Design And Fabrication Of Microwave Power Termination And Attenuator

Because of the advantages of light weight, small size, and ease of integration, the Microwave power match loads(MPMLs) and attenuators are widely used in microwave communication systems and microwave circuits. The MPMLs connected to filters, antennas, circulators, amplifiers and other components in microwave circuits to provide protection. when these components are mismatched, the MOMLs will absorb excess reflected power of each component. Microwave power attenuator is a thin film device used in microwave circuits to reduce the input signal without distortion of the signal. The excessive power in MPMLs and attenuator is converted to heat and dissipated into the air through the resistive film material. This paper studies the properties of TaN thin film materials and designed different types of MPMLs and attenuatorsIn the aspect of selection and processing of ceramic substrate, the BeO ceramic substrate is selected because of its good thermal conductivity, but the surface flatness of mechanical polished BeO ceramic substrate is poor,. This paper use the method of coating glass glaze on the surface of BeO to flattening the substrate, after planarization process, the Surface flatness has improved significantlyIn terms of studying the performance of resistive film material, this paper sputter TaN film on the BeO and study the influence to the film properties of different conditions of N2/ Ar2. By component analysis we found that with the increasing proportion of N2, the nitrogen-rich phase appears. The thickness of the film, sheet resistance, TCR and other performance tests found that with the increase proportion of 2 the thickness of TaN film decrease from 444 nm to 199 nm, the square resistance increase from 8Ω/sq to 70Ω/sq and the resistivity increase from 355.2μΩ?cm to 1393μΩ ?cm and because of the resistance stability of nitrogen-rich phase is poor, the TCR of film is greater.In the design of the device, we use ePhysics and HFSS software. Two MPMLs are designed: termination 1 is working at 0-20 GHz and the power load is 3W; termination 2 is working at 0-3.5GHz, the power load is 30 W. Two attenuators are designed: attenuator 1 working at 0-6GHz,the attenuation is 9dB; attenuator 2 working at 0-5GHz,the attenuation is 12 dB.In the design of the device, with the use ePhysics HFSS simulation software is designed to match the load: a matched load frequency is 0-20 GHz, using the power of 3W; frequency of the matched load 2 is 0-3.5GHz, using the power of 30 W. While the design of two attenuators: 9db attenuation of the attenuator, the frequency of 0-6GHz, attenuation of 12 db attenuator frequency of 0-5GHz. Thermal simulation software using ePhysics matched load distribution, load simulation results show that the temperature of the matched load resistor films rated power does not exceed 125 degrees Celsius. Useing ePhysics software to simulate the heat distribution of MPMLs, the simulation results show that the temperature of the MPMLs do not exceed 125℃.In the aspect of production and testing devices, use evaporation coating, lithography, etching and other processes to produce electrodes and use peeling method to pattern the resistive film, after slicing produce the devices are finished. Production test fixture, use a microwave vector network analyzer to test the performance of the device. Load power on MPMLs to test temperature distribution. Test results showed that: terminal 1 and terminal 1 VSWR of less than 1.4; attenuators VSWR less than 1.2; 1h matches the temperature load applied power is less than 125 ℃Production and testing devices: the use of evaporation coating, lithography, etching and other processes produce electrodes. Reactive magnetron sputtering using resistive film production, the use of graphical resistive film peeling method, after slicing produce the finished device. Production test fixture, use a microwave vector network analyzer to test the performance of the device, the power load on the matched load test matched load resistor film temperature distribution. Test results showed that: a matched load VSWR of less than 1.4; attenuator VSWR less than 1.2; Load one hour power the temperature of both terminals is less than 125℃, meet the design requirements.