A N T E N N A RESEARCH

Transcription

1 Our low profile MLA series Miniloops and very low profile MLH series half loops are high power communications antennas. These antennas are designed for installation in virtually any environment, especially those where space is limited. The MLS Series Miniloop Antennas are designed for special purpose applications which require narrow instantaneous bandwidth and the smallest possible size, but radiation characteristics comparable to a halfwave dipole. The MLS series antennas are sufficiently small to be utilized in many locations otherwise rendered impossible by the size of more conventional antenna systems, while also exhibiting excellent null characteristics for simple direction finding applications. MLA-1/E ON A VEHICLE The Miniloop has an almost hemispherical overhead radiation pattern, allowing excellent skywave communications at all frequencies in the operating band. Its performance is particularly good for shorthaul communications where high take-off angles are necessary. Miniloops are practically ideal as colocated antennas operating at slightly different frequencies. Their relatively narrow instantaneous bandwidth, broadside nulls, and polarization characteristics are important factors in minimizing interference. MLH series HF band tuned loop antennas are ideally suited for hardened site applications. The antenna can be recessed into a cavity with a cover such that there is little or no exposure above ground. Miniloop antennas can be mounted on vehicles for ground wave direction finding by rotating the loop until its null points toward the target transmitter. An MLA Series Miniloop antenna system is supplied with the basic loop antenna, a vertical mast, a bolt-down base, and a rack-mountable tuning unit. A hinged base/mast assembly is available for transporting the loops in a flat position on a vehicle without disassembling the loop. The MLH-324 or MLH-2/D antenna system is supplied with the basic half-loop antenna, bolt-down base plate, and a rackmountable tuning unit. Auto-tuned Miniloop systems include the MDT-1./A automatic digital tuner, which provides hands-free operation and transmitter interlock protection. The MDT Tuner reduces the full range tuning time to less than seconds. MLS antennas are designed to be tuned to the desired frequency of operation by the use of a small fiberglass tuning tool. Only a single tuning adjustment is required to resonate the antenna at any frequency within its band of operation to a SWR not exceeding 2 : 1. Pretuned loops such as our MLS-47 are designed for single frequency applications where the signal to noise ratio is critical. MLA-11 Phone: z Fax: z z sales@ara-inc.com

2 SPECIFICATIONS: HF MINILOOPS POLARIZATION: Vertical on horizon, horizontal overhead, and slant elsewhere PATTERN: Figure-of-eight at elevation angle Omni directional above 2 NULL DEPTH: 2 db GAIN: See Graphs 4 IMPEDANCE: BANDWIDTH: POWER: CONNECTOR: WIND: ohms, nominal See graphs 1 kw cw, when tuned Type N female mph., mph with 2 inches radial ice AUTO-TUNED MINILOOP ANTENNAS* MLA-11 MLA-217 MLA-324 MLH-324 FREQUENCY (MHZ) VSWR (MAX.) 1. : 1 1. : 1 1. : 1 2 : 1 TUNING TIME seconds max. transmit, 2 seconds max. receive LOOP SIZE ' H x 7' W ' H x 7' W 3'H x 4.' W 3"H x 73"W x 37"D OVERALL HEIGHT 12' 12' ' 3" WEIGHT (LBS/KG) 2 / / / 98 / 18 * Receive-only versions available. To order, add subscript R to the model number. REMOTE TUNED MINILOOP ANTENNAS MLA-1/E MLA-1/D MLA-2/D MLA-2/R MLH-2/D FREQUENCY (MHZ) VSWR (MAX.) 2 : 1 2 : 1 2 : 1 2 : 1 2 : 1 TUNING TIME 2 minutes max, with preset channels available LOOP SIZE (H X W) ' x 7' ' x 7' 3' x 4.' 3' x 4.' 3' x 4.' OVERALL HEIGHT 12' 12' ' ' 3" WEIGHT (LBS/KG) 2 / / / / 98 / 18 OPTIONS: 1) Antenna Rotator 3) Ground Plane (MLH) ( 12 ft. x 14 ft. ) 2) ' rf cable 4) Hinged base for tilting the loop MINILOOP DIGITAL TUNER MODEL MDT-1./A The Miniloop Digital Tuner (MDT) fully automates tuning of ARA Models MLA-11, MLA-217, and MLA- 324 Miniloop antennas, with a - second maximum tuning time when transmitting, and a 2 second maximum tuning time when receiving. Internal switches set during calibration select the specific Miniloop model number. The MDT is supplied with all MLA series auto-tuned Miniloop antennas. The MDT-1.A is available with a fast-tune option for applications such as channel scanning and automatic link establishment (ALE). A computer controlled matrix (HP 3488A or equivalent) and associated software enables a Miniloop antenna to tune in one second or less. The Miniloop Digital Tuner has four modes of operation, namely Transmit, Receive, Calibration, and Diagnostics. A detailed description of each mode is available upon request. US Patent No.,22,847 Phone: z Fax: z z emc@ara-inc.com

3 ... A ntenna Research MODELS MLA-324, MLA-2/D, MLA-2/R 2 At Standard Mast Height Above a Good Ground Power Gain (dbi) - 3 db Bandwidth (khz) E = [COS 2 θ COS 2 φ + SIN 2 φ] ½ COS ( βhcos θ) where H = HEIGHT ABOVE GROUND PLANE β = 2π/λ λ = WAVELENGTH = /f MHZ meters = 984/f MHz feet SMALL ARROWS SHOW DIRECTION OF E-FIELD frequency - MHz Fr Z TRACES OF UNIT SPHERE 18 ZENITH 4 ELEVATION 2 4 E 6 9 Y 27 LOOP RELATIVE VOLTS 9 X 3 -DIMENSIONAL REPRESENTATION OF PATTERN RELATIVE AMPLITUDE PATTERNS AT VARIOUS ELEVATION ANGLES Phone: z Fax: z z sales@ara-inc.com

4 3. Antenna on ground plane and with feet of RG rf Cable. SWR db Bandwidth (khz) Power Gain (dbi) MLH-324, MLH-2/D MLH-324 HINGED BASE FOR MLA LOOPS Phone: z Fax: z z emc@ara-inc.com

5 A N T E N N A MLA-11 AND MLA-1/E At a standard Mast Height Above a Good Ground MLA-11 AND MLA-1/E Frequency MHz 2 1 MLA-217 AND MLA-1/D At a standard Mast Height Above a Good Ground MINILOOP ANTENNA UPGRADE KITS Our UGK series Miniloop Upgrade Kits contain all the necessary parts and hardware for converting a remote tuned HF Miniloop Antenna System to the equivalent of automatic tuned models MLA-11, MLA- 217, MLA-324 or MLH-324 Miniloop antenna systems (see conversion chart). The upgraded antenna exhibits a lower VSWR than the older model, due to a new rectangular Feed Loop design. A new highspeed tuning capacitor and automatic digital tuner reduce tuning time to a maximum of seconds in transmit mode, and 2 seconds in receive mode. A Miniloop upgrade kit (UGK) comprises a rectangular feed loop, a digital tuner, a high-speed tuning capacitor assembly, cables with connectors and a complete technical and installation manual. MINILOOP CONVERSION CHART OLD SYSTEM FREQUENCY RANGE NEW SYSTEM UPGRADE KIT REQ'D MLA-1/E MHz MLA-11 UGK-11 MLA-1/D MHz MLA-217 UGK-217 MLA-2/D MHz MLA-324 UGK-324 MLH-2/D MLH-324 UGK-324 Phone: z Fax: z z emc@ara-inc.com