In order to obtain the flow characteristics of sub-super-sonic mixing layer including velocity distribution, pressure distribution and development of mixing layer, experimental and numerical investigations were conducted. PIV technique was employed to measure the two-dimensional velocity distribution in the experiment while the standard k-ω turbulent considering the effect of compressibility was adopted to simulate the flow characteristic of mixing layer. The Mach number of subsonic stream and supersonic one was 0.11 and 1.32, respectively. The results show the flow of mixing layer is temporally transient. The interface between two streams lies initially as an approximately line segment; afterward, it becomes wrinkled and distorted; finally, it breaks up. The mixing layer develops linearly along streamwise direction in the time averaged velocity field with a growth rate of 0.135. The velocity and total pressure distributions in the mixing layer are self-similar.

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A high isolation and compact microstrip diplexer for broadband and wireless local area network (WLAN) application is proposed in this paper. It is achieved by using the combination of a broadband bandpass filter (BPF) composed of one open stub and two short stubs of different size loaded in 50Ω feed lines. The tapped stub can not only generate two zeros to deepen the stopband, but also connect other BPF without deterioration of in-band performance. Hence, the compact diplexer combines two BPFs without extra junction matching network. The mutual loading effect approximately equivalent to a coupled resonator can create one zero at the passband edge to improve the isolation. The proposed microstrip diplexer is designed and fabricated, and it has a 1dB fractional bandwidths (FBW) of 60% at 3.5GHz for broadband channel and 3% at 5.8GHz for WLAN channel . The simulated and measured results are presented and good agreement is obtained.