对称耦合器综合优化方法与小型化研究

发布时间：2018-10-20 09:46

【摘要】：对称定向耦合器在微波和毫米波电路设计中应用十分广泛,随着通讯技术的不断发展,不论是军用频段还是民用频段都有向更宽频带拓展的趋势,所以对对称定向耦合器的频带和性能都提出了更高的要求。然而单节平行线耦合器很难实现宽频带和高性能,所以就需要设计多节对称耦合器,展宽频带和提高性能。对于多节对称定向耦合器的设计,如果采用传统设计方法很难在短时间内优化出好的结果,所以有必要提出一个更快速的对称耦合器综合优化方法。本文在总结前人的成果基础上,提出了一种新的对称耦合器综合设计的优化方法。该方法首先将等波纹函数用勒让德多项式展开,然后通过拟牛顿法和共轭梯度法求解勒让德多项式的展开系数。数值结果表明该方法的收敛速度远远快于传统的幂级数展开方法,而且能够对阶数极高的对称耦合器进行性能优化。为了验证综合优化方法的有效性,本文设计了一款宽带对称耦合器,频率范围为0.5-3GHz。综合优化方法对理想耦合线电路模型直接优化出了好的结果,而由于没有考虑各耦合节间的连接,所以还需在HFSS中进一步优化。在实际电路模型存在耦合节间不连续性问题,本文采用加载电容枝节进行了改善,经仿真与实物测试表明改善十分有效。耦合器的小型化也是目前发展的趋势之一,对于反向定向耦合器小型化设计,目前最主要的方法是采用弯折线法。虽然弯折线法会影响耦合器的隔离度,但总体来说对耦合器的性能影响比较小。另外,弯折线法也有很多局限性,比如,它一般适用于频率1GHz以下的频段,同时应用在多节耦合器中会加大耦合器走线的难度。本文还创新的提出了可重构法设计耦合器,给出了一种双频带耦合器的建模方法,经仿真验证可重构实现耦合器确实可行。但是由于可重构加入了PIN管,会恶化耦合器的性能。可重构法虽然会对耦合器的性能造成轻微的影响,但是能实现多个离散频段的耦合器,同时能缩小耦合器尺寸67%以上,这些都是传统设计方法不能达到的。
[Abstract]:Symmetrical directional coupler is widely used in microwave and millimeter-wave circuit design. With the development of communication technology, both military and civil frequency bands have the tendency to expand to wider frequency band. Therefore, the frequency band and performance of the symmetric directional coupler are required higher. However, it is difficult to achieve wide band and high performance of single parallel coupler, so it is necessary to design multi-section symmetric coupler to broaden the frequency band and improve performance. For the design of multi-section symmetric directional coupler, it is difficult to optimize the result in a short time if the traditional design method is adopted, so it is necessary to put forward a more rapid synthesis optimization method of symmetric coupler. In this paper, a new optimization method for the synthesis design of symmetric coupler is proposed on the basis of summing up the previous achievements. In this method, the equal-ripple function is first expanded by Legendre polynomials, and then the expansion coefficients of Legendre polynomials are solved by quasi-Newton method and conjugate gradient method. Numerical results show that the convergence rate of the proposed method is much faster than that of the traditional power series expansion method, and the performance of symmetric couplers with high order can be optimized. In order to verify the effectiveness of the synthetic optimization method, a broadband symmetric coupler with a frequency range of 0.5-3 GHz is designed in this paper. The synthetic optimization method directly optimizes the ideal coupled line circuit model, but it needs to be further optimized in HFSS because the connection between the coupling nodes is not considered. In the actual circuit model there exists the problem of coupling discontinuity between internodes. In this paper, the loaded capacitor segment is improved, and the simulation and physical test show that the improvement is very effective. The miniaturization of couplers is also one of the trends at present. The most important method for the miniaturization design of reverse directional couplers is the bending line method. Although the bending line method will affect the isolation of coupler, the overall effect on the performance of coupler is relatively small. In addition, bending line method has many limitations. For example, it is suitable for frequency band below frequency 1GHz, and it will increase the difficulty of coupler wiring when it is applied in multi-section coupler. This paper also proposes a new reconfigurable method to design couplers, and presents a modeling method of dual-band couplers. The simulation results show that reconfigurable couplers are feasible. However, the performance of the coupler will be deteriorated because of the reconfigurable addition of the PIN tube. Although the reconfigurable method has a slight effect on the performance of couplers, it can realize multiple discrete band couplers and reduce the size of couplers by more than 67%, which can not be achieved by traditional design methods.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN622

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