Topband: shortcuts to GOOD 160m antennas?

R. Earle Sanders nt7y at xmission.com
Fri Aug 22 00:16:31 EDT 2003


I AM IN NO WAY CONSIDERED TO BE AN ANTENNA GURU NOR DO I CONSIDER MYSELF AS
A 160M PRO.  FROM A SHORT ACQUAINTANCE WITH TOP BAND I AM CONVINCED THAT
160M IS NOT FOR SISSIES.  IT IS A TOUGH BAND AND AN EVEN TOUGHER CHALLENGE.
ONE THING I HAVE LEARNED WHICH I THINK BEARS REPEATING FOR NEWCOMERS TO TOP
BAND.  ANTENNAS ARE THE SECRET.
  A REVIEW OF ANTENNA THEORY IS IN ORDER TO EMPHASIZE VALID POINTS ABOUT
TOPBAND ANTENNAS.

       1. BASIC CALCULATIONS SHOW THAT THE SIZE OF A SIMPLE 160M DIPOLE IS
UNWIELDY FOR
          MOST CITY LOTS.(ABOUT 260 FEET LONG)

       2. DIPOLES SHOULD BE APPROXIMATELY ONE FOURTH WAVE agl. WHICH
TRANSLATED TO ABOUT 130 FEET
          ABOVE GROUND(THAT IS A SUGGESTED MINIMUM) TOUGH CHALLENGE FOR A
CITY LOT.  AN INVERTED
          VEE FITS ABOUT THE SAME REQUIREMENTS.

       3. ANYTHING LESS THAN THIS IS A COMPROMISE.  NOT THAT COMPROMISE  IN
ITSELF IS BAD BUT
          SHOULD BE RECOGNIZED AS SUCH.  THERE ARE SOME CURRENT PRACTICES
THAT ATTEMPT TO LESSEN
          THE IMPACT OF COMPORMISE ON 160M ANTENNAS; IE, STUBS, INDUCTORS
ETC.  fROM WHAT I HAVE
          SEEN ON TOPBAND THERE IS NO COMPROMISE WITH HEIGHT ,ETC FROM THE
SO CALLED BIG GUNS.

       4. A MORE EASILY ADAPTED TO CITY LOT OR RESTRICTED SPACE IS A GOOD
SHORTENED VERTICAL.
          ANY VERTICAL NEEDS CLOSE ATTENTION TO THE BASE IMPEDANCE MATCH AND
A GOOD RADIAL
         SYSTEM. BUT FAR MORE EASILY DEALT WITH THAN A FULL SIXE DIPOLE OR
INVERTED VEE IN SMALL
         SPACE.   FORTUNATELY, I HAVE ROOM TO PLAY WITH WIRE AND VERTICALS.
MY VERTICAL IS MUCH
        BETTER IN PERFORMANCE THAN ANYWIRE ANTENNA I HAVE USED.

NT7Y, EARLE




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