Antenna Test Systems Evolve to Commercial-Off-the-Shelf Products Near-Field Test Methods Drive Faster Test Times and Economical Production

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August 2010

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Fully Matched Cascadable Amp
The TQP3M9009 has been added to the company’s low noise gain block family for high performance 3G/4G infrastructure. This cascadable amplifier is fully matched internally, allowing designers to focus on system level needs. It operates over a broad .05 to 4 GHz frequency range.

Bandpass Filter
Part number 2965-SMA is a 500 MHz bandpass filter. The filter has a typical 1 dB bandwidth of 8 MHz, insertion loss of 6.5 dB and typical 40 dB bandwidth of 52 MHz. It is supplied in a 0.6 x 0.6 x 2.25" SMA package and may be customized for other center frequencies and bandwidths.

UltraFast™ Digitally Programmable LDO
The LT3071 is the second in a family of digitally programmable linear regulators with the lowest dropout voltage, lowest noise, and fastest transient response of any monolithic 5A LDO currently available. Dropout voltage at 5A is an ultralow 85mV. Its QFN package is 4 x 5 x 0.75mm in size.

Microwave Power MMIC
A 4W C-Band GaAs MMIC for satellite applications, the TMD0608-4 operates in the 5.65 to 8.50 GHz range. With this broad bandwidth, a high gain of 27 dB throughout the operating range, and 50 ohm internal matching, this device is well suited for use as a pre-amplifier in C-Band satellite and terrestrial communications.

USB Power Sensors
The U2000 Series USB-based power sensors are compact, portable solutions that allow average power measurements without power meters. All sensors, except the U2004A model, feature internal triggering and trace display capabilities. Current users of these sensors can upgrade their firmware for free.

Directional Couplers
Miniature air dielectric directional couplers are rugged, lightweight devices that offer lower insertion loss than comparable stripline units. The simplified construction allows for greater flexibility in creating customized configurations. Any port can be used as the input with these devices.

Elliptic Lowpass Filter
Part number 2969-SMA is a high order 10 MHz elliptic lowpass filter with sharp transition to the stopband and high stopband attenuation. Typical 1 dB bandwidth is 10.9 MHz with minimum 84 dB attenuation at 13.125 MHz. It is supplied in a 0.6 x 0.6 2.25" package with SMA connectors.

Directional Coupler
Model 110067016 directional coupler has a frequency range of 10 to 67 GHz, 7.25 directivity, and maximum VSWR (any port) of 2.0. Coupling (with respect to output) is 16 +/-1.1 dB and frequency sensitivity is +/-2.0 dB. Operating temperature range is -54 to +85ºC.

Fixed Frequency Synthesizer
The SFS6400A-LF in C-band is a single frequency synthesizer that operates at 6400 MHz. This synthesizer features a typical phase noise of -88 dBc/Hz @ 10 KHz offset and typical sideband spurs of -65 dBc. Its PLL-V12N package measures only 0.60 x 0.60 x 0.13".

Higher Power GaAs FETs
The company has expanded its Ku-Band GaAs FET lineup with two higher output power devices rated for 18 and 30W. Models TIM1213-18L and TIM1213-30L operate in the 12.7 to 13.2 GHz range and are targeted for use in microwave radios for microwave links and satellite communications.

EMT SMT Diode TVS Connectors
Now available are transient protection solutions embedded within the connector shell utilizing surface mount (SMT) diodes. Using SMT diode technology allows for increased flexibility in the packaging of transient protection within the connector, saving both space and weight.

Low Noise Gain Block
Model TQP3M9008 is a new low noise gain block that offers high gain over a broad .05 to 4 GHz frequency range. It is a cascadable amplifier that requires no external matching components and can reduce BOMs. The gain block provides 35.5 dBm OIP3, while maintaining a low 1.3 dB noise figure.

October 2009

Antenna Test Systems Evolve to Commercial-Off-the-Shelf Products
Near-Field Test Methods Drive Faster Test Times and Economical Production
By Daniël Janse van Rensburg, Sales & Marketing Manager,
Nearfield Systems Inc.

The microwave antenna test industry has, over the last decade, seen the introduction of Commercial-Off-the-Shelf [COTS] test systems that allow manufacturers to approach antenna testing in much the same way as benchtop network analysis. The subsequent savings in time and efficient use of facilities is helping to drive down the cost of production and improve quality for a wide range of microwave antenna applications.

This wasn’t always the case. The antenna test industry initially focused on outdoor Far-Field testing, where the source and receiver were separated by a sufficiently large distance such that the radius of curvature of the wave front hitting the antenna under test appears to be locally flat. For electrically large antennas (that is, antenna dimensions large in terms of wavelengths), this distance can become prohibitively large. This space limitation, in addition to other factors like exposure of the test article to the elements and the fact that the purity of the plane wave illuminating the antenna can be greatly compromised by reflections from surrounding structures, lead to the desirability of indoor testing and subsequent development of alternative test methods.

Near-Field Testing Provides the Solution
Using Near-Field techniques, antennas can be characterized through testing in very close proximity to the device in an environmentally stable anechoic chamber and then, relying on mathematical transformation, the desired Far-Field radiation characteristics may be obtained.

Near-Field techniques allow for very efficient use of space and lower cost anechoic environments compared to outdoor Far-Field testing. In addition, the introduction of modern automated network analyzers provide for highly accurate and readily available RF subsystems. This has allowed antenna testing to become an integral part of the production process rather than an expensive field exercise.

Today, Near-Field scanning hardware is integrated with these RF subsystems through software, making Near-Field antenna test systems easily accessible COTS tools. Many turn-key Near-Field test systems can be installed in as little as eight hours, allowing engineers to obtain highly accurate antenna test characteristics within minutes after installation.

Looking to the very near future, new planar and spherical scanners combined with vector network analyzers make high speed, multi-frequency antenna testing commonplace. In the case of planar Near-Field scanners, testing within an office environment is feasible.

Near-Field test and measurement techniques, combined with COTS analyzers and components, will continue to reduce the cost and improve the efficiency of microwave antenna testing for years to come. For more information, visit www.nearfield.com

Nearfield Systems Inc.
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