A superconducting thin film filter of very high wide-band rejection

Yi, H. R.; Remillard, Stephen K.; Abdelmonem, A.

doi:10.1109/mwsym.2003.1210527

Cited by 12 publications

(6 citation statements)

References 4 publications

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“…From previous experience [7] and a plenty of published fullwave simulation and experimental data [13][14][15][16]25] using the same materials and EM software, it can be noted that the modeling and simulation results are expected to agree well with tests but with a relative deterioration into the IL, RL, and the F BW . This shall presumably due to extraneous factors that could not be accounted for in the simulations such as fabrication tolerance, coaxial to microstrip transition matching, cooling medium, contraction of circuits at low temperature, material quality and contact interfaces (e.g., metal/HTS).…”

Section: Experimental and Discussionmentioning

confidence: 99%

“…Further recent works show the importance of achieving ever narrower bandwidths and higher out-of-band rejection required in the wireless communications industry [13][14][15], and even in radio astronomy [16]. In one work [15], a HTS microstrip filter, but with lumped-element realization, has shown a possible F BW of 0.014% at a midband frequency of 700 MHz.…”

Section: Introductionmentioning

confidence: 99%

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Em Full-Wave Analysis and Testing of Novel Quasi-Elliptic Microstrip Filters for Ultra Narrowband Filter Design

Hejazi¹,

Scardelletti²,

Keuls³

et al. 2008

PIER

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Abstract-A new class of microstrip filter structures are designed, optimized, simulated and measured for ultra-narrowband performance essential to the wireless industry applications. More accurate model of the coupling coefficient is outlined and tested for narrowband filter design. Two sample filters are fabricated and measured to verify the simulations and prove the concept. The idea behind the new designs is based on minimizing the parasitic couplings within the resonators and the inter-resonator coupling of adjacent resonators. A reduction of the overall coupling coefficient is achieved even with less resonator separation which is a major issue for compactness of such filters. The best new designs showed a simulated fractional bandwidth (F BW ) of 0.05% and 0.02% with separations of S = 0.63 mm and S = 0.45 mm, respectively. The measured filters tend to have even narrower F BW than the simulated, though its insertion loss deteriorates, possibly due to mismatch at the interface with external circuitry and poor shielding effect of the test platform. The investigated 2-pole filters are accommodated on a compact area of a nearly 0.6 cm 2 . An improvement of tens of times of order in narrowband performance is achieved compared to reported similar configuration filters and materials. A sharp selectivity and quasi-elliptic response are also demonstrated with good agreement in both simulations and measurements. In all filters, however, the study shows that the narrower the F BW , the larger the insertion loss (IL) and the worse the return loss (RL). This is confirmed by measurements.

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Section: Experimental and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Em Full-Wave Analysis and Testing of Novel Quasi-Elliptic Microstrip Filters for Ultra Narrowband Filter Design

Hejazi¹,

Scardelletti²,

Keuls³

et al. 2008

PIER

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Section: High-performance Narrowband Hts Filtermentioning

confidence: 99%

“…Besides, it is not easy to achieve better return loss (such as, better than −20 dB) due to the complexity of tuning at low temperature and in vacuum. There are, to our knowledge, only a couple of reports in the literature of HTS filters with high-performance specification of return loss (< −20 dB) and/or out-of-band rejection (> 95 dB) [13][14][15].In this work, we present a 10-pole high-performance narrowband HTS filter with a cascaded quadruplet coupling structure. The filter has an excellent return loss (−22.5 dB in the passband) and a high out-of-band rejection (close to 100 dB in a wideband range).…”

mentioning

confidence: 99%

A high-performance narrowband high temperature superconducting filter

et al. 2010

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Recent development of a high-performance narrowband high-temperature superconducting (HTS) filter is presented. A 10-pole quasi-elliptic function response filter with two pairs of transmission zeros (for high selectivity), which has a center frequency of 2.185 GHz and a 3 dB bandwidth of 10 MHz (a fractional bandwidth of 0.45%), is introduced. The filter was fabricated on a 40 mm×16 mm×0.5 mm MgO wafer with double-sided YBCO films. The measured results show that the filter has 0.15 dB insertion loss at the center of the passband and a return loss better than −22.5 dB at a temperature of 67 K. Band edge steepness reaches over 28.3 dB/MHz at both the low and high frequency edges. The out-of-band rejection is over 78 dB at 8 MHz away from the center frequency and close to 100 dB in a wideband range. high-performance, narrowband, HTS, filterCitation: Cui B, Zhang X Q, Sun L, et al. A high-performance narrowband high temperature superconducting filter. Recently, superconducting devices have been developed steadily in China. Superconducting materials have been widely used in the development of kinds of devices, such as filters [1-4], single photon detector [5] and hot electron bolometer (HEB) mixer [6]. Among these, an important aspect is the development of high-performance narrowband microwave filters. Generally speaking, the insertion loss of a filter is inversely proportional to its fractional bandwidth (FBW), and thus it is difficult to realize narrowband filters (for example FBW<0.5%) using normal metals. The hightemperature superconducting (HTS) films have a thousand times smaller microwave surface resistance than normal metal films. Therefore they are suitable for use in fabricating such narrowband filters and many works on narrowband HTS filters have been reported since early 1990s [7][8][9][10][11][12].In most cases, to realize high selectivity, HTS filters are constructed by numbers of resonators which are arranged within a testing house. The compact size of HTS filters will introduce some unwanted parasitic couplings between nonadjacent resonators, which makes it hard to realize a high out-of-band rejection. Besides, it is not easy to achieve better return loss (such as, better than −20 dB) due to the complexity of tuning at low temperature and in vacuum. There are, to our knowledge, only a couple of reports in the literature of HTS filters with high-performance specification of return loss (< −20 dB) and/or out-of-band rejection (> 95 dB) [13][14][15].In this work, we present a 10-pole high-performance narrowband HTS filter with a cascaded quadruplet coupling structure. The filter has an excellent return loss (−22.5 dB in the passband) and a high out-of-band rejection (close to 100 dB in a wideband range). A double-folded resonator structure [16], which has been developed in our laboratory for a filter with a center frequency of 8 GHz, is used in our design to realize the high out-of-band rejection level. A novel asymmetrical cross coupling structure is introduced to implement the filter with two pairs of t...

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“…More recent works show the importance of achieving ever narrower bandwidths (up to 0.11%) and higher out-of-band rejection required in the wireless communications industry [13][14][15], and even in radio astronomy [16]. An HTS microstrip filter with lumped-element realization has been reported to achieve FBW of 0.014% at a midband frequency of 700 MHz [15].…”

mentioning

confidence: 99%

A new model to calculate the coupling coefficient for more accurate filter design and further development of narrowband-filter performance

Hejazi¹,

Jiang²

2005

Microw. Opt. Technol. Lett.

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between the ground lines of 156 m demonstrated similar improvement. The results from the 60-m-wide microstrip lines suggest that maintaining a constant line width so that the probe pad structure is indistinguishable from the transmission line, if possible, is best. This allows direct probing of the transmission line without introducing error during the removal of probe-pad parasitics or correction for microstrip-width variations.In either situation, it is then possible to implement the calibration-comparison method by inserting an impedance transformer to map the reference impedance of the measurement into the reference impedance Z 0 of the multiple, redundant line standards and the following the procedure given in [7][8][9]. Investigations continue to determine if following this approach results in a more accurate characteristic impedance determination.The author thanks Dr. Mark Gouker from MIT Lincoln Laboratory for fabricating the transmission-line structures and providing all of the scattering-parameter measurements. More recent works show the importance of achieving ever narrower bandwidths (up to 0.11%) and higher out-of-band rejection required in the wireless communications industry [13][14][15], and even in radio astronomy [16]. An HTS microstrip filter with lumped-element realization has been reported to achieve FBW of 0.014% at a midband frequency of 700 MHz [15]. A previous recent work [17], showed a possible FBW of up to 0.05% achieved at wireless frequencies using a new version of folded spiralmicrostrip geometry, where the current directions in all adjacent sections of a resonator are forced to be opposite to each other so as to minimize parasitic internal couplings and hence reduce the overall coupling coefficient. However, the design of planar ultranarrowband filters with FBW of less than 0.1% generally still face the following constraints: a very weak coupling with a reasonably smaller separation between resonators in order to maintain a small circuit size. The other challenge is to identify and control the required electric and magnetic nonadjacent cross-couplings in or- der to achieve a highly selective elliptic function response with transmission zeros near the passband. Also, it was found that the standard model used for extracting the coupling coefficient between two resonators or two degenerate modes (in dual-mode filters) can not be accurate when the quality factor Q is not too high. Thus, a more accurate model for the coupling coefficient is required to take the circuit losses into account when designing narrowband filters.In this paper, a method for accurate calculation of the coupling coefficient between two degenerate modes (in dual-mode filters) or two resonators in standard filters is presented and compared with the standard model using two example filters with different configurations and coupling types: one is fabricated and tested using a conventional conductor, the other is designed and simulated using a fictitious HTS. The idea for improving the narrowband performance to achiev...

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A superconducting thin film filter of very high wide-band rejection

Cited by 12 publications

References 4 publications

Em Full-Wave Analysis and Testing of Novel Quasi-Elliptic Microstrip Filters for Ultra Narrowband Filter Design

Em Full-Wave Analysis and Testing of Novel Quasi-Elliptic Microstrip Filters for Ultra Narrowband Filter Design

A high-performance narrowband high temperature superconducting filter

A new model to calculate the coupling coefficient for more accurate filter design and further development of narrowband-filter performance

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