Dielectric resonator filters for UMTS systems

Dielectric Resonator filters can provide high selectivity and low insertion loss similar to cavity filters but with smaller size and weight. They have long been used in satellite communication and more recently became of significant interest in terrestrial applications. In this paper the design of two UMTS dielectric filters (transmit and receive) have been presented

Precise microwave characterization of MgO substrates for HTS circuits with superconducting post dielectric resonator

Accurate data of complex permittivity of dielectric substrates are needed for efficient design of HTS microwave planar circuits. We have tested MgO substrates from three different manufacturing batches using a dielectric resonator with superconducting parts recently developed for precise microwave characterization of laminar dielectrics at cryogenic temperatures. The measurement fixture has been fabricated using a SrLaAlO3 post dielectric resonator with DyBa2Cu3O7 end plates and silver-plated copper sidewalls to achieve the resolution of loss tangent measurements of 2 {\times} 10-6. The tested MgO substrates exhibited the average relative permittivity of 9.63 and tan {\delta} from 3.7 {\times} 10-7 to 2 {\times} 10-5 at frequency of 10.5 GHz in the temperature range from 14 to 80 K.Comment: 6 pages, 8 figures, 3 table

Political masculinities, crisis tendencies, and social transition: Toward an understanding of change

This introduction to the special issue on “Political Masculinities and Social Transition” rethinks the notion of “crisis in masculinity” and points to its weaknesses, such as cyclical patterns and chronicity. Rather than viewing key moments in history as points of rupture, we understand social change as encompassing ongoing transitions marked by a “fluid nature” (Montecinos 2017, 2). In line with this, the contributions examine how political masculinities are implicated within a wide range of social transitions, such as nation building after war, the founding of a new political party in response to an economic crisis, an “authoritarian relapse” of a democracy, attempts at changing society through terrorism, rapid industrialization as well as peace building in conflict areas. Building on Starck and Sauer’s definition of “political masculinities” we suggest applying the concept to instances in which power is explicitly either being (re)produced or challenged. We distinguish between political masculinities that are more readily identified as such (e.g., professional politicians) and less readily identified political masculinities (e.g., citizens), emphasizing how these interact with each other. We ask whether there is a discernible trajectory in the characteristics of political masculinities brought about by social transition that can be confirmed across cultures. The contributors’ findings indicate that these political masculinities can contribute to different kinds of change that either maintain the status quo, are progressive, retrogressive, or a mixture of these. Revolutionary transitions, it seems, often promote the adherence to traditional forms of political masculinity, whereas more reformatory transition leaves discursive spaces for argument

Computations of unloaded Q0-Factor and resonant frequency of the TE011 mode Hakki–Coleman dielectric resonators with coupling structures using ANSOFT HFSS

Microwave characterization of materials using dielectric resonators is based on measurements of the Q-factor of the resonator containing a sample under test and on the loss equation for the test structure. The loss equation contains geometrical factors, which are calculated assuming an ideal metallic cavity of the resonator. In this paper a rigorous analysis of cylindrical parallel plate dielectric resonators has been performed to assess the influence of the presence of coupling holes and cables on the unloaded Q-factor and resonant frequency. Calculations have been done for the TE011 mode resonators with differing cavity to dielectric diameter ratio, conductivity of the cavity material, loss tangent and relative permittivity of the dielectric rod, position of the coupling loops and size of the coupling cables. Results have shown that Qo-factors calculated for real resonators were smaller than Qo-factors for ideal resonators. Also this paper presents a brief history of analysis of dielectric resonators

Surface resistance of YBa2Cu3O7 superconducting films on LaAlO3, NdGaO3 and Al2O3 substrates at varying microwave power levels

Nonlinear performance of High Temperature Superconductors at high RF power levels is still one of major constrains in mass market applications of HTS films in cellular and PCS communication systems. We have measured surface resistance of YBa2Cu3O7 films on several substrates and compared their microwave power-handling capabilities. We have found that for high-quality YBCO films the losses of films on LaAlO3 substrate are the smallest followed by films on NdGaO3 and then on Al2 O3. Also the best quality films exhibited linear behaviour up to very high RF fields. Power-handling properties of YBCO on Al2O3 are improved by very good thermal conduction of sapphire. Best films deposited with the thermal co-evaporation and the off-axis sputtering techniques have been found to be of comparable quality

Microwave characterization of (La, Sr)(Ai,Ta)O3 using TE011 mode dielectric resonator

The permittivity and loss tangent of a dielectric material can be estimated from precise measurement data of the Q-factor and resonant frequency of a dielectric resonator containing the material under test. We have characterized an (La,Sr)(AI,Ta)O, (LSAT) single crystal of the cylindrical shape using TE011 mode dielectric resonator in two enclosures at a frequency of 15.5 GHz at temperatures from 15 K to 293 K and an LSAT planar sample at 9.7 GHz using a post cryogenic TEo1, resonator. Our measurements\ud have shown that permittivity of LSAT is in the vicinity of23 and exhibits a peak at temperature of 190 K. We have also studied the temperature coefficient of frequency of the LSAT substrate. Due to the weaker temperature dependence of permittivity of LSAT substrates, HTS devices and circuits fabricated on LSAT can be more stable than on Lanthanum Aluminate

Protection of primary users in areas where cognitive radio is deployed

Cognitive radio systems and 'whitespace' devices are radio systems that can use unoccupied spectrum to establish communications links. These systems, when properly implemented, would deliver an increase in the utility of the spectrum, thus increasing service delivery, without causing harmful interference to existing licensed systems. Spectrum may be unoccupied either temporally or geographically. In either case we refer to this fortuitous access to the spectrum as 'auxiliary access'. To permit such access in otherwise occupied spectrum a system of protection factors must be developed which ensure the protection of the `primary' system while still realistically permitting operation of the dynamic or whitespace system. This paper proposes a set of transmission levels that would enable the use of cognitive devices in suitable bands

Narrowband superconducting filters for mobile communication

Supcrconducting planar filters exhibit higher selectivity, bigger out-of-band rejection and smaller interference\ud between adjacent channels than metallic planar filters. Using ideas of a modified hairpin, the Chebyshev approximation and cross coupling between non-adjacent resonators, we have designed two HTS filters utilising YBa2CU307-6 thin films on a 58mmx 14mmxO.3mrn LaAlO3 substrate. A 12-pole superconducting bandpass filter for centre frequency of 1.84 GHz and bandwidth of 5 MHz exhibits simulated passband insertion loss of 0.1 dB and the out-of-band rejection of 50 dB at I MHz from the passband. A HTS bandstop filter was designed using the same type of the resonator as the bandpass filter to obtain 50 dB attenuation for the frequency from 1.621 GHz to 1.625 GRz (Iridium satellite)

Measurements of intrinsic losses of high temperature superconducting thin films: surface resistance and conductivity

[Extract] Research devoted to measurements of dc amd ac losses of HTS materials in bulk, thick and thin film forms followed immediately their discover twenty five years ago [1]. Apart from pure love of scientific discovery this interest was also driven by possible HTS mass market applications. The dc resistance was measured by the four probe technique [2]. But for testing of surface resistance several measurement techniques used before for Low Temperature Superconducting films, metallic films and dielectric materials have been trialed by various groups [3-13]