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Design procedure of a novel transmission line low‐pass filter is presented. The filter has a flexible rejection response for a prescribed cut‐off frequency and an in‐band ripple factor. It is compact by using a Z‐shaped coupled‐line section, which is loaded with open‐circuited stubs. All of the transmission line elements are identical in electrical length, and the impedances can be calculated by solving certain specific equations according to prescribed in‐band specifications. The simulated results show that the circuit can generate low‐pass responses with third‐, fifth‐, and seventh‐order filtering functions. The filter order depends on the number and position of the loading stubs. For verification, two sample filters with cut‐off frequency of 0.5/0.3 GHz are fabricated using a three‐/five‐layer PCB process, which generate seventh‐order low‐pass filtering responses with good selectivity. The experimental results agree well with the predictions.

It is shown that a well-designed lumped $LC$ loop network with a phase inverter can exhibit perfect reflectionless filtering response at its all four ports. The network is composed of two pairs of symmetrical $LC$ ladder circuits, in which one pair is obtained from lowpass transformation at a prescribed frequency based on a special lowpass prototype, and the other pair is from highpass transformation based on the same prototype at the same frequency. The input power, at any port, is divided into the two adjacent ports in the frequency domain through different paths of the loop. Each path between any two ports nearby can be treated as a mono-functional filter, whereas the adjacent two paths work as two filters with complementary responses. The overall circuit performs as a generalized diplexer without a specified “common” or “separation/combination” port. By using a numerical equation solver, the element values of the reflectionless lowpass/highpass prototype filter of order one, three, five, and seven are given. Then, the values of order nine, eleven, thirteen, and fifteen are obtained by using the optimization method. Other filtering functions such as bandpass/bandstop or dual-band can be easily implemented with the proposed prototype by using the standard frequency transformation method. For verification, two sample filters are fabricated and measured. The experimental data agree well with the predictions.

Response diversity of a commensurate line bandpass filter is described and discussed. It is found that a stub-loaded ring topology can generate different bandpass responses in a single band or two symmetric bands, depending on the line admittances in the topology. For a single band, the response can be designed to be an equiripple delay, Chebyshev in magnitude, or elliptic in magnitude. For dual bands, the out-band attenuation curve can be adjusted with almost unchanged in-band matching. A generalized synthesis algorithm, supporting both the single- and dual- band applications, is given to calculate the admittance of each line element, according to the prescribed in-band specifications, e.g., ripple factor and cut-off frequencies. Further study reveals that the admittance of the line segment between the stubs is the key element dominating the response type in the single-band case. When the admittance is positive, zero, and negative, the response is an equiripple delay, Chebyshev in magnitude, and elliptic in magnitude, respectively. To validate the synthesis algorithm, four filter sets with different responses are given and simulated through a transmission line model. For circuit verification, a microstrip filter with a single-band elliptic response is designed, fabricated, and measured, of which the negative admittance line is realized by a coupled line section with shorted ends. The experimental results show that the filter achieves elliptic response successfully. The measured 3-dB fractional bandwidth is 86.6% centered at 0.97 GHz, within which the minimal insertion loss is 0.88 dB at 0.81 GHz. Furthermore, two transmission zeroes beside the passband are observed clearly at 0.31 and 1.59 GHz, offering a sharp rejection in the stopband.

Purpose We examined the efficacy and safety of thalidomide (THD) for the prevention of delayed nausea and vomiting in patients who received highly emetogenic chemotherapy (HEC). Patients and Methods In a randomized, double-blind, active-controlled, phase III trial, chemotherapy-naive patients with cancer who were scheduled to receive HEC that contained cisplatin or cyclophosphamide-doxorubicin/epirubincin ≥ 50 mg/m2 regimens were randomly assigned to a THD group (100 mg twice daily on days 1 to 5) or placebo group, both with palonosetron (0.25 mg on day 1) and dexamethasone (12 mg on day 1; 8 mg on days 2 to 4). Primary end point was complete response to vomiting—no emesis or use of rescue medication—in the delayed phase (25 to 120 h). Nausea and anorexia on days 1 to 5 were evaluated by the 4-point Likert scale (0, no symptoms; 3, severe). Quality of life was assessed by the European Organization for Research and Treatment of Cancer QLQ-C30 version 3 questionnaire on days −1 and 6. Results Of 656 patients, 638 were evaluable: 317 in the THD group and 321 in the control group. Compared with placebo, delayed and overall (0 to 120 h) complete response rates to vomiting were significantly higher with THD: 76.9% versus 61.7% ( P < .001) and 66.1% versus 53.3% ( P = .001), respectively. Rates of no nausea were also higher in the THD group (delayed: 47.3% v 33.3%; P < .001; overall: 41% v 29.6%; P = .003), and mean scores of anorexia were lower overall (0.44 ± 0.717 v 0.64 ± 0.844; P = .003). Adverse effects were mild to moderate. The THD group had increased sedation, dizziness, constipation, and dry mouth, but experienced better quality of life after chemotherapy. Conclusion Thalidomide combined with palonosetron and dexamethasone significantly improved HEC-induced delayed nausea and vomiting prevention in chemotherapy-naive patients.

Two new equivalences in transmission line (TL) networks are proposed. The first one is found between a shunt fed stepped-impedance ring and a T-shaped TL network with a short-circuited series stub. Both the networks are composed of TL segments with the same electrical length. By using the Y and the ABCD matrices, an equivalent condition can be obtained, which is independent in frequency. Meeting the condition, the two networks with different topologies could generate exactly the same response. As the counterpart of the first one, the second equivalence is found between a series fed ring and a T-shaped network with an open-circuited shunt stub. The two equivalences are useful in circuit modelling and analysis; and provide extra design flexibility in circuit implementations.

A new all-pass filter APF is proposed. The APF is based on a symmetrical ring, consisting of four sections of transmission line, which are identical in electrical length, different in characteristic impedance. Two input/output ports are connected orthogonally to the ring. The APF is analyzed by using the odd-even model, and the all-pass condition is then theoretically obtained. Meeting the condition, the circuit is all-pass in frequency, but nonlinear in transmission phase. The nonlinear transmission phase with frequency may be adjusted by changing the lines' impedances, while remaining the all-pass property. Then the APF is used to design a wideband 90i¾? differential phase shifter with adjustable bandwidth. Samples are designed, fabricated and measured. Good agreements are achieved among the theoretic, numerical and experimental results. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:191-195, 2014.

Nanoporous carbon/graphene composites (NCGC) are synthesized via one-step hydrothermal approach combining carbonization, where phenol and formaldehyde are used as carbon sources and triblock copolymers F127 as template. Transmission electron microscopy (TEM) and nitrogen adsorption measurements show that the synthesized NCGC samples possess high surface area over 400 m2·g−1 and mesoporous structures with interconnected pores. The electrochemical studies demonstrate that Pt catalyst with NCGC as support exhibits better eletrocatalytic activity for methanol oxidation as compared to the catalyst taking widely-used VulcanXC-72 as support. In addition, the potential formation mechanism of NCGC is discussed.

The bandstop behaviour of a stepped impedance microstrip ring is studied. The ring is composed of four sections of microstrip line, which are equal in electrical length, but different in impedance. When the impedances of the lines meet the condition of rotational symmetry, a bandstop response could be obtained. At the central frequency of the stopband, the electrical length of the lines is 90°. By tuning the lines' impedances, the bandwidth could be finely adjusted, typically from 0.5 to 40%. Prototypes are designed, fabricated and measured. Good agreements are observed between the measured and the simulated data. The measured data shows that the 3 dB bandwidth is 24%, with a rejection level of −32 dB at the central frequency 1.99 GHz. In addition, the measured matching within the passband is good, as predicted.

A compact ultra-wideband filter is presented. The filter consists of a section of coupled microstrip-line and a short-ended stub. It has a simple structure and small size (4.7×6.2 mm2), but exhibits good performance. The filter has been investigated numerically using the simulator IE3D, and samples were fabricated and measured. Measured results show that the filter has a fractional bandwidth of 103.2% (from 3.05 to 9.55 GHz) and minimal insertion loss of −0.4 dB. The measured in-band return loss is better than −15.0 dB.