A Calibration Method for Array Antenna using

Non-Resonant Probe

Atsushi KATSUTA1, Hiroyuki ARAI1 and Masami ARAI2 1Graduated school of engineering, Yokohama National University

79-5, Tokiwadai, Hodogaya, Yokohama, Kanagawa, 240-8501, Japan 2Huawei Technologies Japan K.K. , Japan Research Center

3-1, Kinko-cho, Kanagawa, Yokohama, Kanagawa, 221-0056, Japan

katsuta-atsushi-tc@ynu.jp

Abstract – This paper presents calibration method for array

antenna using non-resonant probe. The propose method uses measurement of electric field array antenna element using non-

resonant probe in reactive-near-field. Because the probe does not degrade the characteristics of the antenna element in reactive-near-field, this technique can measure pure electric

field using non-resonant probe. Both amplitude and phase change are measured by this method.

Index Terms — Calibration, Electric field measurement,

Electric probe, Array antenna.

1. Introduction

In recent years, as there has been an explosive increase in

wireless data traffic, high-capacity and high-speed mobile

communication is required. Therefore, multielement array

antenna is increased in demand. Accordingly, various studies

on array antenna calibration are being conducted [1][2][3].

In this paper, we study new array antenna calibration method

by measurement electric field of array antenna element using

non-resonant probe. In this method, the electric field of array

antenna element is measured in the reactive-near-field by

moving the probe closer to the measured element. In this

paper, as a fundamental study of this method, we describe

element electric field of the array antenna measurement

using an infinitesimal dipole antenna and an infinitesimal

loop antenna [4].

2. Non-Resonant Probe

Non-resonant probe is a probe that does not have

characteristic as an antenna, because it does not resonate in

a frequency band. Therefore, the effect of re-radiation of the

antenna is reduced by moving the probe closer to the

measuring antenna. This section discusses about the probe

characteristic.

(1) Characteristics of Non-Resonant Probe

The characteristic of the antenna is examined using an

infinitesimal dipole antenna and an infinitesimal loop

antenna as non-resonant probe. Fig.1 (a) shows the probe

arrangement whose positioned closer to the patch antenna in

the reactive-near-field(0.1λ). Fig.1 (b) shows the s-

parameters results for the arrangement confirming that non-

resonant probe has less impact on the patch antenna and the

coupling between patch antenna and the probe. The S11 is

very low and measured antenna’s characteristics are not

affected non-resonant probe’s characteristics.

(2) Antenna Factor of Non-Resonant Probe

The antenna factor of the probe is necessary for

measurement. Measurements of complex antenna factor by

the near field 3-antenna method is used as probe antenna

factor [5]. The probe and half-length dipole antenna is used,

complex antenna factor (F) is shown as, equation (1).

𝐹𝑖 = √𝑗𝜂0𝑒−𝑗𝛽𝑟 𝐴𝑗𝑘(𝑟)

𝑍0𝜆𝑟𝐴𝑖𝑘(𝑟)𝐴𝑗𝑖(𝑟) (1)

(𝑖, 𝑗, 𝑘 = 1,2,3, 𝑖 ≠ 𝑗 ≠ 𝑘)

Fig.2 shows the antenna factor of the probe in

measurement and calculation. Experimental values are

relatively close to simulation values. It is assumed that there

is an error due to experimental environment.

3. Element Electrical Field Measurement

We measure coupling level between the probe and each

element of the array antenna. Fig.3 shows the measurement

structure of 4×4 dipole array antenna and the probe. The

array antenna structure consists of sub arrays (SA) in which

four elements of the dipole antenna tilted by 45 degrees

arranged in four rows. Non-resonant probe is used as an

infinitesimal dipole antenna and an infinitesimal loop

antenna. Since the all result is close, I post the result only

probe 2. Where the coupling level results are shown in Fig.4

and Fig.5, respectively. The coupling level between both

probes and measured element are about 20 dB or more apart

from other element coupling level.

Fig.6 shows measurement result of probe 2, when input

signal at SA2. The input amplitude variation confirmed that

the amplitude and the phase of input signal variation

approximately equal to the amplitude and the phase of the

measurement result variation on the probe. We confirmed

that variation of the input signal amplitude and phase is equal

to variation of the measurement results amplitude and phase

on each probe 2 as shown in Fig.6. The variation

2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea

[ThP-57]

777

characteristics of loop is better than that of dipole. It is

conceivable that cause is because of the antenna

directionality.

4. Conclusion

In this paper, we propose a new calibration method for

array antenna using non-resonant probe by using a technique

of measuring the electric field of array antenna element using

non-resonant probe in reactive-near-field. We confirmed that

this technique can measure the element electric field using

non-resonant probe. Additionally, the characteristics of the

loop is better than that of the dipole, because the loop

directionality is facing the measured antenna element. Based

on this result, we design and produce a non-resonant probe

that also operate in the millimeter-wave band.

References

[1] S. Mano, et al., IEICE Trans. B., vol. J65-B, no. 5, pp. 555-560, May

1982.

[2] Y.V. Korotetskiy, et al., IEEE APM., pp.1161-1162, Jun. 2016.

[3] R. Long, et al., IEEE Trans. Elec, Vol. 65, no. 6, pp. 2931-2939, Jun.

2017.

[4] H. Whiteside, et al., IEEE Trans. Elec, Vol. 12, no.33, pp. 291-297,

May. 1964.

[5] S. Ishigami, et al., IEEE Trans. Elec, Vol. 36, no. 3, pp. 424-432,

Aug. 1996.

(a) (b)

Fig. 1 Non-resonant probe characteristics (a) structure

(b) S11 of the patch antenna.

Fig. 2 Measured and calculated antenna factor.

Fig. 3 Element E-field measurement structure.

xA = 1 λ, yA = 1 λ.

Fig. 4 Coupling level using infinitesimal dipole.

Fig. 5 Coupling level using infinitesimal loop.

(a) (b)

Fig. 6 E-field measured using each probe (a) variation

amplitude (b) variation phase of input signal.

2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea

778