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An X-band four-channel T/R module is designed and fabricated based on SICL(Substrate Integrated Coaxial Line). The module's transmitting channel has high gain and high power and the RF signal is transmitted through SICL to reduce signal leakage. Combined with the method of metal frame, it decreases the crosstalk between the input and output ports of transmitting channel, enhances the signal shielding ability, and reduces the risk of self excitation. Test results show that the dimension of the TR module is $110\text{mm}^{\ast}80\text{mm}^{\ast}10\text{mm}$ , with transmitting power ≥ 35W, receiving gain >35dB, noise figure < 3dB, phase consistency ≤± 15 ° and gain consistency ≤ 1dB.

As a core part of the power amplifier, the power synthesis unit is concerned to meet the launch requirement of electromagnetic equipment. This paper present two kinds of design methods covering 6 to 18 GHz. One approach is adopt an unequal powder combination with a 1:2 between 2-way powder divider and impedance to realize odd equal power output by high and low impedance circuit matching; an alternate approach is a sector broadband synthesis circuit structure of multi-section to achieve higher power signal transmission through cavity or micro-strip circuit model. It can be seen from the simulation results that for both synthesis circuits, the interpolation loss is less than 0.5 dB and the out-put wave ratio is less than 1.3, which meets the high power synthesis demand of broadband power amplifier.

In order to meet the requirements of electromagnetic countermeasure and radar systems, a miniaturized variable frequency module from 8 to 16GHz is proposed. The module adopts the modular design idea, which is implemented by the vertical overlay assembly of two independent modules, which reduces the plane size. Using multi-layer media substrate combined with bare-chip micro-assembly process, the component size is reduced and circuit integration is improved. In order to realize the requirements of generalization, the module adopts a three-stage mixing scheme, integrates the functions of phase shift, attenuation, pre-selected filtering, and can be powered by a single point from +8 to +20V, making it convenient for use. The measured results show that the compact ultra-wide band down converter meets all the specifications, and can be widely used in various occasions.

In this work, the flow features of coaxial rotors measured in water tunnel are investigated via particle image velocimetry technique. The experiments are conducted using a two-bladed model-scale coaxial rotor and a single rotor with the same geometry. Some noticeable flow features are found. For the coaxial rotor in hover, there is an annular region radially inboard of the lower rotor disk, where there are almost no intrusions from the upper rotor wake. At the same time, upwash occurs at the outboard edge of the lower rotor, while no such phenomenon occurs near the upper rotor blade tip. Sometimes, two upwash phenomena are found both at the blade tip and root in the single-rotor case. For both the single and coaxial rotors in forward flight, there is a sudden velocity change at about 0.7 R on the retreating side. From comparisons with the prior performance experiments, it can also be found that mutual interferences are playing a positive role in the hovering coaxial rotor configuration. The previously prescribed wake models can well describe the tip vortex trajectories of the single rotor and coaxial rotor in hover and forward flight, especially at high advance ratios. However, in this experiment, some special features are also found slightly different with that of the experiment conducted in air. Some valuable results obtained from this experiment would be helpful to reasonable designs of coaxial helicopters in the future.