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This paper presents principles of a down-converted mixer for four sub-harmonic and proposes a particle swarm optimization algorithm as a global search algorithm, and the performance equation is used as the assessment of the mixer circuit optimization method. Dielectric substrate adopts Electronic Materials with RF/Duroid 5880 whose dielectric constant is 2.20 and 5mil in thickness. The optimization algorithm can quickly get optimal results. The simulation results show that this mixer achieves higher 1 dB compression point, loss of frequency conversion which is less than 15 dB and good linearity.

This paper introduces the basic structure of narrow-band FIR filter and conducts detailed analysis on the various components of narrow-band FIR filter. Based on the CIC and HBF, this paper further designs narrow-band FIR filter with the sampling rate of 100 KHz. The materials of filter adopt the piezoelectric ceramic vibrator with high mechanical quality factorand high stability .Moreover, the simulation results indicate that this filter can greatly reduce the calculation amount and storage capacity so as to satisfy the real-time processing requirements of the signals.

The traditional K-means clustering algorithm prematurely plunges into a local optimum because of sensitive selection of the initial cluster center. Hierarchical clustering algorithm can be used to generate the initial cluster center of K-means clustering algorithm. The geometric features of input data can achieve a good distribution by means of pretreatment and feature extraction and selection. In the learning of fuzzy neural network, Java language is used to write source code of the algorithm. The experimental results show that new algorithm has improved the clustering quality effectively.

This paper presents principles of a down-converted mixer for four sub-harmonic designed by ADS software. The LO and RF frequencies are 23GHz, 92-94GHz respectively. The structure of ridge waveguide to microstrip transitions is optimized by CST simulation software, and W-band signals are directed to mixer RF side. The simulation results show that this mixer achieves higher 1 dB compression point, loss of frequency conversion less than 15 dB and good linearity.

Intermittent intensity clutter in wind profiling radar severely interferes with the identification and spectrum estimation of atmospheric echo signals. In order to remove such clutter, a method based on Fractional Fourier transform (FrFT) is presented. The proposed method makes use of energy concentration property of intermittent clutter in fractional Fourier frequency domain. Not only the intermittent intensity clutter can be removed in the fractional Fourier frequency domain by using a narrow band-stop filter, but also the atmospheric signal in the time domain can be reconstructed after removing the clutter. Computer simulations have verified the effectiveness of the method.