Exercises

I. Translate the following sentences into Chinese.

1. A very commonly used method of microwave measurements is based on the study of a standing wave pattern formed along the line because of the interference of incident and reflected waves.

2. Computations show a reduction of 6dB in the EM field intensity with the distance doubled, and an increase of 3dB in the intensity with the transmitted power doubled. This result provides verification to the algorithm used.

3. Like transfer of heat by conduction, convection and radiation, microwave heating can be considered as another mode of heat transfer, in which heat is produced directly at the location of the dielectric losses.

4. Operation of the radar is based on the measurement of the time it takes for a pulse transmitted from an antenna to get reflected by the object to be detected and to return at the antenna and the receiver.

5. Other motivations for using CAD in circuit design includes the wish to acquire confidence in a design that was accomplished by other means, and, not least in importance, a sense of curiosity or perhaps a desire to discover the unexpected.

6. The spacing between the repeating amplifiers is a function of the cable attenuation and the system bandwidth so that the gain provided by these amplifiers compensates for the loss introduced by the cable.

7. When the cut-off frequency is no less than the maximal frequency of the original signal, nor is it greater than the difference between the sampling frequency and the maximal frequency, the original signal may be completely rebuilt.

Ⅱ. Choose the word or phrase that is closest in meaning to the underlined part.

1. If these other charges and currents are comparable in size to the sources producing the above electromagnetic field, then a new net electromagnetic field will be produced.

A. make comparison with the size of the sources

B. are compared with the size of the sources

C. have similar size to the sources

D. take a common size of the sources

2. This range of wavelengths has led many to question the naming convention used for microwaves as the name suggests a micrometer wavelength.

A. has raised many questions about the naming habit

B. has caused many people to challenge the naming rules

C. has led many questions of the naming convention

D. has resulted in many problems in the naming tradition

3. NASA worked in the 1970s and early 1980s to research the possibilities of using Solar Power Satellite (SPS) systems with large solar arrays that would beam power down to the Earth's surface via microwaves.

A. shed solar energy to the Earth's surface from the satellite

B. set the satellite down to the Earth's surface with power

C. shut down the power on the Earth's surface from the satellite

D. switch off power to the Earth's surface from the satellite

4. As DoD urgently wanted military command and control networks that could survive a nuclear war, ARPA was charged with inventing a technology that could get data to its destination reliably even if arbitrary parts of the network disappeared without warning as a result of a nuclear attack.

A. win a nuclear war

B. be used in preparation of a nuclear war

C. avoid a nuclear war

D. be still operational after a nuclear war

5. At the present, state of the art microwave amplifiers and oscillator tubes can operate in a frequency range up to 40GHz and solid-state microwave devices up to 100GHz. A. recent and most advanced

B. high tech related

C. sophisticated

D. artistically manufactured

6. In such a fiber rays traveling at larger angles with respect to the axis have to traverse a longer path and hence take a longer time than those rays which propagate with smaller angles to the axis.

A. have transmitted over a longer distance

B. are bound to treat a longer way

C. must travel through a longer route

D. must deal with a longer trace

7. By keeping the off state slightly below threshold, the delay between the applied electrical pulse and the resulting optical output pulse is minimized; this delay must indeed not be more than the bit interval so that the optical pulse can accurately reproduce the input signal.

A. this delay must indeed be no more than one internal bit

B. indeed, this delay must exceed the bit of interval

C. as a matter of fact, this delay interval must be a little bit less

D. this delay must indeed be kept less than the spacing between data bits

8. Computations show a reduction of 6dB in the EM field intensity with the distance doubled, and an increase of 3dB in the intensity with the transmitted power doubled. This result provides verification to the algorithm used.

A. that, with a 6dB reduction, the EM field intensity is twice as strong

B. that the EM field intensity is decreased by 6dB as the range is doubled

C. that, in the EM field, intensity with double distance leads to a 6dB reduction

D. a 6dB intensity reduction causes a double distance in the EM field