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In this paper, an improved through line-based fixture de-embedding method is proposed. By interpolating the original measurement S-parameter magnitude and phase of the vector network analyzer and obtaining the fixture parameters, the time resolution and time range changes of the existing method can be avoided. At the same time, the parameters of the fixture can be obtained without changing the instrument settings, and the applicability of the fixture de-embedding method based on the through line is improved. Finally, the effectiveness of the method was verified by testing the high-speed USB type C cable.

Signal integrity issues caused by reflections and crosstalk are important issues that must be considered in the design of high speed signal processing circuits. In the design process of high speed signal processing circuit, HyperLynx software is introduced to simulate the key signal circuits, and the signal integrity theory is used to scientifically analyze the problems found in the simulation. The influence of reflection, crosstalk and other factors on the high speed circuit is reduced, the signal transmission quality is significantly improved, and finally achieves the success of this design.

new two-step method is proposed to accurately analyze time-domain impedance based on VNA frequency-domain data in this paper. The method is based on one port reflection scatter parameter to construct time-domain response of the DUT. The method proposed in this paper is mainly composed of two steps. In the first step, we calibrate the instrument at the test port, and then use the traceable standard impedance air line for time domain setting calibration; the second step is to obtain the impedance characteristics of the device under test based on above setting. Finally, a practical measurement example of stepped impedance air line is given to verify the effectiveness of the method.

In order to implement the new functions such as pulse measurement and spectrum analysis in vector network analyzer, it is necessary to improve the sampling rate, passband bandwidth, and other performance indicators of the signal processing system of the vector network analyzer receiver, and the anti-aliasing filter in the sampling circuit is of great importance to realize the above indicators. Therefore, an anti-aliasing filter suitable for high-performance vector network analyzers is designed in this paper, which not only has controllable bandwidth, but also has the advantages of small in-band insertion loss, large bandwidth, strong stop-band suppression, and high flatness in-band. The feasibility of this solution is verified in high performance vector network analyzer.

In order to make the multi-port vector network analyzer meet the needs of large bandwidth, high-sampling rate and high-speed real-time data processing, this paper presents a transmission and reception technology of multi-channel high-speed sampling data, based on the use of high performance ADC, FPGA and other integrated circuits. According to the signal integrity theory, this paper designs the technology from two aspects, respectively, the hardware layout and FPGA logic, which reduce the reflection signal when the high-speed sampling signal is transmitted, and avoid the error caused by the excessive transmission delay between the multi-channel high-speed differential signals. Finally, a multi-channel high-speed sampling data synchronization transmission and reception technology is achieved, and it is verified in vector network analyzer.

A new zero-bias model and compensation procedure for the intermediate frequency (IF) signal processing system of the vector network analyzer (VNA) based on neural network is proposed in this paper. This procedure can be used to four IF channels with different conditions. The structure of the zero-bias compensation procedure in one port is given first. Then for four different channels, the same method is applied. The zero-bias is modeled by radial basis function neural network and the IF signal is compensated via the analysis based on the model. Finally, the proposed method is tested via AV3672 series VNA and the experiment shows that the method can well eliminate the zero-bias of the IF signal, and it is effective for zero-bias model and compensation.

The paper presents a new fault diagnosis method for the intermediate frequency (IF) signal processing system of the vector network analyzer (VNA) based on dynamic fuzzy neural network (DFNN). This paper gives the structure of the fault diagnosis with three test points in one port first. Then for four different ports, it chooses the same method. The fault diagnosis is done by on-line self-organizing DFNN, and the structure and parameter identification is made in the on-line process without default values of structure and network parameters. It is the first time to introduce the DFNN into the fault diagnosis of the VNA IF system. Finally, the simulation experiment shows that the method can well approximate the nonlinear feature of the fault, and it is effective for fault diagnosis.

The distribution and characteristics of LDH isoenzymes in different tissues of 25 species of vertebrate were comparatively analysed by discontinuous polyacrylamide gel disk electrophoresis, combined with experiments on heat and urea inhibition. The result showed that in different tissues ofCtenopharyngodon idellus, Carassius, ayratus, Trichiurus haumete andMiichthys miiuy in addition to the distribution of LDH isoenzymes, composed of A and B subunits, a E4 isoenzyme band, moving very fast to the positive pole, was detected in the eye tissue ofTrichiurus haumele and a F4 isoenzyme hand, moving very slow to the positive pole, was found in liver and kidney ofCtenopharyngodon idellus. The A4 isoenzyme band was found in different tisseues ofPleuronichthys cornutus, inhabiting on the bottom of the ocean. From the amphition to the mammal, with the exception ofHyta arboreu immaculata, Chinnemys reevesii, Trionyx sinensis, Gallus gallus domesticus andCorvus macrorhynchos, which have special electrophoretic behaviours. In different tissues of the other animals distributed the five kinds of tetrameter of isoenzyme bands composed of A and B subunits. Meanwhile, the C4 isocnzyme band was detected in the testicle tissues of animals. The C4 bandof Rattus norvegicus caraco andLepus timidus located between the bands of LDH4 and LDHS and the C4 band ofErinaceus europaeus, a primitical animal, located to the farther side of LDHS and moving very slow to the positive pole. The distribution characteristics of LDH isoenzymes of different classes of vertebrates were compared and it was suggested that no parallism existed between the changes of LDH isoenzyme zymograms and phylogeny of vertebrates.

The constituents of essential oil of Asternovi-belgii were analyzed by GC and GC/MS. 18 peaks were separated by GC and 14 compounds were identified. The identified constituent’s accounts for 99.10% of GC peak areas of essential oil. The major chemical constituents of Asternovi-belgii are β-Pinene (38.33%), α-pinene (31.23%), and thujene (16.71%).