### Abstract

While complex planar near-field measurements involve a formal sampling step requirement (less than 0.5λ, typically 0.45λ) phaseless planar near-field measurements with the two-scans technique do not. In phaseless measurements only the magnitude is measured; while the plane wave spectrum of the square of the magnitude has twice the bandwidth of the complex signal, the magnitude itself may have an even much larger bandwidth. However, the spectrum of the magnitude is not of significance for phaseless measurements with the two-scans technique where the measured magnitude is combined with an initial guess for the phase to form a complex signal. But this combined complex field may also have a plane wave spectrum that is broader than that of the measured complex signal and thus extend beyond the visible region of the spectral domain. This will happen if the initial guess for the phase does not fit properly to the measured magnitude; e.g. if the phase jumps by 180deg. at a point where the measured magnitude in non-zero. For this reason, the phaseless measurement may require a sampling step notably smaller than λ/2 to avoid aliasing effects in the visible region of the spectral domain. This work, based on experimental and simulated planar near-field measurements of a 60GHz horn, investigates the effect of the initial guess for the phase on the plane wave spectrum of the combined complex signal. Furthermore, it investigates the effect of the initial guess for the phase and different sampling steps on the phase retrieval, using the Iterative Fourier Technique, and thus on the resulting far-field radiation pattern.

Original language | English |
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Title of host publication | Proceedings of 12th European Conference on Antennas and Propagation |

Publisher | IEEE |

Publication date | 1 Jan 2018 |

ISBN (Print) | 978-1-78561-815-4 |

ISBN (Electronic) | 978-1-78561-816-1 |

DOIs | |

Publication status | Published - 1 Jan 2018 |

Event | 12th European Conference on Antennas and Propagation - ExCel London, London, United Kingdom Duration: 9 Apr 2018 → 13 Apr 2018 |

### Conference

Conference | 12th European Conference on Antennas and Propagation |
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Location | ExCel London |

Country | United Kingdom |

City | London |

Period | 09/04/2018 → 13/04/2018 |

Series | IET Conference Publications |
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Volume | 741 |

### Keywords

- Magnitude-only
- Measurements
- Near-field
- Phaseless

### Cite this

*Proceedings of 12th European Conference on Antennas and Propagation*IEEE. IET Conference Publications, Vol.. 741 https://doi.org/10.1049/cp.2018.0636

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*Proceedings of 12th European Conference on Antennas and Propagation.*IEEE, IET Conference Publications, vol. 741, 12th European Conference on Antennas and Propagation, London, United Kingdom, 09/04/2018. https://doi.org/10.1049/cp.2018.0636

**A computational and experimental investigation of λ/2 and λ/4 sampling step in phaseless planar near-field measurements at 60GHz.** / Álvarez, Javier Fernández; Breinbjerg, Olav.

Research output: Chapter in Book/Report/Conference proceeding › Article in proceedings › Research › peer-review

TY - GEN

T1 - A computational and experimental investigation of λ/2 and λ/4 sampling step in phaseless planar near-field measurements at 60GHz

AU - Álvarez, Javier Fernández

AU - Breinbjerg, Olav

PY - 2018/1/1

Y1 - 2018/1/1

N2 - While complex planar near-field measurements involve a formal sampling step requirement (less than 0.5λ, typically 0.45λ) phaseless planar near-field measurements with the two-scans technique do not. In phaseless measurements only the magnitude is measured; while the plane wave spectrum of the square of the magnitude has twice the bandwidth of the complex signal, the magnitude itself may have an even much larger bandwidth. However, the spectrum of the magnitude is not of significance for phaseless measurements with the two-scans technique where the measured magnitude is combined with an initial guess for the phase to form a complex signal. But this combined complex field may also have a plane wave spectrum that is broader than that of the measured complex signal and thus extend beyond the visible region of the spectral domain. This will happen if the initial guess for the phase does not fit properly to the measured magnitude; e.g. if the phase jumps by 180deg. at a point where the measured magnitude in non-zero. For this reason, the phaseless measurement may require a sampling step notably smaller than λ/2 to avoid aliasing effects in the visible region of the spectral domain. This work, based on experimental and simulated planar near-field measurements of a 60GHz horn, investigates the effect of the initial guess for the phase on the plane wave spectrum of the combined complex signal. Furthermore, it investigates the effect of the initial guess for the phase and different sampling steps on the phase retrieval, using the Iterative Fourier Technique, and thus on the resulting far-field radiation pattern.

AB - While complex planar near-field measurements involve a formal sampling step requirement (less than 0.5λ, typically 0.45λ) phaseless planar near-field measurements with the two-scans technique do not. In phaseless measurements only the magnitude is measured; while the plane wave spectrum of the square of the magnitude has twice the bandwidth of the complex signal, the magnitude itself may have an even much larger bandwidth. However, the spectrum of the magnitude is not of significance for phaseless measurements with the two-scans technique where the measured magnitude is combined with an initial guess for the phase to form a complex signal. But this combined complex field may also have a plane wave spectrum that is broader than that of the measured complex signal and thus extend beyond the visible region of the spectral domain. This will happen if the initial guess for the phase does not fit properly to the measured magnitude; e.g. if the phase jumps by 180deg. at a point where the measured magnitude in non-zero. For this reason, the phaseless measurement may require a sampling step notably smaller than λ/2 to avoid aliasing effects in the visible region of the spectral domain. This work, based on experimental and simulated planar near-field measurements of a 60GHz horn, investigates the effect of the initial guess for the phase on the plane wave spectrum of the combined complex signal. Furthermore, it investigates the effect of the initial guess for the phase and different sampling steps on the phase retrieval, using the Iterative Fourier Technique, and thus on the resulting far-field radiation pattern.

KW - Magnitude-only

KW - Measurements

KW - Near-field

KW - Phaseless

U2 - 10.1049/cp.2018.0636

DO - 10.1049/cp.2018.0636

M3 - Article in proceedings

SN - 978-1-78561-815-4

BT - Proceedings of 12th European Conference on Antennas and Propagation

PB - IEEE

ER -