Loop Arrays Easy install Easy transport Compact, low-profile Conf

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Loop Arrays Easy install Easy transport Compact, low-profile Conf

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Loop Arrays
Easy install Easy transport Compact, low-profile Configurable many different
applications
Ideal small sites
Model 612-1
Electrically Small Antennas Electrically small antennas used advantage wide range receiving applications. inefficiencies inherent small antennas have same effect other sources noise signal-to-noise ratio. When external noise greater than noise from antenna inefficiency (and internal electronics, present), antenna said "externally noise limited." this case, higher level external noise dominates system signal-to-noise ratio, rendering internal noise insignificant. Thus, when external noise relatively high, small receiving antennas work well full-size, fully efficient antennas. (This also means that fully efficient antennas need located electrically quiet sites achieve their full potential.) Loop Antennas loop antenna functions magnetic dipole. incident electromagnetic wave induces current loop; matching transformer inside loop couples induced current into load, either amplifier length coax running receiver. advantage loops over dipoles their input impedance. loop's performance relatively unaffected buildings, trees, snow, etc., which tend short radiation energy near element. Moreover, since radiation resistance electrically
small antennas low, mutual effects generally insignificant, enabling loops configured various arrays that tailor their performance particular receiving requirements. Loops often arrayed rows, "arms" four, eight, sixteen loops provide great variety radiation patterns. basic loop low-inductance aluminum tube, upper midpoint broadband, passive matching network. network output feeds coaxial cable that runs through tubes base where exits loop, assuring electrical balance frequencies. broadband matching network designed provide optimum impedance match maximum power transfer over 2-32 bandwidth. components waterproof impervious effects salt spray ultraviolet radiation. Radiation Patterns azimuthal pattern single loop (Model 612-1) figureeight cosq) horizon, increasingly omnidirectional higher angles arrival, virtually independent azimuth angles arrival above degrees. maximum gain single loop horizon dBi, same that vertically polarized whip. overhead gain also dBi, making single loop excellent choice short-range communications.
(The whip null overhead, limiting usefulness short ranges.) signal from orthogonal loops (612-2 625L) combined provide perfectly omnidirectional pattern azimuths (sin2q cos2q with gain dBi. Beam Forming Signals from multiple loops combined phase, "beamformed," with resulting directional pattern having maximum gain some angle below zenith. Adding loop elements increases gain directionality. Beamforming accomplished bringing feed cables from each element array delay/combiner unit, beamformer, located array's physical center. unidirectional beam forming, signals from each element delayed means appropriate lengths coaxial cable, delay lines, then summed hybrid combiner. bidirectional beam forming, signals split into separate sets delay lines, then summed separate combiners. Amplifiers Amplifiers often used with loop arrays boost signal prior insertion into cable run. They generally recommended when attenuation excessive owing long runs feeder inadequate receiver sensitivity. Amplifiers follow hybrid combiners determine system noise level that point. standard amplifier used loop arrays gain; other values available meet specific requirements. power furnished amplifier through coax. High-pass filters block interference from stations lowpass filters block signals incorporated into amplifier required. uses best amplifiers available; nevertheless, amplifiers susceptible overload, sometimes generate intermodulation products, always system noise. Unless amplifiers required, conversion passive system advisable. Large Arrays Loops Multiple small arrays often combined rosette configurations. common rosette consists four bidirectional arms extending from common center, with each consisting eight loops.
This 4-arm, 32-loop configuration produce eight beams, each degrees azimuth. Some arrays only four elements arm; others long-range applications many sixteen high directional gain angles arrival. Design Notes following design notes should considered planning loop array: best front-to-back ratio achieved making array one-half wavelength long lowest frequency. Element spacing should exceed one-half wavelength highest frequency prevent grating lobes pattern. gain end-fire array increases with square root electrical length; over range array gain increases factor four dB). Amplifiers system noise (3.8 unit). Model Model 612, with nominal diameter meters, smallest element family loop antennas. loop stands about feet (2.2m) tall, depending mounting type. Model loops temporary transportable applications mounted steel tripods; permanent high wind/ice applications, they mounted aluminum posts bolted concrete pads. Model Model 625L Model loops have nominal diameter three meters arrayed same manner loops. elements used where their lower noise figure advantageous, quiet sites away from urban areas (see Noise Figure Table). Model 625L pair orthogonal loops mounted common axis. With diameter 3.66 meters, largest aperture loops. Individual outputs from each loop provide bidirectional signals; outputs also combined provide omnidirectional coverage.
Power Supply Multicoupler Unit (PSM) combination power supply multicoupler unit (PSM) normally mounted rack receiver building. supplies array preamps user's coax. also "picks off" from coax distributes station's receivers number connectors (usually four) back unit. Systems without amplifiers normally retain chassis central source array's output, which include power splitters feed multiple receivers. Model Numbering System Loop elements arrayed many configurations. nomenclature describes them follows: term: term: term: term: term: number arms array element type, number loop elements each spacing between elements, meters operation mode element unidirectional, bidirectional)
Thus, array four bidirectional arms, each having eight elements spaced four meters apart would designated Model 4-612-8-4-B. This 8-direction rosette described above "Large Arrays Loops."
Plan Elevation View Model Specifications shown tables
Radiation Pattern Model 612-1 625-1 (directive gain dBi)
Plan Elevation View Model 612-1 element only Model 612-2 both elements
Specifications
Power Supply Multicoupler Unit
Frequency Range 2-32 Impedance VSWR. 1.2:1 maximum Connection located rear panel BNC-jacks Power Requirements 115/220 1.3/0.7 50-60 single phase Size 19"x3.50"x13.75" deep
Model 1-612-8-8-U
Frequency 2-16 Front-to-Back Ratio (2-16 MHz) Directive Gain
Model 612-1
Composed single loop w/amplifier power supply. Multicoupled outputs available, optionally. Frequency 2-32 Directive Gain
Bi-directional End-Fire Loop Arrays
Frequency 2-32 Polarization Vertical Directive Gain Direction Radiation Array bi-directional receive signals simultaneously from either end-fire direction Azimuth Beamwidth points Elevation Angle upper points Front-to-back Ratio minimum (4-32 MHz) Loops Array. Array Length meters feet)-612 meters (102 feet)-625 Inter-Loop Spacing. meters feet) Element Height meters inches)-612 meters (134 inches)-625 meters (174 inches)-625L Impedance (output) ohms Beam Former Output Connector. 2-type-N jacks
Noise figure (db) loop arrays (systems include amplifier noise figure)
Frequency 612-1 51.8 39.8 30.3 21.8 16.5 612-8-4-B 45.8 33.8 24.8 15.8 10.5 625-8-4-B 33.7 25.3 15.5 625L 39.3 30.8 21.7 15.0 16.3
Model 612-2
Composed single loops disposed orthogonally either individually with hybrid combiner form omni azimuthal pattern. (Supplied with amplifier power supply.) Multicoupled outputs available, optionally. Frequency 2-32 Directive Gain when individually when with hybrid combiner.
Model 1-612-8-4-U Model 1-625-8-4-U
Azimuth Elevation Directive Gain Patterns
Effective height loop arrays output
Frequency 612-1 0.75 612-8-4-B 625-8-4-B 10.8 12.1 625L
Field strength incident array required drive amplifier compression point (v/m)
Frequency 612-1 4.70 1.61 1.21 1.21 612-8-4-B 1.95 0.81 0.60 0.60 625-8-4-B 0.60 0.29 0.26 0.50 625L 1.13 0.60 0.55 1.21
Perfect ground Average ground 5mS/m,E1
612625-040201© TCI, 2001 Data specifications subject change without notice.
www.tcibr.com 47300 Kato Road, Fremont, California 94538, 824-8074 (USA) 687-6100 687-6101

Loop Arrays Easy install Easy transport Compact, low-profile Conf

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