Literature Review ofConformal antenna Presented by NAGRALE NILESH B. 11EC63R23 RF & Microwave Engineering IIT KHARAGPUR.
Outlines:• Challenges• Conformal antenna• Examples• Calculation of parameter based on requirement• Design
Challenges:• Aerodynamic drag(Used for mobile system)• Large angular coverage• High gain• Fast pointing direction variation
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.
Examples:Raysat U.S. based company provides conformalantenna for mobile TV application.Their products are• SpeedRay 1000• StealthRay 5000• StealthRay 2000(Two way)
Calculation of antenna gain(cont.)(C/N)dB=(EIRP)T +(Gr/T) – path loss –k –BandwidthBandwidth=36MHz =75.56dBHzEIRP= 52dBWC/N=5.5 dBWK=-228.59Gr/T=5.5-52+204.48-228.59+75.56 Gr/T = 4.95dB noise figure=0.5dBNF=1+Tsys/T0Tsys =(1.12201-1)* 290Tsys =35.38535KGr=35.3835* 3.12Gr=110.6116293Gr=20.438dBDiameter of antenna=60 cmEffective aperature area=Ae =π * (0.60)2/4 *0.5=0.14137 m2Power received =1.347977873*10-12Power received=-118.703dBw
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.
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.
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.
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
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
References: 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 Ashkenazy,J. Shtrikman, S.Treves “Conformal microstrip arrays on cylinder” Microwaves, Antennas and Propagation ,Volume: 135 , 1988 , pp.no. 132 - 134Knott P. “Antenna design and beamforming for a conformal array demonstrator”IEEE Aerospace conference 2006Knott 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. 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. 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
References: 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. Knott, P.; Löcker, C.; Algermissen, S. ”Antenna element design for a conformal antenna array demonstrator” IEEE Aerospace conference,2011,pp.no.1-5. Munson, R. E “Conformal microstrip communication antenna” IEEE Military conference, Vol. no.2,1989,pp.no.23.3.1-23.3.4 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.www.raysat.com