What is the test ranges of antenna measurement?
What is the test ranges of antenna measurement?
A Compact Antenna Test Range (CATR) is a facility which is used to provide convenient testing of antenna systems at frequencies where obtaining far-field spacing to the AUT would be infeasible using traditional free space methods. It was invented by Richard C. Johnson at the Georgia Tech Research Institute.
What is the range of near-field?
From Figure 1, the near field extends for approximately 3.5 m. Stores with several entry doors often have a number of RFID antennas spaced across the entry area to give complete coverage because the field intensity falls rapidly with distance from the antenna.
What is compact antenna test range?
A Compact Antenna Test Range (CATR) allows electrically large antennas to be measured at a significantly shorter distance than would be necessary in a traditional far-field test range. Multiple-feed systems may be used to improve the far-field characteristics.
Why is the condition 2D2 λ chosen for far-field region?
In a far-field configuration, directivity is important because it is a good indicator of the far-field distance. Consider that directivity is related to the aperture size of the antenna. Thus, the 2D2/λ term will be small for low gain (low directivity) antennas and large for high gain (high directivity) antennas.
How are antennas tested?
The general approach to antenna tests is to position a known transmitter and antenna at a known distance away from the tested antenna. The tested antenna is connected to a known receiver. The magnitude of the transmitter output is known, as is the loss of any cabling.
Why near and far field is required for an antenna?
In the far-field region of an antenna, radiated power decreases as the square of distance, and absorption of the radiation does not feed back to the transmitter. However, in the near-field region, absorption of radiation does affect the load on the transmitter.
What are the far field conditions for an antenna?
The far field of an antenna is generally considered to be the region where the outgoing wavefront is planar and the antenna radiation pattern has a polar variation and is independent of the distance from the antenna.
What is a Catr chamber?
Market leading Compact Antenna Test Ranges (CATRs) provide the industry’s most accurate chambers for measuring Over-The-Air antenna performance and RF conformance tests. These chambers are configurable with different numbers and positions of probe antennas to support different use cases.
What is the reactive near field?
The reactive near field is the region where the fields are reactive i.e the E and H fields are out of phase by 90 degrees to each other. For propagating or radiating fields, the fields must be orthogonal to each other but in phase.
How do you check antenna resistance?
Connect one lead from the meter to the tip of the antenna, and the other to the radio pin — the piece at the end of the antenna cable that fits into the radio. The reading should be low, usually under 5 ohms; that means a good electrical connection between the tip of the antenna and the radio pin.
What is the near field range of antenna?
The figure-1 depicts near field antenna range. The distance or range from antenna upto 2*D 2 /λ is known as nearfield distance. Here D is the aperture diameter of AUT (Antenna Under Test) and λ is the operating wavelength. This antenna test ranges are usually used to test antenna indoors in small space.
Why antantenna Test Range is required?
Antenna test range is required in order to test and measure above mentioned antenna parameters. Selection of antenna test range depends on following parameters. The perfect antenna measurement depends on monitoring and control of following parameters other than the right antenna range selected as per need.
What is indoor far field range?
As entire equipments are located indoorand enchoic chamber is used the test facility is known as indoor far-field range. The figure-4 depicts outdoor far field antenna range. The test system consists of test antenna with receiver front end and positioner,source antenna and outdoor enclosure.
What is AUT (antenna under test) range?
Here D is the aperture diameter of AUT (Antenna Under Test) and λ is the operating wavelength. This antenna test ranges are usually used to test antenna indoors in small space. It uses small RF probe on one side and the AUT (Antenna Under Test) on the other side. The distance or seperation between the two is about 4 to 10 wavelength long.
