Related Manuals for MFJ MFJ-1784
Summary of Contents for MFJ MFJ-1784
- Page 1 Giant Box Fan Antenna MFJ-1784 INSTRUCTION MANUAL ©2020 300 Industrial Park Rd. Starkville, MS 39759 P: (662) 323-5869 F: (662) 323-6551...
- Page 2 The copy of this manual provided to the customer will not be updated to reflect current data. Customers using this manual should report errors or omissions, recommendations for improvements, or other comments to MFJ Enterprises, 300 Industrial Park Road, Starkville, MS 39759. Phone: (662) 323-5869 Fax: (662) 323-6551 Business hours: M-F 8:00 AM - 4:30 PM CST.
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Page 3: Table Of Contents
1 RADIO-FREQUENCY RADIATION 2 THE MFJ-1784 2.1 INTRODUCTION ........ -
Page 4: Radio-Frequency Radiation
MFJ-1784 Giant Box Fan Portable Loop Antenna Instruction & Technical Manual RADIO-FREQUENCY RADIATION Radio-frequency (RF) radiation is one type of electromagnetic radiation. Electromagnetic waves and associated phenomena are described in terms of energy, radiation, and fields. Electromagnetic radiation is defined as waves in electric and magnetic fields moving together, or radiating, through space (Figure 1). -
Page 5: The Mfj-1784
You can place the antenna on a picnic table, wooden table or any other non-metallic convenient place, and you are ready to start operating. The MFJ-1784 requires no tuner and is self tuned across all of its rated bands with an SWR less than 1.5. The driven element is constructed from rugged aluminum sheeting. -
Page 6: Theory Of Operation
floor above ground level makes for a better portable operation experience with the MFJ-1784. At very low heights, close coupling to the ground causes detuning and losses due to the twin factors of current induced into a mirror image of the loop below the surface and the resistance of the image loop proportional to soil resistance. -
Page 7: Patterns, Polarization, And Location
MFJ-1784 Giant Box Fan Portable Loop Antenna Instruction & Technical Manual MFJ-1784 is not an option, the loop should be mounted vertically (Figure 3). 2.2.1 PATTERNS, POLARIZATION, AND LOCATION The Box Fan loop antenna can be used to provide either vertical or horizontal polarization (Figure 3). -
Page 8: Field And Null Patterns
MFJ-1784 Giant Box Fan Portable Loop Antenna Instruction & Technical Manual (a) Magnetic and electric field lines (b) Signal Nulling Figure 4: Field and Null Patterns VERTICAL POLARIZATION When the loop is oriented to provide vertical polarization the pattern is vertically polarized in line with the loop element. There will still be a large amount of horizontally polarized radiation broadside to the loop, especially if the ground under the loop is less than perfect or if the loop is placed some distance above the ground. -
Page 9: Features
MFJ-1784 a breeze SYSTEM SETUP & OPERATION Figure 5 shows a simple layout for a portable station using the MFJ-1784. Connect the controller, either the standard one or the Deluxe Loop Controller, between the radio and the MFJ-1784. Key the radio at low power ( 10W) and adjust the antenna to match using the either radio’s SWR meter or a simple one such as the MFJ-818. -
Page 10: Controls & Connections
The MFJ-1783 controller box requires an 18 VDC 500 mA, ungrounded power supply. The power jack accepts a 2.1 mm coaxial plug with the center conductor positive. -
Page 11: Tuning
The coax line should be kept as short as practical to reduce losses. Good quality 50Ω coax, such as MFJ’s Messi & Paoloni line, should be used as low-loss cable will allow longer lengths of coax to be used, increasing the standoff distance between you and the antenna. -
Page 12: Technical Assistance
MFJ Technical Service at (662) 323-0549 or the MFJ Factory at (662) 323-5869. You will be best helped if you have your unit, manual and all information on your station handy so you can answer any questions the technicians may ask. - Page 13 USER NOTES...
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