New Delay Line

Components or devices used for signal delay are called the delay line. In recent years,along with the rapid development of electronic industry,delay line is widely used in precision oscilloscope,color TV,computer,industrial process control,modern radar systems and so on. Testing is an important part of the designing of T/R module. Usually we use coaxial line to simulate the propagating distance from the transmitter to the receiver. In this paper we design a delay line to instead the coaxial line. Comprehensively considering the advantages and disadvantages of delay line,we do some analysis on the transmission property of substrate integrated waveguide,and design a new kind of delay line used for T/R module testing.Substrate Integrated Waveguide(SIW)is a new kind of microwave transmission line in these years which can be widely used in microwave and millimeter wave circuit. The substrate integrated waveguide has advantages of both of the rectangular waveguide and the microstrip,such as high Q,low loss just like rectangular waveguide; small size,low profile,low cost,easy to be integrated like microstrip. The design index of delay line which is based on technology of substrate integrated waveguide is, working at X-band and delay time of 1 ns, the test results of the delay line have an ideal effect.Finally this paper introduces a kind of automatic gain control (AGC) circuit used for T/R components,the gain of the circuit decreases as the intensity of signal rises, it compresses the dynamic range of signal,then the signal can be easily handled.