ARP (antenna reference point)

An antenna reference point (ARP) is a point on an antenna or an array of antennas that serves as a standard reference for measuring the location and performance of the antenna or array. It is an important concept in the design, installation, and calibration of antenna systems, especially in the field of wireless communication.

The ARP is defined as the point on the antenna or array where the specified antenna gain is measured. In most cases, the ARP is located at the physical center of the antenna or array, although it can be offset from the center in some designs.

The ARP is used as a reference point for measuring the performance of an antenna or array in terms of its radiation pattern, gain, directivity, polarization, and other parameters. The radiation pattern of an antenna or array is the directional distribution of the radiated energy, which can be visualized as a three-dimensional plot of the power density as a function of the direction relative to the antenna. The gain of an antenna or array is the ratio of the radiated power in a given direction to the input power to the antenna or array, expressed in decibels (dB). The directivity of an antenna or array is the ratio of the maximum gain in a given direction to the average gain over all directions, also expressed in dB.

The ARP is also used as a reference point for measuring the location of an antenna or array in space. The location of the ARP is defined with respect to a coordinate system, such as a global positioning system (GPS) or a local coordinate system, which is used to determine the position of the antenna or array relative to other objects or reference points. The location of the ARP is typically specified in terms of its latitude, longitude, and altitude, although other coordinate systems may be used depending on the application.

The ARP is an important concept in the design of antenna systems because it affects the performance of the antenna or array in terms of its radiation pattern, gain, directivity, and other parameters. The location of the ARP relative to the physical center of the antenna or array can affect the shape and orientation of the radiation pattern, as well as the gain and directivity of the antenna or array. For example, if the ARP is offset from the center of the antenna or array, the radiation pattern may be skewed or distorted, which can affect the coverage area and signal strength of the antenna or array.

The ARP is also important in the installation and calibration of antenna systems because it provides a standardized reference point for measuring the performance of the antenna or array. By measuring the gain, directivity, and other parameters of the antenna or array at the ARP, it is possible to determine whether the antenna or array is performing as designed and to adjust its position and orientation if necessary to optimize its performance.

The ARP is also used in the certification and testing of antenna systems by regulatory agencies such as the Federal Communications Commission (FCC) in the United States. The FCC requires that the gain of an antenna be measured at the ARP and that the location of the ARP be specified in terms of its latitude, longitude, and altitude. This ensures that the gain of the antenna is accurately measured and that the antenna is located in a specified location relative to other objects or reference points.

In summary, an antenna reference point (ARP) is a point on an antenna or an array of antennas that serves as a standard reference for measuring the location and performance of the antenna or array. The ARP is defined as the point on the antenna or array where the specified antenna gain is measured and is typically located at the physical center of the antenna or array. The ARP is used as a reference point for measuring the performance of an antenna or array in terms of its radiation pattern, gain, directivity, polarization, and other parameters, as well as for measuring the location of the antenna or array in space relative to a coordinate system. The ARP is an important concept in the design, installation, calibration, and testing of antenna systems, especially in the field of wireless communication.

One application of the ARP concept is in the design of phased array antennas. A phased array antenna consists of a large number of antenna elements that are arranged in a specific pattern to create a desired radiation pattern. Each element in the array is connected to a phase shifter that adjusts the phase of the signal transmitted or received by the element. By controlling the phase of each element in the array, it is possible to steer the radiation pattern in a specific direction without physically moving the antenna.

In a phased array antenna, the ARP is typically located at the center of the array and is used as a reference point for measuring the phase and amplitude of the signals transmitted or received by each element in the array. The phase and amplitude of each element are adjusted so that they add constructively in the desired direction and cancel out in other directions, creating a highly directional radiation pattern.

The ARP is also important in the installation of antenna systems, especially in applications where multiple antennas are used, such as in a cellular network. In a cellular network, multiple antennas are installed at a base station to provide coverage over a large area. The antennas are typically mounted on a tower or other structure and are oriented in different directions to provide coverage in different sectors.

In the installation of the antennas, it is important to ensure that the ARPs of all the antennas are located at the same height above ground and are oriented in the same direction. This ensures that the signals transmitted or received by the antennas are in phase and add constructively in the desired direction, maximizing the signal strength and coverage area.

The ARP is also used in the calibration of antenna systems, especially in applications where high accuracy is required, such as in the aerospace industry. In the aerospace industry, antennas are used in satellite communication, radar, and navigation systems, where high accuracy is required for reliable operation.

In the calibration of antenna systems, the ARP is used as a reference point for measuring the performance of the antenna or array in terms of its radiation pattern, gain, directivity, and other parameters. The calibration process involves measuring the performance of the antenna or array at various frequencies and orientations and comparing the results to a reference standard. Any deviations from the standard are then corrected by adjusting the position, orientation, or other parameters of the antenna or array.

The ARP is also important in the testing of antenna systems, especially in applications where regulatory compliance is required. Regulatory agencies such as the FCC in the United States require that the gain of an antenna be measured at the ARP and that the location of the ARP be specified in terms of its latitude, longitude, and altitude.

In the testing of antenna systems, the ARP is used as a reference point for measuring the gain, directivity, and other parameters of the antenna or array, and for verifying compliance with regulatory requirements. The testing process involves measuring the performance of the antenna or array at various frequencies and orientations and comparing the results to the regulatory requirements. Any deviations from the requirements are then corrected by adjusting the position, orientation, or other parameters of the antenna or array.

In conclusion, the ARP is an important concept in the design, installation, calibration, and testing of antenna systems. It serves as a standardized reference point for measuring the location and performance of the antenna or array, and is used to ensure that the antenna or array is performing as designed and meets regulatory requirements. The ARP is an essential tool for achieving high accuracy and reliability in antenna systems, especially in the field of wireless communication and aerospace applications.