Electronic scan

Electronic movement of the radar beam is essential when the radar must operate in many modes simultaneously. Another principal reason for going to electronic scan is the high failure rate of mechanically scanned antennas.

Electronic scans have been used successfully in large ground radars like the Nike MAR and abroad large ships, as in the Hughes radars on the carrier. The emphasis therefore has switched to a search for simpler scanning systems for use on small ships, in aircraft and on the battlefield where the radar must be transported by motor vehicle or even by men on foot.

Both phase-phase scanning and phase-frequency scanning are being applied for these systems. For either type of scan better ferrite phase shifters are needed that have greater power handling ability, lower RF losses and better temperature stability, require less drive power and cost less. Since even a small phase-phase array uses several thousand-phase shifters, the cost factor is anything but negligible.

A very important development has been the appearance of digital latching phase shifters. These devices use ferrite elements in waveguides that can be switched from one saturation state to the other by a video pulse and remain in the new state between pulses.

Ultra-thin films

Scientists at the Westinghouse Research Laboratories are "growing" materials in films only 10 atoms thick. It would take about 100 million of them, put one on the top of another, to make a pile of an inch high. A pile of 2,000 would equal the average wavelength of light. The films are made from both metals and insulating materials and are used in research on the physical properties of thin films, which are becoming of major importance for the fabrication of molecular electronic structures and other advanced micro-electronic devices.

The films are grown by depositing them from the evaporated material inside an ultra-high vacuum chamber developed especially for the purpose. The chamber creates pressures less than 10‾¹² of atmospheric pressure at sea level. This corresponds to the pressure in order in outer space at a distance of some 300 miles about the earth. At such pressures, contamination atoms of unknown composition deposit at a rate only one-millionth that of the material under study.

The vacuum chamber is a double-walled stainless steel vessel that is similar in appearance to a deep-sea diving bell. The space between the walls can be filled with liquid nitrogen to cool the walls to 320 degrees below zero Fahrenheit.

The task of radio-frequency amplifier

The radio-frequency (r.-f.) amplifier employed in a broadcast frequency receiver may differ from that used in a receiver serving other purposes of tuned to other frequencies. A broadcast receiver, for example, must be capable of amplifying at any frequency between 500 and 1500 kc. It must be easily changed from one frequency to another and its amplification at all frequencies within this band should be uniform. It selects and amplifiers too. Its task is much more difficult to perform.

The energy thrust upon the other form a given broadcasting station is a complex bit of wave motion. If the microphone is idle what comes from the antenna may be considered as a very narrow band called the carrier wave. If a single tone, say 1000 cycles, is put into the microphone, the antenna current has frequencies of not only 600kc in it but 599 and 601 as well. When music is broadcast the frequencies in the antenna may be varying between zero and 5000 cycles above and below the carrier from instant to instant. These frequencies on either side of the carrier are called the side bands. The characteristics of the transmitter must be such that each of these audio frequencies is given equal power compared to the others.