NEOSCAN

non-invasive ultra-wideband electric and magnetic field measurement systems

Breakthrough turnkey field measurement system

NeoScan is an ultra-wideband, radio-frequency field measurement system that uses extremely small, non-invasive, optical-fiber-based probes for electric or magnetic field sampling. It features EMAG’s patented non-metallic electro-optic (EO) and magneto-optic (MO) probe technologies. NeoScan measurements provide a very high spatial resolution limited only by the spot size of the optical laser beam that illuminates the EO/MO crystal tip. The very small probe size and absence of any metallic parts warrant a high degree of non-invasiveness with respect to the fields at the surface of the device under test (DUT). NeoScan probes can accurately measure both the amplitude and phase of all the three components of electric or magnetic fields simultaneously.

Ultra-wideband, non-invasive, extremely-near-field probing

Conventional near-field scanning systems typically use bulky waveguide-based metallic probes that require maintaining a safe distance from the DUT to avoid perturbing its fields. Such systems are suitable for far-field antenna pattern characterization. But they can hardly be useful for diagnosing internal malfunction of microwave devices or irregularities of antenna arrays. Additionally, utilizing open-ended waveguides or horn antennas as field probes entails operational bandwidth limitations. This means different metallic probes are needed when measuring fields at different frequency bands. In contrast, NeoScan’s optical probes operate at as low as a few kilohertz and as high as tens of gigahertz. The operational bandwidth of NeoScan is limited by its output photodetectors and RF data acquisition system. Since NeoScan’s all-dielectric non-contact probes have a very small footprint, they can be placed as close as 100 microns above the surface of the DUT without causing any field disturbance.

Unique Measurement Features

  • Non-intrusive and non-contact RF measurement
  • Broad measurement bandwidth (10 MHz – 40 GHz) using the same optical probes (higher operational bandwidths or lower operational frequencies available as custom configurations)
  • Simultaneous amplitude and phase measurement
  • Vectorial component measurement with cross polarization suppression better than 20dB
  • Very wide dynamic range (> 70 dB) measuring very low field intensities under 1 V/m to extremely high field intensities above 2 MV/m using the same optical probes
  • Typical probe tip size: 1 mm3 (smaller footprints available as custom configurations)
  • High spatial resolution with scan steps as small as 100 μm or less
  • DUT proximity as close as 100 μm
  • Standoff distance (between field probe and mainframe box) up to 50 m

How does NeoScan work?

NeoScan’s principle of operation relies on the polarization state modulation of an optical beam due to the presence of an impressed electric or magnetic field inside certain optical crystals. When an optical beam propagates through an electro-optic (EO) crystal, it experiences a linear birefringence effect, also known as the Pockels effect. The ordinary and extraordinary propagating modes inside the EO crystal travel with different phase velocities, resulting in a rotation of the polarization state of the incident beam. The amount of rotation is linearly proportional to the magnitude of the impinging electric field. In a similar manner, when an optical beam propagates inside a magneto-optic (MO) crystal, its polarization state rotates by an amount that is linearly proportional to the magnitude of the magnetic flux density present in the crystal and aligned along its optical axis. This is known as the Faraday effect. Through precise synchronization of the optical and RF signal generation and processing utilities, NeoScan is able to measure the relative phase of the DUT’s field. A comparison of the polarization states of the optical beam before and after interacting with the EO/MO crystal allows an accurate determination of the amplitude and phase of the present electric or magnetic field at the probe location.

NeoScan system architecture & configurations

Every NeoScan system consists of a laser source and an optical bench that takes the laser beam at its input port and delivers it to a crystal-based field probe via a long segment of polarization-maintaining (PM) optical fiber. At the output port of the optical bench there is a high-speed, high-frequency photodetector that converts the input optical signal to an RF electric signal. The output RF signal is amplified and processed to determine the amplitude and phase of the field component picked up by the probe. The simplest NeoScan system is configured as single-channel to measure the amplitude and phase of a single field component at a time. NeoScan systems with two or more coherent channels can be configured, e.g., to measure all the three electric field components simultaneously and coherently.

Frequency-domain near-field scanning mode

When the field probes are mounted on a computer-controlled precision moving stage, you can scan the surface of the device under test (DUT) using NeoScan and generate high-resolution field distribution maps. This operational mode of NeoScan is called frequency-domain near-field scanning. In this mode, NeoScan’s output signal is down-converted to a low frequency, e.g., 100 MHz, where the amplitude and phase of the input complex-valued signal are measured using a lock-in amplifier. The field maps can be used for fault detection or diagnostic purposes. When the DUT is an antenna, NeoScan performs a near-to-far-field transformation of the map to estimate the far-field radiation pattern of the antenna under test (AUT).

Real-time waveform tracking mode

In a different operational mode called real-time waveform tracking, the field probe is fixed at a certain location, and NeoScan’s output signal is sampled and digitized to detect and track the field waveform as a function of time at the probe location. A high-speed, high-frequency, digital sampling oscilloscope can be used for data acquisition in this mode. If the DUT field has a band-limited non-harmonic waveform other than a single-tone sinusoid, that waveform is still preserved and detected at the output of the photodetector. This mode of NeoScan can be very useful to measure and characterize signal integrity and crosstalk in digital circuits. Neoscan’s non-contact optical field probes can effectively be utilized as infinite-impedance voltage and current probes.

What can NeoScan do?

Antenna Characterization

The far-field radiation pattern of microwave antennas is typically characterized in an anechoic chamber environment. The receiving antenna must be placed in the transmitting antenna’s far-field region to ensure measurement accuracy. Conventional near-field ranges relax this spatial separation requirement considerably. Using NeoScan probes, you can go much closer to the surface of the antenna under test (AUT) without perturbing its radiating fields. The optical probes only pick up the near-zone fields and are not affected by the multipath EMI/RFI in the environment. This means no need for a large anechoic chamber covered with expensive abosrber foam materials. EMAG’s EM.Cube software, which is integrated with the NeoScan system, automatically performs a near-to-far-field transformation of the tangential near-field maps to compute the full 3D far-field radiation pattern of the AUT. In the very close proximity of the AUT’s surface, evanescent reactive fields are present – they do not propagate into the far-field zone. You can increase the distance of the NeoScan probe from the aperture to avoid such highly oscillatory fields and benefit from a coarser sampling grid, thus reducing the measurement time.

RF Diagnostics

RF engineers are used to work with oscilloscopes, network analyzers and spectrum analyzers all the time. These instruments perform port-based measurements. They do not shed light on the internal operation of the device under test (DUT). It takes an experienced engineer to correlate the port-based measurement data with the possible root cause of a failure or malfunction in an RF circuit. NeoScan’s very-near-field maps reveal the physical behavior of RF devices and systems, offering valuable insight that cannot be captured by indirect methodologies. External port-based measurements are inadequate in characterizing how signals, fields and waves originate, evolve, and propagate inside your device from port to port or out into the free space. NeoScan can help you identify hot spots of your circuit, where electromagnetic coupling, crosstalk, leakage, oscillations or unwanted emissions from a device’s package might degrade the performance of the DUT.

EMC/EMI Testing

The rapid proliferation of RF devices everywhere from our phones, headsets, watches and medical implants to electric cars and autonomous vehicles, underlines a persistent need for electromagnetic compatibility (EMC) testing and accurate quantification of electromagnetic interference (EMI) among proximate devices and systems. Conventional EMC test procedures such as CISPR 25 are typically performed in expensive anechoic or electromagnetic reverberation chambers. The NeoScan system offers a relatively low-cost alternative to those costly methodologies. It can measure weak emitted electric field intensities down to 1 V/m and lower in an ordinary laboratory environment. Scanned near-field maps of emitting devices can also reveal valuable information about their radiation, coupling and leakage mechanisms.

Biological Measurements & Dosimetry

Electromagnetic waves and RF energy are utilized in several therapeutic medical procedures for treatment of breast cancer, neurological disorders, and other diseases. Measuring field penetration and distribution in in-vivo saline environments and physiological organs can help improve the efficacy of such procedures and also monitor the progress of a treatment. To this end, miniaturized field probes are needed to avoid damaging the host biological tissue. NeoScan probes feature very small footprints that keep shrinking (currently down to a few hundred microns) through our continuous research and development. Contemporary methodologies such as specific absorption rate (SAR) simulations offer an incomplete image of how electric fields propagate and interact with biological systems. In a recent collaboration between EMAG and New York University (NYU) Neuroscience Institute, a proof-of-concept methodology was demonstrated through direct measurement of stimulated electric fields inside the brain of live rodent subjects under anesthesia.

Additional applications of the NeoScan system include:

  • Active phased array calibration
  • Electromagnetic model and RF design verification and validation (V&V)
  • Real-time field sniffing and detection
  • High-power microwave system test and evaluation
  • Non-contact and non-destructive evaluation in industrial systems

A selection of recent NeoScan-related technical papers

A selection of technical publications featuring NeoScan

O. Yaghmazadeh, S. Schoenhardt, A. Sarabandi, A. Sabet, K. Sabet, F. Safari, L. Alon, and G. Buzsáki, “In-vivo Measurement of Radio Frequency Electric Fields in Mice Brain,” to be published in Biosensors and Bioelectronics, vol 13, May 2023.
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M. Rao and K. Sarabandi, “A Near-Field-Based Gain and Pattern Measurement Technique for Probe-Fed Millimeter-Wave Antennas,” IEEE Antennas and Propagation Magazine, vol. 64, no. 65, pp. 91 – 100, 6 Dec, 2022.
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M. Rao and K. Sarabandi, “A Low-Profile Dual-Band Dual-Polarized Quasi-Endfire Phased Array for mmWave 5G Smartphones,” IIEEE Acces, vol. 10, pp. 38523-38533, 7 Apr. 2022.
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Amjadi, M. Rao and K. Sarabandi, “Wideband Near-Zone Radiative System for Exploring the Existence of Electromagnetic Emission from Biological Samples,” IEEE Transactions on Instrumentation and Measurement,” vol. 69, no. 10, pp. 8344 – 8351, October 2020
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C. Deng, D. Liu, B. Yektakhab and K. Sarabandi, “Series-Fed Beam-Steerable Millimeter-Wave Antenna Design With Wide Spatial Coverage for 5G Mobile Terminals,” IEEE Trans. Antennas & Propagat., vol. 68, no. 5, pp. 3366–3376, May 2020.
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W. Dykeman, B. Marshall, D. Canterbury, C. Garner, R. Darragh, A. Sabet, “Comparison of Antenna Measurements Obtained Using an Electro-Optical Probe System to Conventional RF Methods,” Antenna Measurement Techniques Association Symposium (AMTA), San Diego, CA, 6-11 Oct. 2019.
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Urbonas, K. Kim, F. Vanaverbeke, and P. H. Aaen, “An electro-optic pulsed NVNA load-pull system for distributed E-field measurements,” IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 6, pp. 2896-2903, June 2018
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K. Sabet, R.Darragh, A. Sabet, K. Sarabandi and L. Katehi, “Using Electro-Optic Field Mapping for Design of Dual-Band Circularly Polarized Active Phased Arrays,” IEEE 18th Wireless and Microwave Technology Conference (WAMICON). Cocoa Beach, FL, Apr. 24-25, 2017.
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K. Sarabandi, J. Choi, A. Sabet and K. Sabet, “Pattern and gain characterization using nonintrusive very-near-field electro-optical measurements over arbitrary closed surfaces,” IEEE Trans. Antennas & Propagat., vol. 65, no. 2, pp. 489-497, Feb. 2017.
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Sabet, R. Darragh, A. Sabet, K. Sarabandi, K. Jamil and S. Alhumaidi, “Characterization and diagnostics of active phased array modules using non-invasive electro-optic field probes with a CW laser source,” IEEE International Microwave Symposium, Honolulu, HI, Jun. 5-9, 2017.
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K. Yang, T. Marshall, M. Forman, J. Hubert, L. Mirth, Z. Popovic, L.P. B. Katehi and J.F. Whitaker, “Active-amplifier-array diagnostics using high-resolution electrooptic field mapping,” IEEE Trans. Microwave Theory Tech., vol. 49, no. 5, pp. 849-857, May 2001.

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K. Yang, G. David, J-G Yook, I. Papapolymerou, L.P. B. Katehi and J.F. Whitaker, “Electrooptic mapping and finite-element modeling of the near-field pattern of a microstrip patch antenna,” IEEE Trans. Microwave Theory Tech., vol. 48, no. 2, pp. 288-294, Feb. 2000.
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K. Yang, G. David, S.V. Robertson, J.F. Whitaker and L.P. B. Katehi, “Electrooptic mapping of near-field distributions in integrated microwave circuits,” IEEE Trans. Microwave Theory Tech., vol. 46, no. 12, pp. 288-294, Dec. 1998
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Built to your exact needs

EMAG Technologies Inc. offers a wide range of RF field probes, detection sensors and near-field scanning systems for direct measurement of electric and magnetic fields. Our products reflect the state of the art in electro-optic and magneto-optic field sampling technologies. Our turnkey NeoScan system provides complete measurement solutions including the optical mainframe and probes, supporting electronics, precision translation stages of various sizes, control software, and postprocessing tools for measured field data. Our systems are customized to meet your particular measurement needs with regards to sensitivity, spatial resolution, instantaneous bandwidth, test medium, ruggedized packaging requirements, etc.

Customization means endless possibilities

Our standard turnkey NeoScan system has an operational bandwidth of 10 MHz – 40 GHz. We can build custom NeoScan systems operating at higher frequency bands up to 100 GHz or go to lower frequency bands down to 1 kHz. Many applications like antenna characterization require simultaneous measurement of two or more field components. We can build multi-channel NeoScan systems with any number of fully coherent independent channels. Large numbers of coherent channels can be realized and integrated within the same NeoScan system using a combination of optical and RF multiplexing.

3D Near-Field Scanning

It is possible to customize the NeoScan system for characterization of 3D nonplanar antennas. Using a computer-controlled rotational stage combined with a three-axis XYZ translation stage, we can customize NeoScan for cylindrical near-field scanning. Cubic near-field scanning can also be accomplished using the concept of Huygens surface. In that case, the amplitude and phase of the two tangential electric field components on each of the six faces of a Huygens cube enclosing the AUT must be scanned. A three-dimensional near-to-far-field transformation of the resulting six complex-valued field maps produces the 3D far-field radiation pattern of the AUT.

Our standard turnkey NeoScan system has an operational bandwidth of 10 MHz – 40 GHz. We can build custom NeoScan systems operating at higher frequency bands up to 100 GHz or go to lower frequency bands down to 10 kHz. Many applications like antenna characterization require simultaneous measurement of two or more field components. We can build multi-channel NeoScan systems with any number of fully coherent independent channels. Large numbers of coherent channels can be realized and integrated within the same NeoScan system using a combination of optical and RF multiplexing. It is also possible to customize NeoScan system for characterization of 3D nonplanar antennas. Using a computer-controlled rotational stage combined with a three-axis XYZ translation stage, we can customize NeoScan for cylindrical near-field scanning. Cubic near-field scanning can also be accomplished using the concept of Huygens surfaces. In that case, the amplitude and phase of the two tangential electric field components on each of the six faces of a Huygens cube enclosing the AUT must be scanned. A three-dimensional near-to-far-field transformation of the resulting twelve complex-valued field map produces the 3D far-field radiation pattern of the AUT.

Let’s talk about your measurement needs

Contact us today to discuss your antenna and RF field measurement requirements. Our engineers will recommend a system configuration that will best suit your measurement needs and budget. EMAG Technologies offers special academic discounts for educational use of NeoScan systems.

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