This document discusses various concepts related to antennas for space applications, focusing on satellite antenna footprints and different coverage types, including global, elliptic, and shaped-beam antennas. It also covers the principles of parabolic reflector antennas and phased-array antennas, detailing their configurations and functionalities. Additional topics include beam-forming networks and the evolution of satellite antennas.

1. An Introduction to
Antennas
for Space Applications
Lesson 2
Dr. ing. Marco Lisi
(marco.lisi@ieee.org)
Space Challenges, Sofia, 2015

2. Outline
LESSON 2
• Satellite antenna footprints
• Satellite orbits
• The geostationary (Clarke’s) constellation
• Global coverage antennas
• Elliptic coverage antennas
• Spot coverage (multi-beam) antennas
• Contoured coverage (shaped-beam) antennas
• Beam-forming networks (BFN’s)
• Parabolic reflector antennas
• Phased-array antennas
• Active array antennas
2

3. Satellite Antenna Footprint
3
The antenna footprint is the area on the Earth
illuminated by the antenna with a specified minimum
gain.

4. Iso-gain or Iso-EIRP Contours
4
On the antenna footprint it is possible to trace the iso-gain
contours.
In case of satellites for TV broadcasting, it is usually reported
the EIRP (“Effective Isotropic Radiated Power”), in dBW, or
the corresponding needed diameter of the ground antenna.

5. Satellite Orbits

6. Geostationary Orbit
6

7. The Clarke’s Constellation
7

8. Global Coverage from GEO Orbit
8

9. Global Coverage Antenna
9
d
θ3dB = 17.5º
d = circular aperture diameter
𝜃𝜃3𝑑𝑑𝑑𝑑 = 70
λ
𝑑𝑑
𝐺𝐺𝑚𝑚𝑚𝑚𝑚𝑚 = η (
𝜋𝜋𝑑𝑑
λ
)2 η= 0.55
𝐺𝐺𝑚𝑚𝑚𝑚𝑚𝑚 = 20 dB @ 4 GHz, d ≅ 0.3 m (horn antenna)

10. Global Coverage from GEO Constellation
10

11. Evolution of Satellite Antennas
11

12. Elliptic Coverage (Europe)
12

13. Satellite Elliptic Coverage (North America)
13

14. Spot beam Antenna

15. Multi-beam Coverage (Eutelsat W2A)

16. Shaped Beam Antenna
The coverage area is shaped to fit at best the service area:
• By shaping the antenna reflector (e.g. elliptical reflector);
• By using multiple feed antennas
16

17. Shaped Beam Antenna (multi-feed)
17
Feed Array
Reflector
A
B
C
D
D
C
B
A
Feed Array
Reflector

18. Contoured Coverage
18

19. Beam-Forming Networks
19

20. The Parabolic Reflector
20

21. Parabolic Reflector Antennas
A paraboloid is the surface generated by a parabola
revolving around its axis.
The parabolic reflector functions due to the geometric
properties of the paraboloidal shape: any incoming ray that
is parallel to the axis of the dish will be reflected to a central
point, or "focus".
21

22. Parabolic Antenna Configurations
22

23. Front-fed Reflector Antenna
23

24. Off-set Fed Reflector Antenna
24

25. On-set and Off-set Cassegrain
Real Focus
Virtual Focus
Hyperbolic
Subreflector
Virtual
Equivalent
Reflector
D
25

26. On-set and Off-set Gregorian
1st Ellipse Focus
2nd Ellipse Focus
Elliptic
Subreflector
Virtual
Equivalent
Reflector
D
26

27. Phased-Array Antennas
GPhased-Array (dBi) = G Single Element (dBi) + 10 x log10 N
27

28. Phased-Array Antennas: Globalstar
28

29. Phased-Array Antennas: Galileo
29

30. Active Array Antennas: Cosmo-Skymed
30

31. Korean
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