In a radar square law diode pulse detector,
What is the minimum Signal to Noise ratio into the detector when the RF bandwidth into the detector is very much greater than the detector video output bandwidth
Answers
Answer:
Goofus and Gallant design detectors
Long before Beavis and Butthead provided wholesome entertainment, Goofus and Gallant were teamed in a magazine called Children's Highlights that your parents would subscribe to if they were afraid that you were in danger of being a juvenile delinquent. Goofus and Gallant predate Frankie Lymon singing the JD song which was a stretch for him and the Unknown Editor alike.... but it is arguable that Frankie was more cuddly and lovable.
Detectors
Goofus and Gallant each build a detector using the same diode. Goofus uses waveguide, Gallant uses coax. Which of the boys achieves a higher voltage for a given RF input power? This is a great question for interviewing a microwave design candidate to put him/her to shame. Today only 1 out of 100 microwave engineers know the answer, back in the 1950's, 90% of microwave engineers would have known as they would have been schooled in the RadLab series. Do you know the answer? Click here when you give up.
History of detectors
Detectors have been around since the earliest attempts at the parlor trick of wireless transmission of electrical energy. Marconi's incredible feat in 1902 of receiving a Morse code signal across the Atlantic used what was known as a coherer as the receiver. Coherers are not exactly detectors but perform the same function. The coherer is filled with sharp metal filings, and starts to conduct when a weak RF signal is passed through it, in a process akin to micro-welding. Unfortunately it keeps on conducting after the RF is absent, hence the "decoherer" which repeatedly slaps against it and loosens the filings back to their non-conductive state. The DC current is passed to a pair of headphones, and in a sound-proofed room the operator waits for a ridiculously weak audio signal and writes it down, then solves the message like a puzzle for all of the letters he missed. The coherer below is displayed at the Twin Lights Museum in Highlands New Jersey, site of a 19th century Marconi wireless station.