The Effect Of Variable Load To Transmission Characters Of The Two-ports Network

With the fast development in electronic information technology,the matching load, which is the problem of circuit analysis,still has remarkable significance.For example, the two-port filter network will reflect a good character tested by network reflectoscope reflector.But when fixed to a system,due to transmission characters,it needs to be tune to a better situation.Its character has changed when it is put back to the network reflectoscope reflector.That is why it's important to consider the load effect to the filter network.When design a two-port filter or matching network,the first to be considered is the transmission character sensitivity about the load.We refer a network,which is not sensitivity to the load,as minimum mismatch network.The article firstly considers 5-order low-pass Butterworth,Chebyshev,Bessel and Elliptic filter,and presents a minimum mismatch filter network using the method of Monte Carlo analysis.The method can present a resolution to the problem of mismatch to some degrees. And also it can make the filter to have no ripple or to have equi-ripples in the passband. But this method has a bottleneck.In order to break through the bottleneck,pi-type attenuator comes up.It has the minimum eneger loss and the maximum range of the load resistance floption.This article discusses the feasibility of the pi-type network and how to design a minimum mismatch pi-type network.It also gives some illustrations of the pi-type filter network using the 5-order Butterworth filter.