High temperature superconducting components for microwave systems

Belohoubek, E.; Kalokitis, D.; Fathy, Aly E.; Denlinger, E.J.; Piqué, Alberto; Wu, X. D.; Green, S.M.; Venkatesan, T.

doi:10.1016/0964-1807(93)90305-l

Cited by 23 publications

(13 citation statements)

References 8 publications

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“…Square planar monopole antennas are simple in geometry and easy to construct from a single metal plate. However, among planar monopole antennas of various shapes, the square planar monopole antenna has the drawback of providing a relatively smaller impedance bandwidth [1,2]. In order to improve the impedance bandwidth of the square planar monopole antenna, several bandwidthenhancement techniques have been reported, such as the use of a double feed [2], a semi-circular base [3], a beveling technique [4], a shorting pin [5], and so on.…”

Section: Resultsmentioning

confidence: 99%

“…1), the maximum impedance bandwidth is achieved by adjusting the value of d (the optimal value of d is generally in the range of 2.5 to 3.0 mm for L varied from 25 to 55 mm, and the obtained impedance bandwidth is in the range of about 1-3 GHz, depending upon the size of the planar monopole [1]). By cutting two notches of proper dimensions (w ϫ h) at the monopole's two lower corners, it is found that a much enhanced impedance bandwidth can be achieved for the proposed antenna.…”

Section: Antenna Designmentioning

confidence: 99%

“…The design procedure is described in [9], starting with only the couplings for a quasi-elliptic filter and finding suitable gaps between the resonators, as with the 5% bandwidth filter. Using an electromagnetic simulator, the filter response was predicted; then errors were corrected and additional couplings k 1,3 and k 4,6 were inserted over a few design iterations. The final device is shown in Figure 5.…”

Section: Amentioning

confidence: 99%

“…Spiral microstrip filters were proposed by [1] in connection with superconducting materials. Since then, successful devices have been reported [2,3].…”

Section: Introductionmentioning

confidence: 99%

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Compact copper microstrip filters with spiral resonators

Huang

Yue

Gulati

2004

Micro & Optical Tech Letters

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[2,3]. When conventional straight microstrip is miniaturized by making it narrower, there is a disproportionate decrease in the volume occupied by the electromagnetic field [3] because this volume shrinks in two dimensions. For spirals, there is less reduction of active volume because the combined fields of several parallel turns extends further down into the substrate, so that simulation accuracy for a given cell size is improved, the effect of over-etch is alleviated, and conductor losses are not so badly affected [3]. In this paper, two copper filters are investigated to see if these advantages still apply for normal metal implementations over a range of bandwidths. In contrast to the superconducting filters, which use relatively new technology, this work demonstrates spirals in the other extreme of very basic fabrication. It turns out that, because typical copper spirals contain only about two to four turns, the improvement (compared with a straight narrow microstrip) is only moderate, but can still be useful since there are benefits in three separate areas. Nevertheless, the main advantage is probably the more compact shape. Parallel-coupled filters tend to be long and thin, thus leading to a large border, which is necessary to separate the device from other circuit elements. Also, the electric and magnetic fields decay faster with distance for a spiral.One other nonsuperconducting spiral filter has been reported [4], but it requires via technology and only a lower-order filter was presented. A spiral has also been used in an oscillator circuit [5], while a recent example of a spiral as a lumped element was presented in [6]. 5% BANDWIDTH FILTER DESIGNThe filter layout is shown in Figure 1. The first and last spirals, which are connected to the input and output, are coupling structures equivalent to the input and output coupling lines in a parallelline filter. They are quarter-wavelength resonators, and the centres of each spiral are open circuit and the outer end is connected to a relatively low impedance of 50⍀. The resonant behaviour does not have a significant effect on the passband shape due to the low Q-factor. The four spirals in between form the four half-wavelength resonators of a 4 th -order Chebyshev filter. The substrate is 3.18-mm-thick RT Duroid 5870 ( r ϭ 2.33, tan ␦ ϭ 0.0012); use of a higher dielectric constant would have resulted in an even more compact device. An arbitrary centre frequency of 947 MHz was chosen, while the bandwidth is 5% (at 0.5 dB below the maximum in the lossless approximation).The design procedure is similar to [3], using coupling coefficients k for a 4 th -order 0.5-dB ripple filter taken from [7]. First, an appropriate spiral size was found by trial and error using a commercial full-wave electromagnetic simulator. As a starting point, the unwound length of the resonator should be a half-wavelength, and the effective permittivity is taken to be the permittivity of the substrate, where most of the electric field resides. For ease of fabrication and to retain the possibi...

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Section: Resultsmentioning

confidence: 99%

Section: Antenna Designmentioning

confidence: 99%

Section: Amentioning

confidence: 99%

“…Spiral microstrip filters were proposed by [1] in connection with superconducting materials. Since then, successful devices have been reported [2,3].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Compact copper microstrip filters with spiral resonators

Huang

Yue

Gulati

2004

Micro & Optical Tech Letters

View full text Add to dashboard Cite

show abstract

“…Spiral filters with fractional bandwidths of 0.1% to 27% have been previously demonstrated [3][4][5]14], but the higher bandwidths required very narrow, 15 micrometer gaps and 20 micrometer line widths, too small for reliable fabrication because the superconducting films from some suppliers can have faults up to 50 micrometers. Other spiral or wide band superconducting filters have also been reported [1,7,9,13,15].…”

Section: Introductionmentioning

confidence: 97%

Superconducting filter for radio astronomy using interdigitated, capacitively loaded spirals

Bolli

Huang

2012

Exp Astron

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A matched pair of microstrip spiral superconducting filters with centre frequency 357.5 MHz and 29.4% bandwidth has been developed for radio astronomy. The high coupling coefficients required for the large bandwidth have been achieved through interdigitating the spirals to provide a large interaction length, and by adding loading capacitors on the inner ends of the resonators, together with previously reported features. A low-pass filter has been cascaded with each band-pass filter to mitigate spurious responses. Measurements show 0.09 dB loss, thought to arise mainly from sources outside the filter itself, plus 0.12 dB maximum ripple.

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Experimental results on a 38-GHz high-temperature superconducting microstrip antenna

Castel

Floc'H

Guilloux‐Viry

et al. 1996

Microw. Opt. Technol. Lett.

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We have designed and fabricated a superconducting microstrip antenna operating at 38 GHz after we patterned a YBa,Cu,O, thin film epitaxially grown on (100) MgO substrate by laser ablation. The experimental performance of this superconducting antenna was measured in a homemade vacuum setup and compared to a similar silver antenna. Measurements show eficiency improvement of the superconducting antenna oc'er the silver one ABSTRACT A transmission-line-mattix (TLM) node equiualent. the TLM-based jinite-difference-time-domain IFDTD) method, has been recently propo.red to allow the simulation of electromagnetic fields in a FDTD fashion. As a result, modeling and simulation techniques deidoped for the conrxntional FDTD scheme can be directly implemented into the TLM-based algorithm. In this article the nonlinear modeling scheme acconiplished with a Z transfom is adapted and implemented in the proposed TLM-based FDTD method, to simulate the electromagnetic behaL,iors in optical media with nonlinear polarization, such as Kerr and Raman effects. Numerical results are presented for one-dimensional calculation of propagation of femtosecond electromagneric solitons that retain the optical carriers. The results are in good agreemeni with those obtained from the conuentional FDTD simulation. In conclusion. thr TLM-based FDTD method is found fo be robust undfiexible in 2D and 3D modeling. 0 1996 John Wley & Sons, Inc.

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High temperature superconducting components for microwave systems

Cited by 23 publications

References 8 publications

Compact copper microstrip filters with spiral resonators

Compact copper microstrip filters with spiral resonators

Superconducting filter for radio astronomy using interdigitated, capacitively loaded spirals

Experimental results on a 38-GHz high-temperature superconducting microstrip antenna

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