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Cost-effective Wireless Antenna Measurement Systems
Two new antenna measurement systems have recently been introduced that add to the MI-3600 antenna measurement product line. The MI-3600 family is comprised of 20 antenna measurement systems for single- or dual-axis antenna pattern measurements in the popular wireless frequency ranges. The systems have extensive built-in analysis software to simplify pattern evaluation and provide pattern plotting in polar or rectangular format for single or multiple patterns. The MI-3600 family is one of the most cost-effective and affordable antenna test and measurement products currently on the market.
The MI-3614 system is a mid-range, single-axis far-field measurement system designed for wireless applications. It is a complete instrumentation system consisting of a workstation computer and software, azimuth positioner for rotating the device-under-test (DUT), position controller, receiver, transmitter and broadband linearly polarized log periodic source antenna. Figure 1 shows the MI-3614 system configuration. The significant components are the power meter receiver, broadband synthesized source transmitter and single-axis DUT positioner. The system makes it easy to set up, select test parameters, acquire data and perform data analysis on antennas in the 100 MHz to 6 GHz frequency range in both indoor and outdoor configurations depending on option selected. The system as illustrated operates in the 500 MHz to 2.1 GHz frequency range.
Fig. 1 The MI-3614 far-field system's configuration.
Using the system workstation, the operator can select the operating frequencies from a synthesized source transmitter and record the received signal from the broadband, highly accurate power meter receiver. Various options include standard gain antennas for calibration, masts for the source antenna and DUT positioner, longer signal and control cables, and absorber.
The MI-3614 system specifications include the MI-3152 signal source operating at 100 kHz to 2.1 GHz with a 10 dBm (maximum) output power, and the MI-3221 power meter with sensor that covers 10 MHz to 18 GHz and an input power capability of -70 to +30 dBm. The MI-7122 azimuth positioner rotates ±200° with an angular accuracy of 0.5°. The MI-7111 position controller is single-axis, IEEE 488-based. The MI-3601 workstation includes software and computer, keyboard, mouse, color printer, and Ethernet and IEEE communication cards.
The analysis software is capable of performing automatic calculation of beam width, beam peak, null location and depth, sidelobe location and level, and gain. The data output formats include polar and rectangular plots. Figure 2 shows a typical rectangular far-field plot of a basestation antenna. The source is a linearly polarized, log periodic antenna that operates from 500 MHz to 12.4 GHz. The MI-3614 is a flexible test system capable of rapid, accurate and continuous far-field antenna measurements over 500 MHz to 6 GHz.
Fig. 2 A typical rectangular far-field plot of a basestation antenna.
Planar Near-field System
Fig. 3 The MI-3630's 3 x 3 scanner.
The MI-3630 system is a planar near-field measurement system comprised of a precision planar (X-Y axes) scanner, near-field probe, two-axis position controller, and workstation computer and software. The system is compatible with a number of commercially available network analyzers and receivers, and can be upgraded and tailored with numerous options to meet individual measurement needs.
The MI-3630 near-field system, shown in Figure 3 , provides accurate planar near-field measurements, and provides for near-field diagnostics and transformation to the far-field for antenna pattern evaluation. The planar surface scanner geometry is ideally suited for measuring planar arrays or reflectors with medium to high gain and single or multiple beams commonly found in wireless smart basestation antennas, point-to-point and point-to-multipoint antennas, repeater relay antennas and satellite antennas. Figure 4 shows two examples of far-field patterns obtained from near-field measurements. The system has broad frequency coverage over the 400 MHz to 8 GHz range, and models are available with a variety of planar scanner probe travel areas to suit specific test requirements for a broad array of applications.
Configurations from 3' to 10' in both X and Y axes are available. The scanner absorber is a 12" pyramidal absorber, and the probe is WR-430 open-ended waveguide with SMA transition. The probe absorber is also 12" pyramidal. The probe mount contains a bracket permitting vertical and horizontal probe mounting. Choices of RF cables, rotary joints and other options are available.
A partial list of compatible instruments includes the Agilent 8510A/ B/C, Agilent 8530A, Agilent 8753A/ B/C/D/E/ES, Anritsu MS4623B, MI Technologies' MI-1783, MI-1795 and MI-1797. The MI-3630 is a flexible, easy-to-use system that comes complete with a monitor, color printer, acquisition software and planar near-field software.
Fig. 4 Examples of far-field patterns obtained from near-field measurements.
The MI-3630 is particularly useful for testing the numerous beam patterns and modes of smart basestation antennas that are currently finding application in mobile telephony systems. Other applications include measuring higher gain panel array antennas used for highway or rural cell sites and repeaters, and base and subscriber antennas for broadband fixed wireless access such as point-to-point and point-to-multipoint systems.
MI Technologies, Duluth, GA (800) 848-7921, www.MI-Technologies.com.
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