A W-band PIN diode single pole double throw (SPDT) switch with low insertion loss (IL) was successfully developed using a hybrid integration circuit (HIC) of microstrip and coplanar waveguide (CPW) in this paper. In order to achieve low loss of the SPDT switch, the beam-lead PIN diode 3D simulation model was accurately established in Ansys High Frequency Structure Simulator (HFSS) and the W-band H-plane waveguide-microstrip transition was realized based on the principle of the magnetic field coupling. The key of the proposed method is to design the H-plane waveguide-microstrip transition, it not only realizes the low IL of the SPDT switch, but also the direct current (DC) bias of the PIN diode can be better grounded. In order to validate the proposed design method, a W-band PIN diode SPDT switch is fabricated and measured. The measurement results show that the IL of the SPDT switch is less than 2 dB in the frequency range of 85 to 95 GHz, while the isolation of the SPDT switch is greater than 15 dB in the frequency range of 89.5 to 94 GHz. In the frequency range of 92 to 93 GHz, the IL of the SPDT switch is less than 1.65 dB, and its isolation is higher than 22 dB. Switch rise time and switch fall time of the SPDT switch are smaller than 29ns and 19ns, respectively. Good agreement between the simulations and measurements validates the design method.

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In this letter, a fractal structure used for the miniaturized design of microstrip bandpass filter (BPF) is presented. A new resonator called Greek cross fractal resonator (GCFR) in this paper was constructed by combining the proposed fractal structure with a traditional dual-mode meandered loop resonator. Three BPFs based on the new resonator with different orders iteration were analyzed. In addition, the mode-splitting characteristic and impact of the perturbation element on the performance of the BPFs were also investigated. The simulated results show that the new fractal resonator has a certain potential in the miniaturization design and the BPFs possess acceptable frequency characteristics. Therefore, the proposed fractal structure can be used as a candidate for miniaturization technology.

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The airborne and spaceborne SAR system are not universal access to a large area due to its higher cost and harsh demand conditions. This paper presents a vehicle millimeter wave SAR system. According to the features and application needs of the platform, this system uses range migration algorithm (RMA). Firstly, the system uses dechirping algorithm to deal with every echo. Then, we derive the two-dimensional frequency domain expression of the echo whose residual video phase (RVP) has been compensated and then analogize it to the spatial frequency domain to calculate the spatial frequency domain expression. Finally we complete the location reconstruction of the target. Due to the fan-shaped distribution of the signal distribution in the spatial frequency domain, there will be a large error if we reconstruct the location of the target directly. In this paper, we use stolt interpolation to turn the fan-shaped distribution into a rectangular distribution and the specific interpolation step is given. We also simulate the algorithm proposed in this paper. Finally, we use the vehicle millimeter wave SAR system to image for the actual scenario and the focusing effect of the image results is good to meet the demand. So the system can be applied to a variety of areas.