contains charts showing the sidelobe suppression of unweighed and Hamming externally weighted linear FM pulse compression filters at different values of time-bandwidth products TB (50,100,250,370,510,720) with different central frequencies, dispersion times, and bandwidths B. The skirt steepness, sidelobe ripple rejection, Gibbs ripples of the wave spectrum, reduction of the insertion loss, and suppression of Fresnel ripples are also compared. View full abstract»

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  • Cylindrical Substrate Microstrip Line Characterization

    Page(s): 843 - 849
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    In this article, quasi-static and dynamic solutions are derived for microstrip transmission lines on circularly symmetric cylindrical substrates. Novel numerical techniques have evolved which lead to very efficient algorithms. The model is applicable to substrates of arbitrary thickness and cylinder size. Furthermore, it has been checked against a variety of limiting cases, including microstrip on a flat substrate, and it has been found to provide results with excellent accuracy. The analytical extraction of the quasi-static behavior from the dynamic Green's function introduces considerable simplicity in developing the algorithm. View full abstract»

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  • Cryogenic Operation of a Monolithic Slow-Wave Variable Phase Shifter (Short Paper)

    Page(s): 868 - 871
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    A GaAs slow-wave variable phase shifter has been investigated at 4.2, 77, and 300 K ambient temperatures over the 2-18-GHz frequency range. Differential phase shift Delta Theta has been measured and presented as a set of curves parameterized in terms of temperature covering the entire frequency range. Analytical explanations are provided for the phase shift Theta and insertion loss L behavior as functions of temperature, frequency, and bias voltage. The Schottky microstrip line resistivity ratio at 77 K is found to vary between 4 and 6 over the frequency range studied, giving about a 5:1 reduction in resistivity (or a 2:1 reduction in L) by going to liquid nitrogen temperature. View full abstract»

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  • Bias-Tuned Injection-Locked Discriminators

    Page(s): 812 - 818
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    A new form of microwave FM discriminator using simultaneously the technique of injection synchronization and automatic bias tuning has been proposed. The present discriminator basically consists of an injection-synchronized Gunn oscillator and an arrangement for bias tuning of the oscillator in correspondence to a measure of the instantaneous phase/frequency error between the incoming signal and the Gunn oscillator output. A detailed analysis on the discriminator performance, which closely fits in with the experimental results, has been presented. The performance of the present discriminator is much better than that of the conventional one. View full abstract»

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  • Analysis and Design of Microslab Waveguide

    Page(s): 850 - 857
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    Microslab, a novel low-loss semiplanar waveguide, is studied to provide design charts for the propagation constant and characteristic impedance. A parallel-plate analysis is performed to provide design guide-lines based on frequency, conductor loss, and size. A mode-matching procedure is then used to build the design charts. Results are provided for Microslab implementation on GaAs substrates. View full abstract»

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  • Effective Impedance of a Load Filling a Circumferential Slot in a Coaxial Transmission Line (Short Paper)

    Page(s): 862 - 865
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    A terminal load uniformly filling a narrow slot placed in the outer conductor of a coaxial transmission line presents a certain effective impedance to TEM waves propagating in the line. The relationship between this value of impedance and the voltage-to-current ratio at this load is established. The two are not necessarily equal. A numerical example is considered. View full abstract»

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  • A New Constant-Resistance ASK Modulator Using Double-Sided MIC

    Page(s): 819 - 822
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    A new constant-resistance ASK modulator using double-sided MIC techniques is proposed. (The term "double-sided MIC" refers to a circuit that utilizes both substrate surfaces.) The circuit consists of two quarter-wavelength slotlines, two variable-resistance elements, and a slot-to-microstrip transition. A balanced circuit configuration is used to obtain a high ON/OFF ratio at high frequencies. The modulator does not require circulators or hybrid couplers for perfect matching. The conditions required for impedance matching are also calculated. The experimental results are obtained in the frequency range from 25.0 to 29.5 GHz. The minimum insertion loss obtained is 2.8 dB, and the ON/OFF ratio is greater than 40 dB. The return loss is kept above 12 dB in the frequency range. This new modulator should prove useful for various applications such as variable equalizers and variable attenuators. View full abstract»

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  • On the Relationship Between TLM and Finite-Difference Methods for Maxwell's Equations (Comments)

    Page(s): 872 - 873
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    In the above paper, Mr. Johns compares the finite-difference time-domain (FD-TD) and transmission-line matrix (TLM) methods and concludes that: In the three-dimensional TLM method operated in the above way, there are three field quantities available at each shunt and series node, This, for example, allows the boundary description for TLM to be twice as fine as for finite differences. In two dimensions, If boundaries are described only at nodes as in finite differences, the incident pulses need only be at alternate nodes at any instant. Thus, an average of two stores for link lines, not four, is required at each node. View full abstract»

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  • TM0n0 - and TMm10 - Mode Oversized Cylindrical Cavity Power Combiners

    Page(s): 835 - 842
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    TMm10 -mode power combining is treated in addition to conventional TM0n0-mode combining in a multiple-device oversized cylindrical cavity having a window output structure. Mode analysis gives the condition for stable power-combining operation in the desired mode. By experiments both on TM0n0 -mode combining (n = 2, 3, and 4) and on TMm10 -mode combining (m = 2 and 8), it is shown that almost perfect power combining in the TM210 mode can be achieved as in the TM020 mode and that the power combining efficiency decreases gradually with increasing n or m. A possible advantage of TMm10 -mode combining in an oversized cavity is suggested based on the experimental result that power combining in the TM810 mode gives higher efficiency than in the TM040 mode. View full abstract»

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  • Attenuation and Power-Handling Capability of T-Septum Waveguides

    Page(s): 858 - 861
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    In this paper, the attenuation characteristics and power-handling capabilities of single T-septum waveguides are presented.The analysis is based upon numerical solutions employing the Ritz- Galerkin technique [1]. The analysis was verified by applying it to the known results obtained for the ridged waveguide, which is treated as a special case of the T-septum guide. A good agreement has been achieved compared with the results from Hopfer [2]. It is found that the single T-septum guide can handle less power, but has lower attenuation than the single-ridged guide with identical gap parameters. Equations and charts are presented to facilitate the design of T-septum waveguides. View full abstract»

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  • Depth of Penetration of Fields from Rectangular Apertures Into Lossy Media (Short Paper)

    Page(s): 865 - 867
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    A widely used device for biomedical applications of microwave energy is the dielectric-loaded waveguide operating in the TE10 mode. We have calculated the (1/e) energy penetration depth from such antennas, modeled as rectangular apertures radiating into a lossy medium with dielectric properties resembling those of tissue. The results are presented in nondimensional form from which the characteristics of practical antennas can be estimated. Depending on the dielectric properties of the medium and the size of the aperture, the effective penetration depth can be limited by either the aperture size or the plane-wave penetration depth practical antennas fall between these two extremes. Experimental results confirm the calculations. View full abstract»

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  • Rigorous Analysis and Network Modeling of the Inset Dielectric Guide

    Page(s): 823 - 834
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    The inset dielectric guide (IDG) is an easy-to-fabticate alternative to image line and is also less sensitive to loss by radiation at discontinuities. This paper presents a rigorous variational analysis in space domain based on field and network considerations (transverse resonance diffraction). This approach yields an accurate transverse equivalent network for the fundamental mode suitable for evaluation by a desktop calculator. Theoretical and experimental results are in excellent agreement. View full abstract»

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  • Indefinite Integrals Useful in the Analysis of Cylindrical Dielectric Resonators (Letters)

    Page(s): 873 - 874
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    Little-known integrals are listed, useful for the evacuation of stored electric energy in cylindrical regions, such as often appear in the analysis of cylindrical dielectric resonators. View full abstract»

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Aims & Scope

The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

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