Radar and Antenna Systems Quiz

The ratio of the power density radiated by an antenna in a given direction to the power density that would be radiated by an isotropic antenna with the same total power.

An antenna that radiates power equally in all directions.

A type of antenna consisting of a wire wound in the shape of a helix. It can radiate circularly polarized waves when the diameter of the helix is comparable to the wavelength.

A type of radiation where the electric field vector rotates in a circle. The direction of rotation can be clockwise or counterclockwise.

A mode of radiation where the helix radiates perpendicular to its axis. This occurs when the diameter of the helix is much smaller than the wavelength.

A mode of radiation where the helix radiates along its axis. This occurs when the diameter of the helix is comparable to the wavelength.

The angle between the axis of the helix and the direction of a tangent to the helix at a point.

The length of the helix measured along the wire, excluding the ground plane.

The ratio of the radiation intensity of an antenna in a given direction to the radiation intensity of an isotropic radiator fed by the same power. It measures how well an antenna focuses its radiation in a specific direction.

The maximum value of directivity, achieved in the direction of strongest radiation. It represents the antenna's best ability to focus its signal.

The overall efficiency of an antenna, which accounts for energy losses due to impedance mismatches, conduction, and dielectric effects.

The ratio of the radiation intensity of an antenna in a given direction to the radiation intensity that would be obtained if the power fed to the antenna were radiated isotropically, considering the antenna's efficiency.

A measure of power loss due to reflections caused by impedance mismatch between the transmission line and the antenna.

The efficiency of the antenna related to the polarization of its radiated waves, the direction of the electric field.

The efficiency of the antenna considering the losses due to conduction currents within the antenna structure.

The efficiency of the antenna considering the losses due to energy dissipation within the antenna's dielectric material.

The angle at which the lowest lobe of a rhombic antenna's radiation pattern points towards the horizon. This angle is influenced by the antenna's height above ground.

The length of each side of a rhombic antenna, which determines the operational frequency range and directionality.

The height of a rhombic antenna above ground level. This influences the angle of elevation and radiation pattern, especially for low-angle radiation.

The optimal relationship between the leg length (L), antenna height (h), and operational frequency, ensuring efficient radiation and low-angle propagation.

The use of multiple conductors for each leg of a rhombic antenna, which helps maintain a stable characteristic impedance over the operational frequency range.

An antenna's ability to focus radiation in a specific direction, measured in decibels (dB). It represents how effectively the antenna concentrates power towards the desired location.

The range of frequencies over which an antenna operates efficiently. It's often expressed as a ratio of the highest to lowest frequencies.

Undesirable radiation lobes emitted by an antenna in directions other than the intended main beam, often reducing signal quality and causing interference.

The ratio of the effective aperture area (Ae) to the physical aperture area (Ap) of an antenna. It represents how efficiently the antenna utilizes its physical size to capture and radiate power.

The area of an antenna that effectively captures power from an incoming electromagnetic wave. It is related to the antenna's physical size and shape.

The solid angle subtended by the main beam of an antenna, indicating the area over which the antenna radiates most of its power.

The ratio of the power density radiated by an antenna in a given direction to the power density that would be radiated by an isotropic antenna with the same input power. It measures how effectively an antenna focuses power in a specific direction.

The minimum detectable signal strength that a radar receiver can detect.

The reduction in signal strength caused by atmospheric absorption, scattering, and other factors.

The area of a target that reflects radar signals back to the receiver.

The minimum detectable signal strength required for a radar system to successfully detect a target.

A type of antenna that consists of a straight conductor, typically a quarter-wavelength long, mounted perpendicular to a ground plane.

An antenna composed of two straight conductors of equal length, usually spaced apart by a distance of approximately half a wavelength.

A directional antenna that uses multiple elements, including a driven element, a reflector, and possibly directors, to enhance signal strength in a specific direction.

A type of antenna used in HF communications that utilizes a diamond-shaped wire structure to achieve a broad bandwidth.

An antenna with a wire wound in a helical shape, often used in satellite communication due to its broadband properties.

An antenna with a wire wound in a spiral shape, also known for its broadband capabilities.

A type of antenna that resembles a horn and is used in microwave applications, often as feeds for parabolic reflectors.

A highly reflective antenna commonly used in radar systems and satellite communication, reflecting signals to a focal point.