NF2FF

Near-Field to Far-Field Transformation for Antenna Measurements

Description

Near-Field to Far-Field Transformation for Antenna Measurements (NF2FF).

Hologram analysis can also be used to study near field communication (NFC) antennas.

J. Logan ([e-mail])
A. P. Mynster ([e-mail])
M. J. Pelk ([e-mail])
C. Ponder ([e-mail])
K. Van Caekenberghe ([e-mail])

The script assumes:
1. Rectangular coordinate system with z axis normal to planar aperture
2. exp(j*omega*t) time dependence convention. Please, substitute i with -j whenever implementing exp(-i*omega*t) time dependence convention based algorithms.

The script uses:
1. Near field datasets of a 94 GHz slotted waveguide (U.S. Patent No.: 7,994,969) can be downloaded from: http://www-personal.umich.edu/~vcaeken/DATASETS.zip.

Sought-after extensions are listed below. Please post them on the
website, if you are willing to contribute:
1. Cylindrical and spherical near field to far field transformation
2. Graphical user interface

The package also includes data acquisition scripts for reading out S-parameters from the HP 8510C and HP 8720ES network analyzers, and the Rohde & Schwarz ZVA40 network analyzer. The DAQ scripts require a MATLAB Instrument Control Toolbox license.

References:
1. C. A. Balanis, "Antenna Theory, Analysis and Design, 2nd Ed.", Wiley, 1997. [exp(j*omega*t) time dependence convention]
2. D. Paris, W. Leach, Jr., E. Joy, "Basic Theory of Probe-Compensated Near-Field Measurements", IEEE Transactions on Antennas and Propagation, Vol. 26, No. 3, May 1978. [exp(-i*omega*t) time dependence convention]
3. A. D. Yaghjian, "Approximate Formulas for the Far Field and Gain of Open-Ended Rectangular Waveguide", IEEE Transactions on Antennas and Propagation, Vol. 32, No. 4, April 1984. [exp(-i*omega*t) time dependence convention]
4. A. D. Yaghjian, "An Overview of Near-Field Antenna Measurements", IEEE Transactions on Antennas and Propagation, Vol. 34, No. 1, June 1986. [exp(-i*omega*t) time dependence convention]
5. G. F. Masters, "Probe-Correction Coefficients Derived From Near-Field Measurements", AMTA Conference, October 7-11, 1991.
6. J. J. Lee, E. M. Ferren, D. P. Woollen, and K. M. Lee, "Near-Field Probe Used as a Diagnostic Tool to Locate Defective Elements in an Array Antenna", IEEE Transactions on Antennas and Propagation, Vol. 36, No. 6, June 1988. [exp(-i*omega*t) time dependence convention]
7. http://www.fftw.org/
8. R. M. Goldstein, H. A. Zebken, and C. L. Werner, "Satellite Radar Interferometry: Two-Dimensional Phase Unwrapping", Radio Sci., Vol. 23, No. 4, pp. 713-720, 1988.
9. D. C. Ghiglia and M. D. Pritt, "Two-Dimensional Phase Unwrapping: Theory, Algorithms and Software". Wiley-Interscience, 1998.
10. J. M. De Freitas. "SPHERE3D: A Matlab Function to Plot 3-Dimensional Data on a Spherical Surface".
   QinetiQ Ltd, Winfrith Technology Centre, Winfrith,
   Dorchester DT2 8XJ. UK. 15 September 2005.
10. http://nf2ff.sourceforge.net

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
3D Plot on a Spherical Surface, 2D phase unwrapping algorithms, HP 8510C Demo

• MATLAB release: MATLAB 7.7 (R2008b)

[John]

I came across this file when trying to explore my own ways of processing planar near-field data that I had already measured for my senior project. When exploring the topic of near-field to far-field transformation, I found various methods on how to complete the task of producing a far-field pattern from near-field measurements, such as multiple unclear ways on how to produce an angular map of the transformed data.
 
This is when I stumbled upon this file. NF2FF is a great and clear resource for understanding the near-field to far-field transformation process. The program goes above and beyond characterizing the far-field pattern, as it actually takes the user through a step-by-step processing of data and plotting from start to finish.

I would have to say it does require you to have extensive knowledge on the actual background of what you need to do, or you won't have a clue as to why certain things are being done (which isn't a bad thing). Also, the only aspect that may be somewhat confusing is the input process, but if you've come this far you probably already have an idea of what your own parameters are and how to work with them.

What I truly found amazing was the willingness of the author, Koen Van Caekenberghe, to provide assistance and advice. From my own experience, I had major trouble with taking the far-field spectral domain and applying an angular mapping technique to compare with my anechoic chamber data. Once Koen helped me, I found that his program is extremely accurate with planar near-field data processing up to around +-40 degrees. With probe compensation, this could be vastly improved out to +-75 degrees.

  
 

[Chris]

I would like to say that this file is absolutely brilliant and the help and support I recived from the author beyond anything I could have hoped for.