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ANTENNAS & GROUNDING SYSTEMS

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Lightning Protection 

For Amateur Radio Station's Equipment &
Creating an Effective Ground System
By Ron Block KB2UYT

Published in QST Magazine June, July & August 2002
(External Links)

PART 1       PART 2       PART 3


 

Are you looking for an inexpensive wire antenna that makes possible HF operation on all bands 10M through to 80M with wide bandwidth?

If yes, you may want to consider putting up this Delta Loop like Elizabeth, VE7TLK did on her single residential lot, with the help of amateur radio friends. Antenna apex is up approximately 82' tied to a cedar tree, while the two corners are tied to a shorter tree 25' high and a carport roof.

This Delta Loop is a three-sided antenna suspended high in the air by vertical supports, such as tall evergreen trees. Recommended height is 40 feet or more at highest point, but higher is better. It's one feed line eliminates the need for multiple antennas to cover the HF bands.

The Delta Loop's feedpoint is located near one of the bottom corners providing a slight increase in gain and easy access when maintenance is required.

Homebrew Antennas - Diagram

The radiating element or wire position in relation to the ground determines polarization. If the wire is parallel to the ground, it radiates horizontally. If the wire is perpendicular to the ground, it radiates a vertical wave. If the wire is slanted, it radiates waves, which have both horizontal and vertical qualities.

Length (ft.)       =       1005
--------------------------------------------
                                f (MHz)

Therefore, length of wire needed for an 80M loop antenna is:

Length (ft.)       =       1005     =       272 feet
--------------------------------------------
                                3.7MHz

  • Copper Stranded Wire #12
  • 4 ceeramic or glass insulators (apex, two corners, and at feedpoint)
  • RG58 or mini RG8 Coax (50 ohm) Calculate length from feed line to radio room plus a little extra.
  • PL259 Connector (UHF male) - for end of coax which connects to radio.
  • Support rope for corners and apex.
  • Roll of coax seal to wrap.
  • Polyester braided rope (3/8") needed for halyard and support ropes.

  • Draw to scale diagram of antenna and all supports with dimensions on lot.

  • Measure and cut wire length for antenna allowing 1' extra for securing insulators. Careful not to bend wire.

  • Lay the wire on the ground so that the sides can be measured and the insulators fixed to the apex and corners. To fix insulator cut a short piece of wire and twist it around the antenna wire for about 4" on one side and then cross over insulator end and repeat 4" up the other wire. This adds strength to the corners and apex ands keeps insulators in place when raising antenna.
  • Cut three pieces of support rope to clear and free antenna corners and apex from trees/buildings, etc. Connect ropes to the three insulators.

  • Feedpoint connection wavelength from bottom corner. (See diagram) With a sharp knife, carefully strip back (not cut) 3" of the exterior black jacket from one end of the 50 ohm coax being careful not to score the braid underneath. Pull the braid gently a part in one place and pull out the inner dielectric containing the center conductor. The coax is now split in two. Expose the center conductor by carefully cutting off 1" of the inner dielectric which is covering the center conductor.

  • Each wire end is then threaded through the closest insulator hole and then tightly twisted around antenna wire on that end. This is also repeated on the other end of the same insulator using the other antenna wire. Wrap prepared coax end around the middle of the insulator and secure with a clamp.

  • Once this is done and the materials have been cleaned well, solder one of the #12 gauge copper wires to braid and the other to the center conductor. To avoid water and contamination in the feed line, the antenna end of the feed line must be adequately covered with coax seal . Remember, the feed line connection at the center insulator should not be done until after the antenna wire has been tied securely to the insulator.

  • Construct a 1:1 broadband balun. Wind or coil a length of coaxial feed line for 6-8 turns near point of connection and secure with electrical tape. Lengths are not critical. Diameter of coils approximately 8".

  • Pull the antenna wire carefully up in the air by pulling down on the rope end which will eventually be tied to the limb of the tree. Once desired height of highest corner or apex has been reached, tie rope to limb near ground and within reach by a ladder.

  • One of the two remaining insulators will have its rope now tied to the second tree (or other support) which also has a collar but no pulley. This insulator and the previous one are counterweighted (halyard) and allowed to move freely.

  • The delta loop is now ready to be raised using the pulley on the halyard at the top of the tree or pole. Once the apex is fastened at the correct height proceed to fasten securely the corner ropes to their tie supports.

  • Install the PL259 (UHF male) Connector on end of coax feedline in radio room. An adapter is available if using the smaller RG-58 size coax. Connect to transceiver and test for SWR.

Introduces slack so that during high wind conditions the wire loop can move, thus reducing stress on wire avoiding breakage. See directions for making halyard.


  • Bucket (with several holes on bottom) with handle plus counterweight weighted with bricks or sand and rocks.


  • One pulley large enough for line to run through freely keeping in mind that rope can swell when wet. Buy a fast-eyed brass or bronze marine type pulley.


  • Polyester braided rope (3/8") needed to go up and down full length of tree trunk from collar to ground. Allow for extra to tie around lower limb and to raise antenna without running out of rope.


  • Make a trunk collar to protect bark of tree. This is done by threading a short piece of rope through an old hose or other soft tubing, the diameter of the trunk, where the collar will be positioned up high on the tree. Thread the pulley onto collar rope where the two ends of collar will meet together and tie securely. Only an experienced tree climber, with safety climbing equipment, should do the climbing.


  • While climber is up on the tree have him take one end of the long rope and feed it through the pulley. As he comes down he can pull that end down with him to ground level. Do not cut rope yet until after the antenna has been raised up, otherwise you may find yourself with too short a rope.


  • One end of rope will be tied to the weighted bucket handle and the other end tied tightly to a low limb within your reach. Bucket should be suspended about six feet from ground floating freely. The antenna wire at this point is still lying on the ground.


  • Just before the antenna wire is ready to be raised, tie the appropriate support short rope to the insulator at the apex of the antenna to the halyard rope's mid-point. This rope enables the wire to position itself away from tree branches.


  • Raise the apex of the antenna by pulling on the rope without the bucket tied to it to the desired height. Then tie rope securely to one of the lower limbs within reach.

Click on external links provided at top of this web page to read KB2UYT articles!

Once your station and antennas have been properly grounded, take the next step and operate DX!



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