Analysis of Feeding Systems for

Double Reflector Spherical Antennas

A.Sargsyan1,2, H.Abrahamyan1,2, Y.Alkhatib1 , G.Hakobyan1

1 State Engineering University of Armenia2 National Institute of Metrology

IRPhE-2012, October 17, 2012, Yerevan

Outline

• Introduction

• Different types of antennas suitable as a main

feed

• Antenna arrays as feeds for correcting reflector

• Supplementary Linear Feed (SLF) for ROT-

54/2.6

• Conclusion

Introduction

• Application of Double Reflector antennas: in Radio

astronomy, as well as in Deep Space Communication

for microwave ranges of wavelengths

• double reflector-systems of Cassegrain and Gregory

• crucial are: the weight, hardness of the constructing

materials, costs, etc.

• due to the deformation of materials, movement

deformations, etc

• large spherical double reflector antennas

with unmovable main spherical mirror and

mobile correcting mirror

• Prof. Paris Herouni, the end of 50-th of last

century

Radio-optical telescope ROT - 54/2,6

• was completed during 1985-87 and placed

on Aragats mountain (National Institute of

Metrology, Orgov)

Single antenna feeds

___ - conical horn,

------ - open- end waveguide

-..-..-..- - open- end waveguide

with Teflon sleeve

and vibrator.

-.-.-.- - pyramidal corrugated horn

Double reflector spherical antenna

(DSA)’s feeding system

• optimal feeding of the secondary

correcting reflector is possible by using

different types of single feeds

Antenna arrays as feeds for

correcting reflector

a) horizontal surface b) vertical surface

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

-100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100

smooth spheric cone

1

F

-10º -5º 5º 10

º

º

Antenna arrays as feeds for

correcting reflector

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

-100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100

smooth spheric cone 1

F

-10º -5º 5º 10

º

º

is able to move in space ~ 18.75 min of arc

the maintenance of the radiation

optimal condition of ROT- 54/2.6

antenna feed is received when the

distance between SWA parts

constitutes 25mm

Supplementary Linear Feed (SLF) for

ROT-54/2.6

SUF can be improved up to 0.707R0

That made the SUF increase by 17.8%.

Conclusion

• Double Reflector Spherical Antennas have

a couple of considerable advantages

against parabolic antennas.

• In order to enjoy these advantages

possibly, suitable feeding system should

be applied.

Thank you for your attention