What is Antenna Pattern?
Textbook definition of antenna pattern or antenna radiation pattern is a graphical representation of the radiation properties (e.g. TRP, gain, efficiency, EIRP, directivity, phase or polarization) of the antenna under test (AUT) as a function of space.
Antenna Pattern Measurement Techniques
Until recently, the two dominant approaches for testing and evaluation of antenna parameters were near-filed and far-field measurement techniques. In the near-field range method antenna emissions are measured in the radiating-near-field region. The results are then projected to the far-field with well-developed and proven algorithms e.g. to offset RF reflections, mutual coupling between the AUT and the measurement antenna/probe, etc. This is critical because most antennas are intended to operate in the far-field region. A direct far-field measurement method can be performed in outdoor or indoor environments. Smaller antennas can be measured in an anechoic chamber. However, testing larger antennas often requires a remote open-air-test-site (OATS) consisting of a large area in a rural environment to avoid reflections. Both antenna pattern measurement techniques are costly and require longer times for Antenna Designers and Wireless Engineers to debug their designs, to do rapid prototyping, and to explore new designs, materials and geometries.
Novel Approach to Antenna Pattern Measurement: Very-Near-Field
RFxpert is a desktop antenna pattern measurement system that characterizes antennas without the need for a chamber. It provides far-field patterns, bisections, EIRP and TRP in less than a second. Novel near-field results, including amplitude, polarity and phase give insights into the root causes of antenna performance challenges and help troubleshoot far-field radiation patterns.
How Does It Work?
RFxpert measures the magnetic field (H-Field) in two orthogonal directions using H-field probes and projects this data to the far-field using the planar aperture distribution to angular spectrum transformation or plane wave spectrum (PWS) transformation. A second custom algorithm then adjusts the far-field projection to eliminate the predictable coupling effects of the measurement array of probes. Probe response compensation is also taken into consideration in this algorithm. EMSCAN meticulously developed this custom algorithm through comprehensive and rigorous R&D efforts to get the most accurate test results.
Most of the major smart phone manufacturers, military subcontractors, antenna manufacturers, consumer electronics manufacturers and universities have added RFxpert to their test facilities.