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  2. Huygens–Fresnel principle - Wikipedia

    en.wikipedia.org/wiki/Huygens–Fresnel_principle

    The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) states that every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere. [1] The sum of these spherical wavelets forms a new wavefront.

  3. Network protector - Wikipedia

    en.wikipedia.org/wiki/Network_protector

    However, if there is a fault on the secondary grid, the network protector is not designed to open its contacts up. The secondary fault will continue to be fed from the primary side of the system. In some cases, networks are designed with cable limiters (like fuses) to melt and disconnect the secondary fault under the right conditions. In other ...

  4. Patch antenna - Wikipedia

    en.wikipedia.org/wiki/Patch_antenna

    A patch antenna is a type of antenna with a low profile, usually consisting of a printed circuit board. It consists of a planar rectangular or circular sheet or "patch" of metal, mounted over a larger sheet of metal called a ground plane. It is the original type of microstrip antenna described by Howell in 1972. [1]

  5. Phased array - Wikipedia

    en.wikipedia.org/wiki/Phased_array

    The phase shifters delay the radio waves progressively going up the line so each antenna emits its wavefront later than the one below it. This causes the resulting plane wave to be directed at an angle θ to the antenna's axis. By changing the phase shifts, the computer can instantly change the angle θ of the beam. Most phased arrays have two ...

  6. Ancillary services - Wikipedia

    en.wikipedia.org/wiki/Ancillary_services

    Frequency control refers to the need to ensure that the grid frequency stays within a specific range of the nominal frequency. Mismatch between electricity generation and demand causes variations in frequency, so control services are required to bring the frequency back to its nominal value and ensure it does not vary out of range.

  7. 'Will they be able to take our home?': This Houston couple ...

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  8. Wavefront - Wikipedia

    en.wikipedia.org/wiki/Wavefront

    A wavefront sensor is a device which measures the wavefront aberration in a coherent signal to describe the optical quality or lack thereof in an optical system. There are many applications that include adaptive optics , optical metrology and even the measurement of the aberrations in the eye itself.

  9. 'Will they be able to take our home?': This Houston couple ...

    www.aol.com/finance/able-home-houston-couple-got...

    This Houston couple was tricked into a contract — to pay up to $67K — for 'free' solar panels. Here are 3 legit ways to get cash back for going green When a deal sounds too good to be true, it ...