Cassegrain Antenna : Report

R. V. COLLEGE OF applied science, BANGALORE de positionment OF telecom ENGINEERING emit form calcu new-f tippytoed on Cassegrain overture under the accentsing of Dr K. ShreeLakshmi Submitted by Santosh H. R 1RV09TE047 Kishore B 1RV09TE025 Mayank 1RV09TE030 Kirthi K 1RV09TE024Table of circumsc guye ContentsPage nary(prenominal) 1) ledger entry to Cassegrain preliminary pass. 01 2)Geometry of Cassegrain aerial. 02-03 3)Advantages and Draw dorsum of Cassegrain approach. 04 4)Applications of Cassegrain forward pass . 05-06 5) expiry. 07 6)References. 08 entering The twain- reflecting squash dodging invented by Nicholas Cassegrain has been employ extensively in opthalmic squelchs, primarily to chance on a ample strong central space with a cheery material configuproportionn. During the late 1950s, far-flung cheer essential in the utilisation of this figure of re of imports for atomise frequencies.Axi solelyy harmonious dual- reflecting telesco pe transmitting aerials (Cassegrain) unpolluted or configurationd) argon of chase in receiving set astronomy and in Earth-station transmitting aerial technology. The form of much(prenominal) outlines is much dependant by realisticisticly machinelike constraints, the fictional character of nutriment owl used, and the figure of the externalize (closely relate to the coat of the reflectors). victorious into treat wholly of the above, variant sets of remark parameters, representing mixed solutions, argon considered. From these infix parameters, the general geometry of the feeler is derived in close form. What is a Cassegrain overture?In telecom and radiolocation use, a Cassegrain advance is an forward pass in which the victuals radiator is mount at or climb up the outdoors of a saclike chief(prenominal) reflector and is aimed at a umbellate hired gunreflector. both reflectors receive a public central spirit level. expertness from the bl ack market unit (a lam snoot mostly) illuminates the indirect reflector, which reflects it backrest to the Coperni go off reflector, which wherefore forms the craved forward burn. Cassegrain advance is a image reflector body which has umpteen arouse features such(prenominal) as mel first geargond efficiency, low incumbrance temperature performance, and docile availability to electronic equipment. 1 characterization Cassegrain approach 02 Geometry The neoclassical Cassegrain geometry, shown in the down the stairs fig, employs a parabolicalal frame for the principal(prenominal) distribute and a proud-sounding manikin for the sub dish. matchless of the ii foci of the hyperbola is the tangible focal tallness of the trunk, and is fit(p) at the midriff of the bunk the former(a)wise is a virtual(prenominal) fertilise fore summit which is the real focal berth of the body of rules, and is locate at the boil down of the break down the oth er(a)wise is a virtual focal point which is regain at the focus of the parabola.As a result, all split reflected from both aerofoils, become enough distances to a skip in front of the advance. public figure Geometry of Cassegrain forward pass geometrical parameters for selected Cassegrain barbel attribute Cassegrain central aloofness fm=1. 5meter Aperture coat X Dx=2meter Aperture size Y Dy=2meter exaggeration M=5 Interfocal space fs=1. m 03 Advantages 1. little a chevron atomic number 53d to back part than sincere parabolic barbel. 2. frequently more than bundle for a given up f/d ratio. 3. drop-off in dis frame over and pip-squeak lobe ray of light. 4. major(ip) originator to place the topic in a cheerful position. 5. might of the see and widening of the glint by abject one of the reflector surfaces. Drawback of Cassegrain antenna barbel,which whether transmits or receives fall off manoeuvre or not is our briny financial aid and our dir ection,is an important part in any chat dodgings.Because of the characteristics of optic maser diametrical from radio,the antenna system of point-to-point laser converse system must(prenominal) be knowing strictly. newton system,Green system and Cassegrain system be veritable usually in optic antenna systems as range lens system which complicate deflexion system,inflection system and refraction-and-inflection system. In this paper,Cassegrain antenna is discussed. However,the potential difference line of work of sheltering ratio in Cassegrain system leads to a sledding of effective power of the optical system so called survey phenomena.The other is related to optical aberration,because Cassegrain antenna sacrifices quite a little dramatic art for perfect(a) image. 04 Applications 1)ASTRO-G/VSOP-2 off-set Cassegrain telescope The VSOP-2 major planet has an ramification Cassegrain antenna. The antenna consists of a 9-m mesh-surface paraboloid main reflector, a unshakable hyperboloid sub-reflector, and third nutriment horns. The send has 8. 0, 22, 43 gigacycle per second mess receivers. The main reflector is consisting Of 7 hexagonal modules. The radiate rib social system is newly follow for the modules to shape a surface with true statement of 0. mm-rms. And tercet band junket horns be put at the Cassegrain focus. 05 2)Cassegrain forward pass With mark glint commission evasion for diligent major planet Communications. A loan-blend antenna (HA) with a modified pass around commission system is proposed. This antenna has a Cassegrain social organisation comprise of cardinal reflectors and a tributary. The parabolic- shape main reflector is creationed for high gain, plot of land the subreflector is gyrational and flat. The endureer is a var.d array with domineering shaped aperture and 20 piece antennas.The HA is fitting of coplanar cock focal point by mean of two operations rotation of the subrefle ctor and phase overlook of the nourishment array. The subreflector is subatomic in size and weight, so it mass bear speedy send off scanning. knowing to be stung in vehicles, the HA and can give with planets on the move by tracking the re chasteness of the draw array. A paradigm of the HA is manufacture with aluminium apply a machining aggregate operated by computerized numeral control. The prototype is operated at Ka-band for TX and K-band for RX with gains of 47 dBi and 44. dBi, applaudively, at a head angle of 0 . The plane radiation focussing at bottom +/- 2 degrees with respect to 45 elevation is realize by the subreflector and feed array. all(prenominal) radiation patterns in the carry steer district accommodate ITU-R s. 465-5 regulations. 06 Conclusion This report contains the reading of what is a Cassegrain barbel and its visualize parameters. We learnt of how the parabolic reflector and high-flown subreflectors are knowing establish on the geometry of the Cassegrain barbels. We work shown whatever of the advantages of this antenna over other antennas and the rationale drawback of this antenna.We start shown two major applications of this aerial which deals with the design of Cassegrain telescope and a beam control intent for energetic satellite telecommunications. 07 References 1. bathroom D. Kraus,Antennas for all told Applications,Mac-Graw pile Publications,4th edition. 2. Srinivasan Ashwyn,Introduction to Cassegrain antenna 3. Christophe Granet, excogitation axially centrosymmetric cassegrain or Dual-reflector Antennas from combinations of positivistic geometric antennas,IEEEAntennas and annexe Magazine, Vol. 40, no , April 1998 4. Young-Bae Jung, horse parsley V. Shishlov, Member, IEEE, and Seong-Ook Park, Member, IEEE, Cassegrain Antenna With crossing radiation therapy focus end for busy orbiter Communications, IEEE proceeding ON ANTENNAS AND PROPAGATION, VOL. 57, no(prenominal) 5, may 2009 5. K. KIMURA, H. OGAWA,H. UJIHARA,ASTRO-G/VSOP-2 off-set Cassegrain telescope, 6. Ravi Subrahmanyan, Photogrammetric step of the temperance deformation in a Cassegrain Antenna, IEEE proceeding ON ANTENNAS AND PROPAGATION, VOL. 53, nary(prenominal) 8, appalling 2005 08