1 / 4

NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ

NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ. THE CONCEPT – HOW IT WORKS. TRAPS ARE PARALLEL RESONANT CIRCUITS: PARALLEL CIRCUITS EXHIBIT VERY HIGH IMPEDANCE AT THE RESONANT FREQ. THE 5 MHZ DIPOLE DOESN’T “SEE” WIRE BEYOND THE POINT OF THE TRAP.

juana
Télécharger la présentation

NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ THE CONCEPT – HOW IT WORKS • TRAPS ARE PARALLEL RESONANT CIRCUITS: • PARALLEL CIRCUITS EXHIBIT VERY HIGH IMPEDANCE AT THE RESONANT FREQ. • THE 5 MHZ DIPOLE DOESN’T “SEE” WIRE BEYOND THE POINT OF THE TRAP. • THE 3 MHZ DIPOLE “SEES” THE ENTIRE LENGTH OF WIRE. • BOTH THE COIL AND CAPACITOR CAN BE MADE FROM THE SAME LENGTH OF COAXIAL • CABLE WOUND ON A LENGTH OF PVC PIPE : • THE CAPACITOR IS FORMED BY THE CAPACITANCE BETWEEN INNER AND OUTER CONDUCTORS OF THE COAX CABLE. • THE WINDING OF THE CABLE ON THE FORM ALSO CREATES AN INDUCTANCE.

  2. NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ COAX CONNECTION DETAIL • THE COAX (RG-58/U IS WOUND ON A 1/8-IN PVC PIPE FORM 1-1/2 IN IN DIAMETER. • THE TRAP WILL RESONATE AT THE LOW END OF 5 MHZ WITH 13 TURNS OF • COAX CLOSE-WOUND ON THE FORM. • USE BRAIDED CENTER CONDUCTOR COAX VS SOLID –IT’S EASIER TO WORK WITH !

  3. NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ THE LENGTH OF A HALF-WAVE DIPOLE IS CALCULATED BY THE FORMUA: 468 LENGTH IN FT = ------------------ F (MHZ) • CALCULATE THE LENGTH OF THE 5 MHZ DIPOLE FIRST: • 468 468 • L = ------------------- = ------------------ = 86.988 OR 87 FT • F (MHZ 5.380 MHZ • CONNECT 43.5 FEET OF WIRE TO EACH SIDE OF THE CENTER INSULATOR AND • THEN CONNECT THE TRAPS. • CALCULATE THE LENGTH OF THE 3 MHZ DIPOLE NEXT: • 468 468 • L = ----------------- = -------------------- = 143.1 OR 143 FT • F (MHZ) 3.270 MHZ • SUBTRACT THE LENGTH OF THE 5 MHZ DIPOLE FROM THE 3 MHZ DIPOLE: • 143 FT - 87FT = 56 FT • ADD 28 FEET OF WIRE FROM EACH OF THE TRAPS TO THE END INSULATORS.

  4. NAVMARCORMARS COAXIAL CABLE TRAP DIPOLE FOR 3 & 5 MHZ • TRIM THE DIPOLES TO THE DESIRED CENTER FREQUENCY AND LOWEST SWR. • START WITH THE 5MHZ DIPOLE THEN TRIM THE 3 MHZ DIPOLE. • TIP: PRUNE ONLY 6 INCHES OF WIRE AT A TIME. • EXACT LENGTH DEPENDS ON MANY FACTORS: • THE QUALITY OF THE COAX USED • THE HEIGHT OF THE DIPOLE ABOVE GROUND • NEARBY OBJECTS: HOUSE, TOWER, TREES, SWING SETS, ETC.

More Related