4. Conformal antennas:
• An antenna which conforms to a surface whose shape is mainly
determined by considerations other than electromagnetic, e.g.
aerodynamic considerations
• Other possible purpose for using these antennas is making them less
disturbing, i.e. less visible to the human eye since there are integrated on
the structure. This attribute might be useful for urban or military
environments.
• Conformal antennas can be almost any geometry, although the main
structures investigated so far are cylindrical, spherical and conical.
5. Examples:
Raysat U.S. based company provides conformal
antenna for mobile TV application.
Their products are
• SpeedRay 1000
• StealthRay 5000
• StealthRay 2000(Two way)
6. Calculation of antenna gain
For Insat 3A-4B
Satellite Location =93.5 degree E
Frequency= 10.99 GHz
Kharagpur location= 87.31881degree E,22.3304 degree N
cosϒ= cos(Le) cos(Ls) cos(ls-le)+sin (Ls)sin(Le)
cosϒ = 0.925 * 0.994175
cosϒ= 0.9196
d2=re
2+rs
2 -2re rscosϒ
For one sidereal day
rs=42164 Km
d2 =(6373)2+(42164)2-2 * 6373 * 42164*0.9196
d=36390Km
Path loss=(4πd)2/λ2
= 2.8063169*1020
= 204.48dB
7. Calculation of antenna gain(cont.)
(C/N)dB=(EIRP)T +(Gr/T) – path loss –k –Bandwidth
Bandwidth=36MHz =75.56dBHz
EIRP= 52dBW
C/N=5.5 dBW
K=-228.59
Gr/T=5.5-52+204.48-228.59+75.56
Gr/T = 4.95dB
noise figure=0.5dB
NF=1+Tsys/T0
Tsys =(1.12201-1)* 290
Tsys =35.38535K
Gr=35.3835* 3.12
Gr=110.6116293
Gr=20.438dB
Diameter of antenna=60 cm
Effective aperature area=Ae =π * (0.60)2/4 *0.5=0.14137 m2
Power received =1.347977873*10-12
Power received=-118.703dBw
8. Design
Conforming the antenna to the surface saves space and is often essential for
structural reasons, we have different types of design shown below.
• Conformal microstrip arrays on cylinders:
In this paper, they designed and measured results for two X-band
conformal arrays where two 4*4 arrays are built on the surface of a cylinder.
The elements of the array are oriented in the axial direction and the
azimuthal direction too. They have measured return loss and gain versus
frequencies. They found that gain of axial oriented array is 16.7 dB and that of
azimuth oriented array is 17.5dB,Which is nearly as per our requirement.
• Active subarray module development for Ka band satellite communication
system
In this paper, Development of low profile 4*4 element subarray
module(which can be used as building block of large arrays),element is spaced
0.33” apart. Module provides transmit at 29.6GHz.It is designed to scan over +/-
30 ̊ with less than 3dB drop in ERP. The goal was to provide 75 watts ERP at
broadside from each module.
9. Design(Cont.)
• Antenna design and beamforming for a conformal array demonstrator
It presents conformal antenna arrays fitted to a surface of a non planer part
of modern aircraft
An antenna is divided into linear subarray
4 microstrip patch antenna elements designed
at a center frequency of 9.4 GHz. From mesured
result, It is shown that due to mutual coupling
of element in array ,its gain is found to be 12dBi.
• Design and experimental results of a spherical antenna array for a conformal
array demonstrator
It describes development of spherical antenna array with 95*3 antenna
element, it is highly directive, Subarray consists of 3 circularly polarized patch
antennas at center frequency 9.5 GHz. This design provide same gain but has
advantages of steering in both direction i.e. azimuth and elevation angle.
10. Design(cont.)
• Conformal wide-bandwidth antennas and arrays
Very thin antenna structures ,They should be processed preferably on
flexible substrate so that they will conform to the surface without changing surface
geometry.
• A millimeter-wave conformal phased microstrip antenna array on a cylindrical
surface
The use of phased array antennas allows one advantages that other type of
antennas do not have, like beam steering and multiple beams, eliminating
mechanical scanning which usually consumes more power and due to its inertia is
much slower than electronic scanning, so conformal phased antennas have a great
attraction in the area of aviation and spacecraft. A cylindrical conformal microstrip
antenna array due to the light weight, low profile, low cost, integrability with
microwave circuitry and simple manufacturing is an attractive choice among
different other systems.
11. Design(cont.)
• A broadband ship based electronically steered L- band SATCOM antenna.
A broadband ship based electronically steered L-band SATCOM antenna
An antenna for L-band satellite communication system (INMARSAT).
It was mainly used for data and voice communication between ship offshore and
mainland therefore they made mechanically steerable antenna. They got gain
around 22dB.
• Antenna element design for a conformal antenna array demonstrator
This paper presents conformal antenna array with active vibration
compensation using piezoactuators
12. Design(cont.)
• Conformal microstrip communication antenna
Conformal microstrip phased array mounted on fuselage of aircraft. It has
thin conformal randome laminated to antenna,generally this paper discussed four
types of antennas as follows:
• Single element antennas with broad coverage
• Wraparound Omni, missile and satellite antennas
• Fixed beam conformal microstrip antennas
• Electrically scanned microstrip arrays
• A New Low Profile Antenna with Improved Performance for Satellite On-the-
Move Communications
This paper discused design of antenna which is operating at Ku band,which
provide a hybrid scanned phased array antenna to provide good low elevation
angle coverage down to 10° elevation above the horizon
13. References:
[1] S. Sanzgiri', W. Pottenger, D. Bosr and D. Denniston “Active subarray module
development for Ka band satellite communication system”Antennas and
Prpagation Society International Symposium,Volume:2, 1994 , pp no,: 860 - 863
[2] Ashkenazy,J. Shtrikman, S.Treves “Conformal microstrip arrays on cylinder”
Microwaves, Antennas and Propagation ,Volume: 135 , 1988 , pp.no. 132 - 134
[3]Knott P. “Antenna design and beamforming for a conformal array
demonstrator”IEEE Aerospace conference 2006
[4]Knott P. “Design and experimental results of a spherical antenna array for a
conformal array demonstrator”2nd international ITG conference on antennas,2007
pp.no.120-123.
[5] Ferendeci, A.M. “Conformal wide-bandwidth antennas and arrays” 3rd
international symposium on Microwave ,Antennas,Propagation and EMC
Technologies for wireless Communication,2009,pp.no.K7-K10.
[6] Qun Wu; Min Liu; Zi-Rui Feng “A millimeter-wave conformal phased microstrip
antenna array on a cylindrical surface” International symposium on Antennas and
Propagation,2008,pp.no.1-4
14. References:
[7] Pivit, F.; Loffler, D.; Wiesbeck, W. “ broadband ship based electronically steered L-
band SATCOM antenna” International symposium on Antennas and Propagation
Vol no.2,2003,pp.no.456-459.
[8] Knott, P.; Löcker, C.; Algermissen, S. ”Antenna element design for a conformal
antenna array demonstrator” IEEE Aerospace conference,2011,pp.no.1-5.
[9] Munson, R. E “Conformal microstrip communication antenna” IEEE Military
conference, Vol. no.2,1989,pp.no.23.3.1-23.3.4
[10] Yuanyuan Jiang,Foti, S.J., Sambell, A., Smith, D. “A New Low Profile Antenna with
Improved Performance for Satellite On-the-Move Communications” 3rd
International symposium on Microwave ,Antennas,Propagation and EMC
Technologies for wireless Communication,2009,pp.no.52-69.
[11]www.raysat.com
