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Abstract—In this paper a compact radiation pattern
measurement setup at 240 GHz is investigated. It consists on a
millimeter-wave source as transmitter (Tx) and a Schottky diode
as receiver (Rx). Three different horn antennas fabricated with
different fabrication techniques are presented: Stereolithography
Apparatus (A
2
), Selective Laser Sintering (A
3
) and commercial
metallic (A
1
). Radiation patterns are discussed and compared, as
well as dynamic range. A good agreement between simulation
and measurement results was obtained.
I. INTRODUCTION
N order to meet the growth of data traffic in wireless
transmissions, it is necessary to develop both active devices
(RF mixer, amplifier) and passive devices (diodes, antennas)
or sub-systems that work in mmw (millimeter-wave) to
increase the capacity of wireless links [1].
Antenna design, fabrication and measurement at mmw
frequencies is an important challenge for many mmw/sub-
mmw systems, and particularly for wireless communications
systems. Therefore, in recent years, several three-dimensional
(3D) printing technologies for antennas production have been
developed in order to simplify the manufacturing process,
reduce cost and achieve good efficiency antennas [2].
In this context, some antenna measurement systems have
been investigated [3] seeking greater accuracy and dynamic
range. Most setups use a VNA (vector network analyzer) in
radiation pattern measurement for its high sensitivity, however
the mechanical setup can be quite complex, at least more
complex than using a spectrum analyzer in Rx [4]–[6].
We propose to investigate the use of a mmw-source
combined with a synchronous detection associated with
Schottky diodes to reduce the complexity of the measurement
setup and achieve higher cost efficiency.
Three different antennas were analyzed in order to validate
the measurement setup. The measurement antenna A
1
is a
commercial horn antenna. The two other antennas are the
devices under test. A
2
is a corrugated horn antenna produced
by stereolithography apparatus (SLA) and A
3
is a corrugated
horn antenna produced by selective laser sintering.
II. GAIN MEASUREMENT
The gain measurement in the antenna main direction of
radiation was done using a VNA in WR3.4 band, mmw
transmit/receive (T/R) modules and a known gain antenna
(Figure 2).
The following gains at 240 GHz were obtained:
A
1
≅ 22 dBi, A
2
≅11 dBi and A
3
≅ 9 dBi. A
1
has the highest
gain (full metallic structure and best conductivity/roughness),
lowest gain is obtained with A
3
antenna (which has a rough
surface, which affects the gain).
III. ANTENNA PATTERN MEASUREMENT SETUP AND ITS
DYNAMIC RANGE
The measurement system is composed of a multiplication
chain (WR3.4 band), radiating in free space, and receiver is a
Schottky diode moving on a sphere. The signal is amplitude
modulated at low frequency, and a lock-in technique is used to
retrieve the modulated signal at reception.
The aperture sizes of measuring antenna and the antennas
under test (AUT) are approximatively A
1
= 6.5 mm,
A
2
= 1 mm, and A
3
= 1 mm. For characterization of an AUT
using the far-field (FF) techniques, we must check if the FF
condition (R
ff
= 2D
2
/λ) is respected for all the AUT (in this
case, for 240 GHz, 90 mm). All measurements were done
using a distance R > 200 mm.
We decided to use A
2
for a validation between the
simulations and measurements at 240 GHz (the exact internal
dimensions of the commercial horn A
1
were not known). The
simulation of the radiation pattern was done using HFSS
software [7] and H and E planes are shown in figure 3.
C. Belem Goncalves
1,2,3
, E. Lacombe
1,2
, Carlos del Río
4
, F. Gianesello
1
, C. Luxey
2
, G. Ducournau
3
1
STMicroelectronics, Crolles, 38920 France
2
Laboratory of Polytech Nice-Sophia, Univ. Nice Sophia-Antipolis, Sophia Antipolis, 06903 France
3
Institute of Electronics, Microelectronics and Nanotechnology, Villeneuve d’Ascq, 59652 France
4
Electrical and Electronic Engineering Department, Public University of Navarre, Pamplona,
31006 Spain
Compact antennas pattern measurement setup at 240 GHz
I
Fig. 1. WR3.4 (220-325 GHz waveguide feed) Antennas A
1
, A
2
, A
3
use
d
for bench measurement validation.
Fig. 2. Measured gain for A1, A2 and A3.
978-1-5386-3809-5/18/$31.00 ©2018 IEEE
The difference between simulations and measurement is
less than 2 dB for all points. The radiation patterns are also in
good agreement on H and E planes at 240 GHz, so we can
conclude that SLA is an efficient and good technique for 3D
printed antennas in WR3.4 band.
The theoretical dynamic range of the measurement setup
was calculated using (1).
(1)
In (1), the Rx sensitivity (
) ≅
-62 dBm, input power of
AUT (
) ≅ 0 dBm,
is the AUT gain, measurement
antenna gain (
) ≅ 24 dBi and free-space loss
factor (
)
≅ 69 dB to 300 mm distance between AUT and
A
meas
. Therefore, the theoretical dynamic range for each setup
is A
1
≅ 41 dB, A
2
≅ 27 dB, and A
3
≅ 25 dB.
Figure 4 shows the radiation pattern of the antennas. A
1
is
more directive than the other two, which was expected
because its manufacturing process is more sophisticated. The
rough surface in A
3
is reducing its efficiency.
Taking into account the observed dynamic ranges of the
figure 4, theoretical dynamic range is in very good agreement
with measurements.
IV. CONCLUSIONS
In this paper, a new compact measurement setup has been
presented using a multiplication chain and schottky receiver.
It is able to measure radiation pattern along spherical
surfaces around an AUT. A first validation of the system
comparing simulations with the measurements at 240 GHz
has been used to validate the system, with encouraging results.
Three antennas were measured and, as expected, A
1
has
the best performance in gain and directivity, but also has a
high manufacturing cost. For this reason, other
implementation techniques are analyzed, and SLA showed
better results when compared with metallic 3D printing.
This work has been supported by IEMN-ST common
laboratory. Part of the experimental work was also supported
by funding from Horizon 2020, the European Union’s
Framework Programme for Research and Innovation, under
grant agreement No. 814523. ThoR has also received funding
from the National Institute of Information and
Communications Technology in Japan (NICT).
REFERENCES
[1] T. Nagatsuma, G. Ducournau, and C. C. Renaud, “Advances in terahertz
communications accelerated by photonics,” Nat. Photonics, vol. 10, no. 6, pp.
371–379, 2016.
[2] B. ZHANG, Y.-X. GUO, H. ZIRATH, and Y. P. ZHANG, “Investigation
on 3-D-Printing Technologies for Millimeter- Wave and Terahertz
Applications,” Proc. IEEE, vol. 105, no. 4, pp. 723–736, 2017.
[3] D. GULAN, Heiko, LUXEY, Cyril, TITZ, Handbook of Antenna
Technologies. 2014.
[4] L. Boehm, F. Boegelsack, M. Hitzler, and C. Waldschmidt, “An automated
millimeter-wave antenna measurement setup using a robotic arm,” IEEE
Antennas Propag. Soc. AP-S Int. Symp., vol. 2015–Octob, pp. 2109–2110, 20
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[5] D. Novotny, J. Gordon, J. Coder, M. Francis, and J. Guerrieri,
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[6] D. Hou, Y. Z. Xiong, W. L. Goh, S. Hu, W. Hong, and M. Madihian,
“130-GHz on-chip meander slot antennas with stacked dielectric resonators in
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pp. 4102–4109, 2012.
[7] https://www.ansys.com/products/electronics/ansys-hfss
Fig. 3. A2 radiation pattern simulated and measured at 240 GHz.
Fig. 4. Radiation pattern measured at 240 GHz of antennas A1, A2 and A3.
Patterns where normalized to the antenna A
1
.
