Gain Standard Antennas

Gain Standard Antennas are required to determine the calibration factors for a wireless test lab. Over-the-Air (OTA) measurements of a wireless device must be converted to values of Effective Isotropic Radiated Power (EiRP) in order to calculate values for Total Radiated Power (TRP). These calibration factors are the total loss from the center of the test zone to the power measurement device connected to the measurement antenna. This loss is measured by placing an antenna of known gain at the center of the test zone. The calibration factor is the difference between the power into the gain standard and the power measured by the power measurement device offset by the gain of the gain standard antenna.

Since the calibration factors are applied to each and every data point, any error in the gain of the gain standard is transferred directly into the calibration of TRP. The gain of each gain standard antenna is measured using the three antenna method so that measured gain is determined independent of any gain transfer standard.

VA-100-D Series Gain Standard Dipoles

The Series VA100-D Gain Standard Dipoles were designed as calibration standards for wireless test labs. Errors in the calibration of a wireless test lab are translated into every measurement of TRP or TIS, so accurate calibration is critical to maintaining a low measurement uncertainty.

There are three critical characteristics of the calibration antenna:

1. Its gain must be accurately known.
2. It is desirable that its pattern be symmetrical so that it does not have to be oriented in a particular direction.
3. It must have a low VSWR so that it accepts the power delivered to it.

Each VA100 dipole is independently calibrated using the three antenna method. Although time consuming, this method provides an accurate measurement of the gain of the antenna without requiring a gain transfer standard. During the manufacturing process each VA100 is carefully adjusted to for a symmetrical azimuth pattern. Typical pattern asymmetries are less than ±0.05dB.

Additional Information:

  VA-100-D Series Dipoles-Data Sheet

VA-100-H Series Gain Standard Horns

At frequencies above 2600MHz, dipoles become less attractive as gain standards. The Series VA100-H are low gain rectangular horns that are individually calibrated using the three antenna method to provide a gain standard with a low gain uncertainty. Two models are provided covering the frequency range of 2600-3950MHz and 3950-6000MHz.

Additional Information:

VA-100-H Series Horn-Data Sheet

Model LPA-1 Broadband Gain Standard

Although narrow band coaxial dipoles offer the optimum in low gain uncertainty, calibrating a wireless test lab over a wide range of frequencies is a tedious task which can take many hours and is prone to mistakes. As a result many wireless test labs are calibrated infrequently. There is a risk that the characteristics of an element in the signal path will change thus invalidating the calibration and hence the measurement. In this case many devices could be measured erroneously before the error is recognized, and the cost impact of such an event can be significant.

The LPA-1 Broadband Gain Standard strikes a balance between a low gain uncertainty and a broadband device that allows very fast range calibration. A unique method is used to calibrate the Model LPA-1.  A gain transfer measurement is made from calibrated dipoles at the range length at which it will be used and with the same model measurement antenna. This takes out the effects of both range length and the movement of the phase center vs frequency resulting in a very accurate transfer of the gain of the dipole to the gain of the LPA.

Using the Model LPA-1, it is possible to reduce the range calibration time by a factor of 10 while simultaneously significantly reducing the chance of operator error.

Additional Information:

LPA-1 Broadband Gain Standard Data Sheet

"Broadband Gain Standards for Wireless Measurements"