Transcript
Models
612 and 625 Loop Arrays
Spectrum Monitoring & Management Systems | Broadcast & Communication Antennas | Communication Intelligence | Direction Finding Systems
FEATURES • E a s y t o i n s t a l l • E a s y t o t r a n s p o r t • C o m p a c t , l o w p r o f i l e • C o n f i g u r a b l e f o r m a n y d i f f e r e n t applications • I d e a l f o r s m a l l s i t e s
E l ec tric ally Sm all A n te n n as E lectri cal l y sm al l an ten n as can b e used to ad van tag e i n a w i d e ra nge of receiving a p plications. The inefficiencies inherent in small antennas have the same effect a s o th er so urces o f n o i se o n th e si g n al - to - n o i se rati o . W h en externa l nois e is g r eater th an th e n o i se fro m an ten n a i n effi ci en c y (an d i n terna l electronics , if p r e sen t), an an ten n a i s sai d to b e “extern al l y n o i se l i m i ted .” In this ca s e, the higher level o f extern al n o i se d o m i n ates th e system si g n al - to - n o i se ra tio, rendering the in t ern al n o i se i n si g n i fi can t. Th us, w h en extern al n o i se i s rela tively high, s ma ll r e ceiving antennas can work as well as full-size, fully efficient antennas. (This a ls o m ean s th at ful l y effi ci en t an ten n as n eed b e l o cated at electrica lly quiet s it es to ach i eve th ei r ful l p o ten ti al .) Lo o p A n te n n as A l o o p an ten n a fun cti o n s as a m ag n eti c d i p o l e. A n i n ci d ent electroma gnetic w a ve i n d uces a curren t i n th e l o o p ; a m atch i n g tran sfo rm e r ins ide the loop c oup l es th e i n d uced curren t i n to a 5 0 Ω l o ad , ei th er an am p l if ier or a length of c o a x running to the receiver. O n e advantage of loops over dipoles is their low input impedance. A loop’s p e r fo rm an ce i s rel ati vel y un affected by b ui l d i n g s, trees, sn o w, etc., which tend t o sh o r t o ut rad i ati o n en erg y n ear th e el em en t. M o reover, s ince the ra dia tion r e s i stan ce o f el ectri cal l y sm al l an ten n as i s l o w , m utual effects a re genera lly in s ig n i fi can t, en ab l i n g l o o p s to b e co n fi g ured i n vari o us arrays tha t ta ilor their p e r fo rm an ce to p ar ti cul ar recei v i n g req ui rem en ts. Lo o p s a re of ten a rra yed in ro w s, o r “arm s” o f fo ur, ei g h t, o r si xteen l o o p s to p rov i d e a grea t va riety of r a d i ati o n p attern s. Th e b asi c l o o p i s a l o w - i n d uctan ce al um i n um tub e, fed at i ts upper midpoint via a b r oad b an d , p assi ve m atch i n g n etw o rk . Th e n etw o rk o utp ut feeds a coa xia l ca ble t h a t run s th ro ug h o n e o f th e tub es to th e b ase w h ere i t exi ts the loop, a s s uring e le ctri cal b al an ce at al l freq uen ci es. Th e b ro ad b an d m atching network is d e si g n ed to p rov i d e an o p ti m um i m p ed an ce m atch fo r m a xi mum power tra ns fer ove r th e 2 –3 2 M Hz b an d w i d th . A l l co m p o n en ts are w aterp roof a nd imper vious t o th e effects o f sal t sp ray an d ul trav i o l et rad i ati o n .
Model 612-1
R a diation Patte rn s Th e az i m uth al p attern o f a si n g l e l o o p (M o d el 6 1 2 - 1 ) i s a f igure-eight ( r = c osq ) at th e h o ri zo n , i n creasi n g l y o m n i d i recti o n al at h i g h er a ngles of a rriva l, a n d v i r tual l y i n d ep en d en t o f az i m uth at an g l es o f arri val ab ove 45 degrees . The m a ximum gain of a single loop at the horizon is 5 dBi, the same as that of a ve r ti cal l y p o l ari zed w h i p . Th e overh ead g ai n i s al so 5 d B i , ma king the s ingle l o o p an excellent choice for shor t-range communications. (The whip has a null overhead, limiting its usefulness for shor t ranges.) The signal from two or thogonal l o o ps (612-2 or 625L) can be combined to provide a per fectly omnidirectional p a ttern at al l az i m uth s (si n 2 q + co s 2 q = 1 ), w i th a g ai n o f 2 dBi. B ea m Form in g S ig n al s fro m m ul ti p l e l o o p s can b e co m b i n ed i n p h ase, o r “bea mformed,” with a r esul ti n g d i recti o n al p attern h av i n g a m a xi m um g ai n at so me a ngle below the ze n i th . A d d i n g l o o p el em en ts i n creases g ai n an d d i recti o n a lity. Bea mforming is a cco m p l i sh ed by b ri n g i n g th e feed cab l es fro m each el em e nt in a n a rra y to a d e l ay/ co m b i n er un i t, o r b eam fo rm er, l o cated at th e array’s phys ica l center. I n u n id i recti o n al b eam fo rm i n g , si g n al s fro m each el em en t are dela yed by mea ns o f ap p ro p ri ate l en g th s o f co a xi al cab l e, o r d el ay l i n es, th en s ummed in a hybrid c om b i n er. In b i d i recti o n al b eam fo rm i n g , th e si g n al s are sp lit a nd fed into two s e parate sets o f d el ay l i n es, th en sum m ed i n tw o sep arate combiners .
6 1 2 - 62 5 - 06 - 1 0 - 1 0
© TC I — A l l r i g h t s r e s e r v ed | D a t a a n d specifica tio n s su bj e ct t o change wi t hout not i ce | N ot for di st ri but i on wi t hout pri or pe rmi ssi on fr om TC I.
TC I I n t e r n a t i o n a l , I n c . | 3 5 4 1 G a t e w a y B l v d . | Fr e m o n t , C A 9 4 5 3 8 | + 1 . 5 1 0 . 6 8 7 . 6 1 0 0 | w w w . t c i b r . c o m
Ampl i f i e r s Amplif i e r s a r e o f t e n u s e d w i t h l o o p a r r a ys t o b o o s t the signal pri or t o i nser t i o n i n t o t h e c a b le r u n . Th ey a r e g en eral l y re com mend ed w hen a t t e n u a t ion is exc e s s ive ow in g to l o n g runs o f fe e d e r o r i n a d e q u a t e r e c e i ve r s e n s i t i v i t y . Amplifiers follow t h e hy b r i d c o m b i n e r s a n d d e t e r m i n e t he system n oi se l evel at t hat p o in t . The st a n d a r d a m p l i f i e r u s e d by TC I i n l o o p a r r a ys has 23 dB of g a i n ; o t h e r va l u e s a r e a va i l a b l e t o m e et specific re qui r ement s. DC p o w e r is fu r n is h e d t o t h e am p l i fi er th roug h t he R F c o a x. H ig h -p a s s filt e r s t o b lo c k in t er feren ce from M F s t a t i o n s o r l o w - p a s s f i l t e r s t o b l o c k T V and FM si gna ls c an b e i nc o r p o r a t e d in t o t h e a m p lifie r a s req ui red . TCI u s e s t h e b e s t a m p l i f i e r s a va i l a b l e ; n ever theless, a mpl i fi er s ar e susc ep t ib le t o ove r loa d , s om e t im e s g en erate interm o d u l a t i o n p r o d u c t s , a n d a l w a ys a d d t o sys tem noise. Unless a m p l i f i e r s ar e r e q u i r e d , c o nve r s i o n t o a passive syste m may b e ad vi s a b le . La rge A r r ays of Loo p s Multip l e s m a l l a r r a ys a r e o f t e n c o m b i n e d i n rosette confi g ur at i o ns. O ne c om m o n r os e t t e c on s is t s o f fo ur bidire c t i o n a l a r m s ex t e n d i n g f r o m a c o m m o n c e nter, with each a r m c o n s i s t i n g o f e i g h t l o o p s . Th i s 4 - a r m, 32-loop confi g ur at i o n c an p r o d u c e e ig h t b e a m s , o n e for each 4 5 de grees o f az i mut h. S om e a r r a ys u s e o n ly fo u r el em en ts per ar m ; o t h e r s fo r l o n g - r a n g e a p p l i c a t i o n s u s e a s many as si xtee n fo r hi g h d i r ec t io n a l g a in a t lo w a n g le s o f a rri val . D esi gn N o t es The fo l l o w i n g d e s i g n n o t e s s h o u l d b e c o n s idered in pl a nni ng a l o o p ar r a y : ▪ ▪ Th e b e s t f r o n t - t o - b a c k r a t i o i s a c h i eve d by making th e a r r a y o n e - h a l f w a ve l e n g t h l o n g a t i ts lowest freq uenc y.
▪ ▪ Element spacing should not exceed one-half wavelength at the highest frequenc y to prevent grating lobes in the p attern . ▪ ▪ The gain of an end-fire array increases with the square root of its electrical length; over a range of 2 to 32 MHz th e array g ai n i n creases by a facto r o f fo u r ( 6 dB) . ▪ ▪ A m p l i fi ers ad d system n o i se (3 .8 d B for the 23 dB un i t). Mod e l 6 1 2 The Model 612, with a nominal diameter of two meters, is the smallest element in the TCI family of loop antennas. The 612 loop stands about 7 feet (2.2m) tall, depending o n m o un ti n g typ e. M o d el 6 1 2 l o o p s fo r tempora r y or tran sp o r tab l e ap p l i cati o n s are m o un ted o n steel tripods ; for p erm an en t o r h i g h w i n d / i ce ap p l i cati o n s, th ey a re mounted o n al um i n um p o sts b o l ted to co n crete p ad s. Mod e l 6 2 5 an d Mod e l 6 2 5 L Model 625 loops have a nominal diameter of three meters an d are arrayed i n th e sam e m an n er as 6 12 loops . The 625 elements are used where their lower noise figure is ad van tag eo us, i e, at q ui et si tes aw ay fro m urba n a rea s ( s ee N o i se F i g ure Tab l e). The Model 625L is a pair of or thogonal loops mounted on a common a xis. With a diameter of 3.66 meters, the 625 has th e l arg est ap er ture o f th e TC I l o o p s. In d i vidua l outputs fro m each l o o p p rov i d e b i d i recti o n al si g n al s; outputs ca n al so b e co m b i n ed to p rov i d e o m n i d i recti o n al covera ge.
Po w e r S uppl y Mu l t i co u p l er U n i t ( PS M ) A c o m b i n a t i o n p o w e r s u p p l y a n d H F m u l t i c o u p ler unit (PSM) is n o r m a l l y m o u n t e d i n a r a c k i n t h e r e c e i ve r building. The PS M s u p p l i e s D C fo r t h e a r r a y p r e a m p s v i a the user’s RF co a x . Th e PS M a l s o “ p i c k s o f f ” t h e R F f r o m the coa x and dist r i b ut es i t t o th e s t a t ion ’s r e c e ive r s v ia a n um b er o f B N C co n n e c t o r s ( u s u a l l y fo u r ) o n t h e b a c k o f t h e unit. Systems wi t h o u t a m p l i f i e r s n o r m a l l y r e t a i n t h e PS M chassis as a ce n t r a l s o u r c e fo r t h e a r r a y ’s R F o u t p u t , w h i c h may include po w er sp l i t t er s t o fe e d m u lt ip le r e c e ive r s . Mode l N umbe r in g S ys t em Lo o p e l e m e n t s c a n b e a r r a ye d i n m a ny c o n f i gurations. TCI n o menc l at ur e d e s c r ib e s t h e m a s follo w s : 1 st t er m:
nu m b e r of a r m s in t h e a r r a y
2 nd t er m: ele m e n t t y p e , 6 12 o r 6 25 3 r d t er m: nu m b e r of lo o p e le m e n t s in e a ch arm 4 t h t er m:
sp a c in g b e t we e n e le m e n t s , in m eters
5 t h t er m:
o p e r a t ion m od e of t h e e le m e n t ( U , u n id ir e c t io n a l, or B , b id ir e cti o n al )
Th u s , a n a r r a y o f fo u r b i d i r e c t i o n a l a r m s , e a c h having eight ele m e n t s s p a c e d fo u r m e t e r s a p a r t w o u l d be designated as a M o d e l 4 - 6 1 2 - 8 - 4 - B . Th i s i s t h e 8 - d i r ection rosette de sc r i b ed ab ove in “ La r g e Ar r a ys o f Loo p s . ”
Plan and Elevation View Model 625 L Specifications shown in tables
Radiation Pattern for Model 612-1 and 625-1 (directive gain in dBi)
Plan and Elevation View Model 612-1 one element only Model 612-2 both elements
Impedance (output): 50 ohms
SPECIFICATIONS Power Supply Multicoupler Unit
Beam Former Output Connector: 2-type-N jacks
Frequency Range: 2–32 MHz
TCI Model 1-612-8-8-U (or B)
RF Impedance: 50Ω
Frequency: 2–16 MHz
VSWR: 1.2:1 maximum
Front-to-Back Ratio: 13 dB (2–16 MHz)
Connection located on rear panel: BNC–jacks
Directive Gain 2 MHz 7 dBi 5 MHz 10 dBi 10 MHz 13 dBi 16 MHz 14 dBi
Power Requirements: 115/220 V, 1.3/0.7 A, 50–60 Hz, single phase Size: 19”x3.50”x13.75” deep
TCI Bi-directional End-Fire Loop Arrays
TCI Model 612-1
Frequency: 2–32 MHz
Composed of a single loop w/amplifier and power supply. Multicoupled outputs available, optionally.
Polarization: Vertical Directive Gain: 2 MHz 5 dBi 5 MHz 8 dBi 10 MHz 10 dBi 20 MHz 13 dBi 30 MHz 14 dBi
Frequency: 2–32 MHz Directive Gain: 5 dBi
TCI Model 612-2
Direction of Radiation: Array is bi-directional and can receive signals simultaneously from either end-fire direction
Composed of two single loops disposed orthogonally and fed either individually or with a hybrid combiner to form an omni azimuthal pattern. (Supplied with 1 amplifier and 1 power supply.) Multicoupled outputs available, optionally.
Azimuth Beamwidth
5 MHz
Frequency: 2–32 MHz
30 MHz 54°
3 dB points
86°
Elevation Angle at upper
5 MHz
30 MHz 30°
3 dB points
Front-to-back Ratio
(4–32 MHz)
Loops in Array
Directive Gain:
80°
5 dBi when fed individually 2 dBi when fed with hybrid combiner.
TCI Model 1-612-8-4-U & TCI Model 1-625-8-4-U
13 dB minimum
Azimuth and Elevation Directive Gain Patterns 2.0 MHz
8
Array Length:
30 meters (98 feet)–612,
31 meters (102 feet)–625
5.0 MHz 30
o
30o
20
o
20
o
10
10
Inter-Loop Spacing: 4 meters (13 feet)
--5
0
5
0o
10
--5
10
Element Height: 2 meters (78 inches)–612 3.4 meters (134 inches)–625 4.4 meters (174 inches)–625L
2 MHz 4 MHz 8 MHz 15 MHz 30 MHz
612-1
612-8-4-B
625-8-4-B
625L
51.8 39.8 30.3 21.8 16.5
46.2 34.7 24.7 15.8 9.4
36.6 26.9 17.0 11.0 10.6
39.3 30.8 21.7 15.0 16.3
Frequency
2 MHz 4 MHz 8 MHz 15 MHz 30 MHz
612-1 0.75 1.5 2.2 2.9 2.7
612-8-4-B .43 .81 1.28 1.50 2.00
625-8-4-B
20
1.30 2.00 3.13 3.31 1.74
30
o
o
20
o
10
--5
0
5
10
15
o
2 MHz 8 MHz 15 MHz 30 MHz
--5
10 MHz
612-8-4-B
625-8-4-B
625L
4.70 1.61 1.21 1.21
5.81 3.09 1.67 1.25
1.92 1.25 0.76 1.44
2.75 1.72 1.12 2.45
0
5
10
15
0
o
o
30 MHz 30o
20
10
--5
0
5
30o
o
20
o
10
0o
10
10
0.91 1.45 2.08 2.23 1.02
612-1
10
0o
--5
0
5
0
10
o
o
o
o
10
o
20o
o
30
20
30
o
o
30 MHz
10 MHz
Frequency
30o
5.0 MHz
o
30
30o
Field strength incident on array required to drive amplifier to 1 dB compression point (v/m)
o
30o
20
625L
o
10
30o
Effective height (m) TCI loop arrays at output of PSM 1-1 or PSM 2-1
10
o
20
Noise figure (db) TCI loop arrays (systems include amplifier noise figure)
5
o
0o
o
2.0 MHz
Frequency
0
o
-5
0
5
10
15
o
20
o
20
10
o
10
0o
o
o
-5
0
5
10
15
0
Perfect ground Average ground σ = 5mS/m,E1 = 10
© TCI — A l l r i g ht s r e s e r ved | Da t a a n d specifica tion s su bj ect t o change wi t hout not i ce | N ot for di st ri but i on wi t hout pri or pe rmi ssi on fr om TC I.
TC I I n t e r n a t i o n a l , I n c . | 3 5 4 1 G a t e w a y B l v d . | Fr e m o n t , C A 9 4 5 3 8 | + 1 . 5 1 0 . 6 8 7 . 6 1 0 0 | w w w . t c i b r . c o m
