High Temperature Superconducting NEMP Monitoring Receiver Front-End

Nuclear explosions monitoring is an important means of obtaining the required nuclear information and is a major component of national defense security nuclear protection.By detecting the spectral distribution and energy flux density of nuclear electromagnetic pulses,the parameters of nuclear explosions can be obtained and the types of nuclear explosions can be identified.Surveillance of nuclear explosions has an irreplaceable advantage of using spaceborne monitoring precept but faces the problem of weak signals due to the far distance of nuclear electromagnetic pulse propagation.In order to solve this problem,it is necessary to adopt the receiver front end with high sensitivity,high dynamic range,strong anti-interference ability,low noise figure and low loss.Conventional receiver front-end performance requirements do not meet,so the use of high-temperature superconducting receiver front-end.The front-end composed by the high-temperature superconducting filter,low temperature and low noise amplifier.The high-temperature superconducting receiver designed in this paper is designed to operate in the 77 K environment that shields the solar radiation from the Earth's background radiation.The operating frequency is in the VHF band.The high temperature superconducting filter uses a lanthanum aluminate dielectric substrate with a dielectric constant of 23.75 and a thickness of 0.5 mm.The size of filter after the miniaturization technique is 127 × 41 mm,the index of which is that the return loss is less than-21.54 d B,Rectangular coefficient is 1.48,the center frequency insertion loss is 0.1555 d B,out of band suppression greater than 100 d B.The LNA uses a Rogers 4350 B substrate with a dielectric constant of 4.36 and a thickness of 0.762 mm,measuring 50 x 40 mm.At 77 K,the gain is 22.70 ~ 22.33 d B and the in-band gain ripple is less than 0.4d B.The return loss S11 is less than-15.56 d B and the return loss S22 is less than-15.72 d B.The front end of the HTS receiver has a noise figure of less than 0.6d B and a gain of about 21 d B at an operating temperature of 77 K.The input and output reflection coefficients are all less than-15 d B,the out-of-band rejection is greater than 80 d B and the minimum detection signal is about-96 d Bm.The dynamic range About 111 d B.The front end of the sensitivity and anti-jamming capability than conventional receivers have greatly improved,which also indicates that the superconducting receiver in nuclear explosion monitoring has great potential application.