IEEE - Aerospace and Electronic Systems - February 2022 - 41

Lei et al.
Figure 15.
Satellite of Inmarsat-5 (GX 1, 2, 3, 4) (left) [23] and Inmarsat-5
(GX 5) (right) [24].
Figure 17.
" Medusa " Rx MFPB EM feed cluster [26].
Figure 16.
Express-AMU1 satellite [27] and measured directivity on Kaband
multibeam coverage [4].
all the globe. And the satellite in Figure 15 left showed
that 2 Rx and 1 Tx multibeam antenna reflectors in one
back shelf is installed on one sides of the satellite deck.
The other side of the deck has the same formation of
reflectors installed in one back shelf. And Inmarsat booked
a fourth satellite GX 4 as a spare later.
The fifth satellite in the Global Xpress fleet, GX 5 [24]
from Thales Alenia Space, launched on November 26,
2019 to provide services across Europe and the Middle
East, is a very high throughput satellite (V-HTS). GX 5
delivered more capacity than the whole GX 1-GX 4 combined.
And 2 Tx and 4 Rx multibeam antenna reflectors in
the SFPB method were used as shown in Figure 15 with
the different installation method from GX 1, 2, 3.
EXPRESS AMU1 (MEDUSA 2015)
Express AMU1 [4], [25], [26] was developed by the Airbus
Defence and Space for the Russian operator RSCC. The
satellite Express AMU1 (see Figure 16) loaded " Medusa, "
the DLR granted R&D program, which has been the most
classical HTS application in the MFPB method so far. The
Ka-band user multibeam system covered the European part
of the Russian Federation. The measured directivity on the
coverage is presented in Figure 16, which agrees well with
prediction and the high directivity is acquired across the
whole coverage. Single main parabolic reflector with four
colors scheme were used in Tx and Rx antenna design
whose diameter was 1.6 m and 1.1 m, respectively, achieving
18 spot beams with 0.75 beamwidth. The Rx MFPB
feed cluster is presented in Figure 17. The multibeam
antenna system produced 18 single circular polarization
user spot beams and 2 dual circular polarization gateway
FEBRUARY 2022
Figure 18.
Sky Muster satellite [28] and Ka-band multibeam layout [29].
beams. And 5 to 9 horns were used per user beam. One
shared feed scheme between adjacent spot beams was
applied in 7 feed per beam method. Dual-frequency horns
were needed in shared feeds between adjacent user spot
beams with 4 input ports of 2 LHC and 2 RHC signals. If
some ports were not used in user beams, they were able to
form gateway beams. However, there will be no need to
use dual-frequency horns in SFPB multibeam antenna system.
Hence there will be more complexity with MFPB
feeds and BFNs.
SKY MUSTER (2015)
The Sky Muster [28] (see Figure 18) were operated by
NBN Co Limited (NBN Co) including two satellites,
NBN Co 1 A and 1B, both of which are Ka-band highthroughput
broadband GEO satellites with 101 multispot
beams covering Australia. The multibeam layout [29] is
shown in Figure 18, two kinds of beams with the beamwidth
of 0.3 and 0.7 were designed and produced by 2
suites of 4 combined Tx and Rx reflector antennas in the
SFPB method.
EUTELSAT 172B (2017)
Eutelsat 172B [30], [31] (see Figure 19), built by Airbus
Defence and Space and located at 172 East, carried a
high throughput Ku-band payload designed for broadband
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