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A nickel-catalyzed arylation of aromatic amines using arylzinc reagents with trimethylammonium salts formed in situ is developed. Compared with previous systems using ammonium salts as the starting materials and complexes of pre-prepared nickel catalysts, this reaction directly employed an N, N -dimethyl(het)arylamine as the coupling partner and commercial Ni(COD)2 / TMEDA as the catalyst, greatly simplifying the experimental procedure, decreasing the cost, and being especially suitable for scale-up production processes. [ABSTRACT FROM AUTHOR]

A Ka-band microstrip antenna based on PIN diodes with accurate extraction of equivalent circuit parameters for pattern reconfigurability is proposed in this work. With the increase in operation frequency, the parasitic effect introduced by PIN diodes has tremendous influence on the performance of reconfigurable antennas; hence, the conventional equivalent circuit parameters of the PIN diodes are not applicable for higher-frequency applications, such as millimeter-wave circuits and antennas. Therefore, accurate equivalent circuit models of the conventional PIN diodes are essential in the millimeter-wave reconfigurable antenna design. Based on the combination of simulation and experimental results, accurate equivalent circuit model parameters for the millimeter-wave range of the PIN diode are extracted, with a pattern-reconfigurable antenna being developed afterwards. The proposed antenna consists of two PIN diodes, two interdigital capacitors, an L-shaped slot, and their bias networks. Particularly, the interdigital capacitors are utilized to isolate direct current (DC) from radio frequency circuits, which is able to improve the economic efficiency of the antenna notably as compared with conventional chip capacitors in the Ka-band. By combining a suitable arrangement of the diodes' location and the DC bias networks, the main beam direction of the proposed antenna can be switched between −60° and 60°. To demonstrate the proposed idea, a prototype antenna is fabricated and measured. The measured results agree with the simulation quite well, with a good performance around 30 GHz and a gain greater than 5 dBi for both modes being achieved. [ABSTRACT FROM AUTHOR]

This paper introduces a versatile design method for reconfigurable metasurfaces based on the Pancharatnam–Berry phase theory. Unlike traditional reconfigurable metasurfaces that require designing independent surfaces for specific applications, leading to a significant time investment for designers to learn and create, this study proposes a foundational, invariant metasurface. By selectively metallizing holes or inserting metal cylinders, it achieves nine available functionalities. Regardless of the chosen operating function, the metasurface demonstrates high efficiency at 8.2 GHz, with amplitude loss less than 1 dB. Additionally, when operating in phase modulation mode, the design provides a 360 ° phase adjustment range and a 30 ° phase step. A prototype containing 31 × 31 units (425.6 × 425.6 mm 2) has been fabricated and tested under function 7 (TM and RHCP transmission phase modulation). Measurement results confirm the metasurface's capability for polarization conversion and phase modulation at the frequency of 8.2 GHz. [ABSTRACT FROM AUTHOR]

This paper presents an E-band substrate integrated waveguide (SIW) dual-polarized antenna system, which consists of an orthomode transducer (OMT) and a dual-polarized horn antenna. On the basis of a two-layer substrate design, the function of OMT is realized by utilizing an SIW section to excite TE10 mode for the vertical polarization, a quasi-coaxial stripline to excite quasi-TEM mode for the horizontal polarization. And also, a slot line transition is placed at the common port of the two structures for impedance matching with the ridge SIW dual-polarized horn antenna. In this way, the dual-polarized horn antenna is designed with an exponential ridge structure simultaneously for better impedance matching and higher efficiency of the antenna. To verify the functionality of the proposed integrated OMT-antenna structure, an experimental prototype is fabricated and measured, and a good agreement is found between its simulation and measured results. Over the frequency range of 83–87 GHz, return loss better than 10 dB at all ports and cross-polarization less than −25 dB are obtained. The maximum antenna gain is about 14 dBi for the horizontal polarization and 15.2 dBi for the vertical polarization. It is believed that the proposed OMT-antenna design is suitable for ultrahigh capacity millimeter-wave backhaul applications in future wireless communication systems. [ABSTRACT FROM PUBLISHER]

ABSTRACT Two planar matched loads using substrate integrated waveguide (SIW) and absorbing material are presented. The magnetic-loss absorbing material is cut into horn and concave shapes and loaded into SIW sections respectively to form two SIW matched loads. Measured results of the proposed SIW matched loads show comparable agreement with their corresponding simulations. Moreover, the proposed matched loads exhibit fractional bandwidths of 46.1 and 68%, respectively with a return loss over 18.5 dB, as well as system integration capability, low complexity and low cost, which demonstrate their suitability for Ka- and Q-band applications. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1174-1178, 2017 [ABSTRACT FROM AUTHOR]

Two size‐reduced dual‐band half‐mode substrate integrated waveguide (HMSIW) cavity filters double‐side‐loaded with the conventional and stepped‐impedance complementary split‐ring resonators (SICSRRs) are presented. The SICSRR can exhibit larger equivalent electrical length than the conventional CSRR and thus provides a method to implement size‐miniaturisation. By loading both CSRR and SICSRR into the two sides of the HMSIW cavity, a dual‐band resonator is formed. Since sizes of the CSRR and SICSRR on the two sides are controlled independently, the two passbands of the proposed resonator can be tuned flexibly. With the proposed HMSIW–DS–SICSRR cavity resonators, two dual‐band filters are realised. Compared to other dual‐band SIW filters, the two proposed dual‐band filters can achieve sized‐reduction about 48.5 and 50%, with the measured results in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

A half‐mode substrate integrated waveguide (HMSIW) bandpass filter loaded with modified complementary split‐ring resonators (CSRRs) is presented. The modified CSRR, realised by utilising horizontal–asymmetrical stepped‐impedance (SI) structure in the conventional CSRR, can enhance the equivalent capacitance and inductance of the CSRR and consequently shift the resonant frequency downwards. Therefore, for the same operation frequency, the SICSRR can occupy smaller size than the conventional CSRR, which provides a promising method to achieve size‐reduction in microwave circuits. To verify the effectiveness of miniaturisation introduced from the proposed HMSIW‐SICSRR resonator, a two‐pole bandpass filter is implemented. Moreover, the measured results are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

In this article, we propose an effective mixed extracting method for anisotropic constitutive parameters of periodically loaded substrate integrated waveguide (SIW). This method takes the advantage of both scattering parameters retrieval theory and the equivalent homogeneous medium dispersion analysis, which could accurately and effectively extract the equivalent constitutive parameters of the periodically loaded SIW. With this method, the corresponding constitutive parameters of the six typical patterns of periodically loaded SIW schemes are accurately extracted, verified, explained, and compared for their performance. It can be used to quantitatively predict the miniaturization potential of each unit cell and sequentially evaluate the performance as an integrated component. In addition, in terms of application, with the aid of equivalent parameters extracted by the proposed method, a slow-wave SIW evanescent mode filter centered at 12.64 GHz with a frequency bandwidth of 300 MHz is synthesized, fabricated, and measured. In the meanwhile, the theory of slow-wave evanescent mode filter is further consummated, by introducing the dual factors of enhanced permittivity and permeability, as well as analyzing respective advantages in filter synthesis. Measurements and simulation results show good agreement, which embodies the role of the method in guiding the design of actual microwave devices. [ABSTRACT FROM AUTHOR]

In this paper, an inductor-loaded slow-wave substrate integrated waveguide (SIW) is presented and studied. The proposed structure features a number of unique propagation properties. First of all, the inductance value imposed along the transverse direction will affect the phase velocity and cutoff frequency of the waveguide simultaneously. Second, the inductance value in the longitudinal propagating direction will only affect the phase velocity but make no difference on the cutoff frequency. Based on the aforementioned characteristics, the size of structure could be controlled by separately tuning the loaded inductor along the transverse direction and longitudinal propagating direction. More importantly, it is released on the interrelationship between the phase velocity and cutoff frequency in the proposed guiding-wave structure. The feature will be beneficial to the design of leaky-wave antenna and matching circuits for SIW circuits. Finally, experimental results demonstrate that with the increasing of loaded inductance, a reduction of 35% in cutoff frequency is achieved compared with the conventional SIW counterpart. The phase velocity is also reduced by 35% with the increasing of the loaded inductor, which contributes to a miniaturized longitudinal dimension for a given electrical length. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a 3.5 GHz size-miniaturized microstrip bandpass filter based on folded stepped-impedance resonators (FSIR) structure is presented for frequency synthesizer application to achieve a moderate wide stopband performance and an enhanced sideband selectivity performance by two transmission zeros (TZs). The filter is composed of four half-mode FSIRs, where two FSIRs in the middle consist of a tri-mode resonator which produces a TZ, and a pair of 180-degree feed ports produce another TZ. After the filter is fabricated and measured, its measurement results are agreed with its simulated ones very well, and show its in-band (1dB bandwidth from 3.3 GHz to 3.7 GHz) insertion loss is less than 1.6 dB, its sideband suppression is 45dB at 260MHz away from the upper sideband, as well as its stopband rejection is 26 dB far to the fourth harmonic of the center frequency. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:60-62, 2017 [ABSTRACT FROM AUTHOR]

Tunable radio-frequency (RF) components are pivotal elements in frequency-agile and multifunctional systems. However, there is a technical barrier to achieve miniaturized fully electrically tunable RF components. This paper provides and demonstrates the efficacy of a first unique design methodology in developing fully electrically tunable RF components by integrating ferromagnetic [e.g., permalloy (Py)] and ferroelectric (e.g., lead zirconate titanate) thin-film patterns. Py thin film has been patterned in nanometer scale to improve its ferromagnetic resonance frequency for RF applications. Tunable inductors are developed with the utilization of different thicknesses of Py thin film, which show over 50% increment in inductance and over 4% in tunability with dc current. More tunability can be achieved with multiple layers of Py thin film and optimized thickness. A fully electrically tunable slow-wave RF transmission line with simultaneously variable inductance and capacitance density has been implemented and thoroughly investigated for the first time. The measured results show that a fixed phase shift of 90° can be achieved from 1.5 to 1.85 GHz continuously by applying external dc current from 0 to 200 mA and external dc voltage from 0 to 15 V, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] The c1/c1 CYP2E1 genotype is a significant risk factor for ATDH. [•] That concomitant slow acetylator NAT2 genotype may further increase this risk. [•] These genotypic patterns are risk factor in an Asian population. [ABSTRACT FROM AUTHOR]