THE DIPOLE ANTENNA
THE DIPOLE ANTENNA IS THE MOST WIDELY USED ANTENNA IN THE WORLD. IT'S EASE OF CONSTRUCTION AND INSTALLATION MAKES THIS ANTENNA PERFCT FOR LOW BAND COMMUNICATIONS. THE DIPOLE IS MADE UP OF TWO 1/4 WAVELENGTH METAL RODS OR OF WIRE. EACH LEG IS MEASURED BY 234/FREQUENCY IN MHz. TOTAL LENGTH IS 468/FREQUENCY. THIS IS MEASURED IN FEET. THE DIPOLE YIELDS A GAIN OF 3db OVER ISOTROPIC SOURCE. THIS IS KNOWN AS UNITY GAIN. THE DIPOLE HAS AN IMPEDANCE OF 36 OHMS IN FREE SPACE. WHEN CONNECTED TO A COAX CABLE IT WIL PRODUCE 50 TO 72 OHMS IMPEDANCE.
THE INVERTED V ANTENNA
THE INVERTED "V" ANTENNA, OR THE INVERTED DIPOLE ANTENNA IS ONE THAT LENDS ITSELF WELL TO BOTH HORIZINTAL & VERTICAL POLARITY AT THE SAME TIME. THE INVERTED V PRODUCES AN OBLONG RF PATTERN MUCH IN THE SAME SHAPE OF AN EGG. WITH THIS ALMOST OMNI DIRECTIONAL ANTENNA, ONE CAN OBTAINREMARKABLE RESULTS OF BOTN TRANSMISSION AAND RECEPTION. LIKE THE DIPOLE, YOU WILL HAVE A GAIN OF 2.17dbi.
THE INVERTED V IS VERY POPULAR AMOUNG HAM RADIO OPERATORS AS TO IT'S EASY CONSTRUCTION AND USE. THE INVERTED V TAKES UP VERY LITTLE SPACE AN PROVIDES LOE SWR's.
IDEA FOR HOOKING UP YOUR COAX TO A HORIZONTAL DIPOLE OR INVERTED V ANTENNA
FIRST OF ALL ON THE END OF YOUR RG-8/U COAX YOUR GOING TO ATTACH TO THE DIPOLE. YOU NEED TO STRIP BACK ABOUT 6 INCHES OF THE OUTER JACKET. THIS WILL EXPOSE THE BRAIDED SHIELD WIRE. USING A SMALL BLUNT OBJECT YOU NEED TO SEPARATE THE BRAID TO FORM A SINGLE LINE AFTER IT'S TWISTED TOGETHER.ONCE YOU HAVE THIS DONE TIN THE END OF IT AND COVER 5 INCHES OF THE BRAID WITH SOME HEAT SHRINK TUBING LEAVING 1 INCH EXPOSED TO WRAP AROUND THE FEED POINT ON YOUR INSULATOR
NEXT CUT BACK THE INSULATION AROUND THE CENTER CONDUCTOR ABOUT 5 INCHES. YOU CAN COVER ABOUT 4 INCHES BACK UP WITH THE HEAT SHRINK TUBING LEAVING 1 INCH EXPOSED TO WRAP AROUND THE FEED POINT ON YOUR INSULATOR. THIS IS WHAT IS KNOWN AS A DIRECT FEEDLINE ATTACHMENT TO YOUR ANTENNA. IT'S SIMPLE AND EASY ONCE YOU GET THE FIRST ONE DONE. HI HI! BELOW ARE SOME ROUGH GRAPHICS OF WHAT AND HOW I ATTACHED MY FEEDLINE TO THE WIRE DIPOLE USING 1 INCH I.D. PVC PIPE AS THE INSULATIOR.
I USED 1 PC 8 INCHES LONG WITH A 1/4 INCH HOLE DRILLED THROUGH THE PVC TO ALLOW ME TO USE A STAINLESS STEEL BOLT AND NUT FOR ATTACHING THE COAX FEEDLINE. ON THE TEMINATING END OF THE WIRE I USED 2 PCS OF PVC 4 INCHES LONG WITH AGAIN THE 1/4 INCH HOLES DRILLED THROUGH FOR THE ANCHOR ROPE TO TIE IT OFF WITH AND THEN ANOTHER PAIR OF BOLTS AND NUT TO TERMINATE THE WIRE INTO THE INSULATOR WITH.
THE DELTA QUAD LOOP
THE DELTA QUAD LOOP ANTENNA IS COMPOSED OF A SINGLE WIRE THAT IS A FULL WAVELENGTH LONG. EACH SIDE OF THE LOOP IS 1/3 WAVELENGTH. THE TOTAL LENGTH IS CALCULATED BY 984/FREQUENCY FOR A SINGLE FREQUENCY AIN 1005/FREQUENCY FOR A MULTI-BAND. EACH SIDE IS 328/FREQUENCY. THE QUAD PROVIDES A GAIN OF 5.7dbi, AND PRODUCES A FIGURE EIGHT PATTERN MUCH LIKE THAT OF A HORIZONTAL DIPOLE. THE DELTA QUAD PROVIDES A LOW ANGLE LOBE FOR FINE DXing. NO LINE TUNER SHOULD BE NEEDED EXCEPT WHEN USING A MULTI-BAND UNIT.
THE 3/4 WAVE VERTICAL
THE 3/4 WAVE VERTICAL LIKE A DIPOLE ANTENNA PRODUCES UNITY GAIN, OR 6dbi. AT THE BASE OF THE 3/4 WAVE VERTICAL THE IMPEDANCE IS 52 OHMS. THE HORIZONTAL GROUND RADIALS ACT AS MIRRORS IMAGES OF THE VERTICAL ELEMENT. THE 3/4 WAVE HAS ONE LOWER LOBE AND ONE HIGHER LOBE OF RF RADIATION. THE GROUND RADIAL LENGTH IS FOUND AT 240/FREQUENCY IN MHz. THE 3/4 WAVE VERTICAL IS MOSTLY USED FOR DXing AS IT HAS TWO LARGE RF LOBES. AT SHORT WAVE FREQUENCIES THIS OFTEN PROVES TO BE OF GREAT BENEFIT. THE VERTICAL PROVIDES A TRUE OMNI DIRECTIONAL RF PATTERN. THERE ARE NO SPECIAL DEVICES TO MAKE THIS ANTENNA FUNCTION TO IT'S FULLEST.
THE 3/4 WAVE ZEPA SLOPER
THE 3/4 WAVE ZEPA SLOPER IS A SLIGHT CHANGE TO THE ORIGINAL 5/8 WAVE ZEPA DESIGN. THE ORIGINAL DESIGN REQUIRES A LINE TUNER OR BASE TUNER TO LOWER SWRs AS WITH ALL 5/8 WAVE DESIGNS. THE 3/4 WAVE DESIGN PRODUCES THE SAME SUPER LOW ANGLE RADIATION PATTERN AS THE 5/8 DESIGN, BUT ADDS AN ADDITIONAL HIGH LOBE WHICH YIELDS FANTASTIC LOCAL COVERAGE AS WELL AS SURPRISING DX.
THE ZEPA WAS USED ON THE OLD GERMAN AIRCRAFT FOR IT'S LONG RANGE AND DEPENDABLE COVERAGE CAN NOW BE USED AT HOME. THE 3/4 WAVE UNIT EMPLOYEES LOW SWR AT THE FEED POINT
THE LONG WIRE ANTENNA
THE LONG WIRE ANTENNA WAS ONE OF THE FIRST SHORTWAVE ANTENNAS EVER MADE. IT IS KNOWN FOR IT'S SHARP BI-DIRECTIVITY OFF THE ENDS. GAIN IS ABOUT 4db OVER A STANDARD DIPOLE ANTENNA. THE DRIVEN ELEMENT IS BEST WHEN CUT TO 1-1/4 WAVELENGTH.
THE ANTENNA PROGRAM ANTENNA 98 I USED CAN BE LOADED FROM THIS LINK. CLICK ON THE LINK HERE AND SAVE THE FILE TO YOUR DESKTOP OR INTO IT'S OWN FOLDER. YOU WILL NEED WINZIP TO UNZIP THIS FILE. ANTENNA 98 IS A DOS PROGRAM AND RUNS WELL FROM A DOS WINDIOW FROM WITHIN WINDOWS. NOTE I DID NOT WRITE THIS PROGRAM SO USING IT IS AT YOUR OWN RISK. I HAVE HAD NO PROBLEMS USING ON MY MACHINE BUT, I CAN'T CLAIM THAT WITH YOUR MACHINE...73 AND GOD BLESS
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