What Do You Know About Antenna And Radio Wave Propagation? Quiz

An antenna is a device that converts high-frequency current into an electromagnetic wave. It is used for transmitting or receiving radio waves, allowing communication between devices. Antennas are commonly used in radio and television broadcasting, wireless communication systems, and satellite communication. They are designed to efficiently radiate or receive electromagnetic waves, making them an essential component in wireless communication technology.

Most omnidirectional horizontally polarized antennas are used in the VHF (Very High Frequency) and UHF (Ultra High Frequency) range of frequencies. These frequencies are commonly used for television broadcasting, FM radio, and various communication systems. Omnidirectional antennas are designed to radiate or receive signals in all directions, making them suitable for applications where signals need to be transmitted or received from multiple directions.

An antenna with a gain of 3 dB increases the output of the transmitter by 1000 times. The gain of an antenna is a measure of its ability to focus and amplify the signal it receives. A gain of 3 dB corresponds to a doubling of power, and since power is proportional to the square of the amplitude, this results in a 1000 times increase in the output of the transmitter.

A half-wave dipole antenna radiates more power in certain directions compared to an isotropic antenna, which radiates equally in all directions. The gain of an antenna is the ratio of the power radiated in a particular direction to the power radiated by an isotropic antenna. A gain of 2.15 dB indicates that the half-wave dipole antenna radiates approximately 2.15 times more power in the desired direction compared to an isotropic antenna.

When the antenna increases 3.3 times, the radiated power increases by a factor of 10.89 times. This is because the radiated power is directly proportional to the square of the antenna length. So, if the antenna length increases by 3.3 times, the radiated power will increase by (3.3)^2 = 10.89 times.

A rhombic antenna is a type of non-resonant antenna. It consists of a diamond-shaped array of wires or elements that are not resonant at the operating frequency. The rhombic antenna is designed to have a high gain and directional radiation pattern, making it suitable for long-range communication. Unlike other options listed, such as the folded dipole, end-fire array, and Yagi-Uda antenna, the rhombic antenna does not rely on resonance for its operation.

Entropy is the amount of uncertainty in a system of symbols. It is a measure of the randomness or disorder in a system. In information theory, entropy quantifies the amount of information that is missing or unknown in a message or data. Higher entropy means higher uncertainty and lower predictability. In thermodynamics, entropy is a measure of the disorder or randomness of a system. It represents the number of ways in which the system can be arranged or the number of microstates that are consistent with a given macrostate.

Beamwidth is the measurement of unilateral antenna properties of directivity. It refers to the angular width of the main lobe of an antenna's radiation pattern. It indicates the directionality of the antenna and its ability to concentrate the radiated power in a specific direction. A narrower beamwidth signifies a more focused and directional antenna, while a wider beamwidth indicates a broader coverage. Therefore, beamwidth is the appropriate measurement for assessing the unilateral antenna properties of directivity.

A discone antenna is designed to have a vertical polarization. This means that the electric field of the radio waves transmitted or received by the antenna is oriented in a vertical direction. This type of polarization is commonly used in applications such as broadcasting and communication systems. By having a vertical polarization, the discone antenna can effectively transmit and receive signals in a specific direction, optimizing its performance for the intended use.

The gain of an antenna refers to its ability to focus and direct the transmitted or received signal in a specific direction. An isotropic antenna radiates equally in all directions, while a Hertzian dipole has a specific radiation pattern that concentrates the energy in one direction. Therefore, the gain of a Hertzian dipole over an isotropic antenna is 1.76 dB, indicating that the Hertzian dipole is more efficient in transmitting or receiving signals in a specific direction.

A dummy antenna is used in testing the transmitter to prevent interfering with other stations. A dummy antenna is a non-radiating load that simulates the impedance of an actual antenna. It absorbs the transmitted power and prevents it from being radiated, ensuring that the transmitter's signal does not interfere with other stations.

A critical phased array antenna is designed to maintain a specific ratio between the currents of its elements, which in this case is 5%. Additionally, it is required to have a phase angle of 3°. This configuration allows the antenna to have precise control over the direction of its main beam, making it suitable for applications where accurate beam steering is necessary. A critical phased array antenna is different from a broadband or wideband array, which are designed to operate over a wide range of frequencies. An end fire array is a type of antenna that radiates or receives most of its energy in the forward direction, but it does not necessarily have the same current ratio or phase angle requirements as a critical phased array.

Null refers to the regions in an antenna pattern where there is little to no radiation or reception of signals. In this context, "Very low signal strength in antenna" suggests that there is a lack of signal reception, which aligns with the concept of null in antenna patterns. Therefore, the correct answer is null.

Space diversity is the best solution to fading because it involves using multiple antennas at different locations to receive the same signal. By having antennas placed at different positions, the effects of fading caused by multipath propagation can be minimized. This is because the signal received at one antenna may experience fading, while the signal received at another antenna may not be affected. By combining the signals from different antennas, a more reliable and robust signal can be obtained, reducing the impact of fading.

In the context of antennas, a "bay" refers to a section that can function as a complete antenna on its own. This means that it has all the necessary components and characteristics to transmit or receive signals effectively. The other options, such as "top loading" and "quarterwave," do not represent a complete antenna by themselves and would require additional sections or components to function properly. Therefore, "bay" is the correct answer as it represents a standalone antenna section.