However, the use of cylindrical or biconical dipoles, despite using thin wires is preferable here. Generally, the driven element in corner reflector antennas is either a half-wave dipole or collinear dipoles and are present in parallel orientation at a certain distance from the vertex of the corner reflector. The figure below represents the vertical corner reflector antenna: This was proposed by John D Kraus in the year 1938 and is used at very high and ultra-high frequency ranges. Thus, an arrangement consisting of a driven element along with a corner reflector is known as a corner reflector antenna. More specifically, we can say, without the presence of a driven element, antenna arrangement is incomplete. However, without the presence of an element that provides electromagnetic wave to the surface of the reflector, a corner reflector can never be converted into a corner reflector antenna. Thus, can never be considered as a source element. This is so because a reflector is just a single element that is used to redirect the received energy in a particular direction. But one must not misinterpret a corner reflector with a corner reflector antenna. Till now we have seen how a corner reflector operates. This provides an improvement in the directivity by reflecting the received energy in the desired direction. The corner shaped reflectors facilitate confining the radiated energy within the metallic plate. We have already discussed in our previous article about reflectors that the major aim behind placing a reflector in an antenna arrangement is to improve its directivity. It reflects the wave in the direction from where these are originated and are regarded as a passive device. Thus, the direction of propagation of the waves gets reversed. This means for a dihedral structure the wave is reflected twice while in case of trihedral structure the wave is reflected thrice. More specifically, the principle of its operation is such that when an electromagnetic wave strikes the corner reflector then the incoming ray gets reflected from each electrically conductive surface once. It uses the law of optics that implies, the signal after reflection travels in the same direction from which it was received. And the most preferable value of α to form corner reflector is 90°. The angle forming the corner with two adjacent sheets is known as included angle and is denoted as α. The reason behind saying this is that it uses flat sheets or conducting sheets to form corner reflectors just be joining the sheets at a particular angle. This type of reflector is nothing but a modified form of the flat reflector. We know that parabola is a 2-dimensional structure and it is rotated about its axis in order to have a parabolic reflector which is a 3-dimensional structure. In parabolic reflectors, we have seen that the shape of the parabolic reflector corresponds to a paraboloid and it exhibits the properties of a parabola. This leads to improvement in directive gain offered by the antenna.Īlso, we have discussed parabolic reflectors. In our previous article, we have discussed that reflectors are used to collect and re-radiate the received electromagnetic energy in the desired direction. These reflectors exhibit simple structure and offer simplicity in design.
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