HIGHLIGHTED-Microwave-Communications.pdf

A loop antenna b sense antenna c quarterwave antenna

Info icon This preview shows pages 38–40. Sign up to view the full content.

View Full Document Right Arrow Icon
a) loop antenna b) sense antenna c) quarterwave antenna d) parabolic antenna 448. What is heard by earphones in the ADF? a) 3 kHz beat b) 1 kHz beat c) 2 kHz beat d) 5 kHz beat 449. If two bearing are determined from a radio beacon or station over a period of a few minutes, what else must be known to determine the ship’s position? a) speed b) elapses time c) ship’s course d) any of these 450. What important point regarding-loop RDF system maintenance? a) insulation at top of loop b) clean moving contacts c) oil bearing of loop d) any of these 451. Indicate which of the following frequencies cannot be used for reliable beyond-the-horizon terrestrial communications without repeaters: a. 20 kHz b. 15 MHz c. 900 MHz d. 12 GHz 452. A ship-to-ship communications system is plagued by fading. The best solution seems to be the use of
Image of page 38

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
a. A more directional antenna b. A broadband antenna c. Frequency diversity d. Space diversity 453. A range of microwave frequencies more easily passed by the atmosphere than are the others is called a a. Window b. Critical frequency c. Gyro frequency range d. Resonance in the atmosphere 454. Frequencies in the UHF range propagate by means of a. Ground waves b. Sky waves c. Surface waves d. Space waves 455. Tropospheric scatter is used with frequencies in the following range: a. HF b. VHF c. UHF d. VLF 456. When microwave signals follow the curvature of the earth, this is known as a. The Faraday effect b. Ducting c. Tropospheric scatter d. Iosnospheric reflection 457. Helical antennas are often used for satellite tracking at VHF because of a. Troposcatter b. Superrefraction c. Ionospheric refraction d. The Faraday effect 458. _______________ consists basically of a thin film strip in intimate contact with one side of a flat dielectric substrate, with a similar thin-film ground plane conductor on the other side of the substrate. a. Strip line b. Lecher wire c. Microstrip d. Stub 459. Waveguide is a a. Device used to determine the wavelength of a signal b. Hollow metal tube used for transmission of microwave energy c. Plastic tubular transmission line for high RF network d. Braided wire used for transmission of HF 460. Transmission lines which can convey electromagnetic waves only in higher order modes are usually called a. Coaxial cable b. Twisted pair c. Power lines d. Waveguides 461. In order to reduce cross-sectional dimensions, the waveguide to use is a. Circular b. Ridge c. Rectangular d. Elliptical 462. A signal propagated in a waveguide has a full wave of electric intensity change between the two farther walls, and no component of the electric field in the direction of propagation. The mode is a. TE1,1 b. TE1,0 c. TM2,2 d. TE2,0 463. When a particular mode is excited in a waveguide, there appears an extra electric component, in the direction of propagation. The resulting mode is a. Transverse electric b. Transverse magnetic c. Longitudinal
Image of page 39
Image of page 40
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern