How to Build Your Own High Gain VHF TV Antenna

Written by adam quinn
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How to Build Your Own High Gain VHF TV Antenna
Replace your rabbit ears with a high-gain VHF antenna. (Comstock/Comstock/Getty Images)

If you live in an area with poor television reception, but would like to receive free digital TV broadcasts, a high-gain rhombic antenna may be an effective solution. A rhombic, or diamond-shaped, antenna can be built to receive distant and weak VHF TV signals. The design can be mounted to a ceiling or hidden in the crawl space, minimising unsightly wires in your living room. This versatile rhombic design may partially receive UHF programming as well.

Skill level:
Moderate

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Things you need

  • Twin-lead cable, 300-ohm, 30 feet long
  • Matching transformer, 300-ohm to 75-ohm
  • Coaxial cable, 75-ohm with connectors, 10 feet long
  • 2 resistors, 1/4-watt, 470-ohm
  • 8 wire caps
  • Terminal strip, 2-position, dual-row
  • 4 wood screws
  • Thumbtacks
  • Screwdriver
  • Protractor

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Instructions

  1. 1

    Cut the twin-lead cable into four 87 1/2 inch lengths. Strip 1/2 inch of insulation from the ends. Attach two lengths together using wire caps, forming a 175-inch cable. Do this procedure with the remaining two lengths as well, being careful not to cross the wires. You should have two 175-inch cables, each with a node in the middle where the wires are capped.

  2. 2

    Twist the wired pairs together at one end of each 175-inch cable. With the terminal strip rows oriented vertically, attach a twisted wire end to the upper right and left screws. Secure the fork terminals of the transformer to the lower screws. This will be the feed line end of the rhombic antenna.

  3. 3

    Connect the free ends of the 175-inch cables together by attaching a resistor across each wire using caps. Do not cross the wires. This will be the terminal end of the antenna.

  4. 4

    Spread the antenna out, forming a diamond shape. Tack the antenna to the ceiling, using extra tacks near the corners to relieve stress from the capped wires. The feed line and terminal corners should form 50-degree angles, and the node corners should form 130-degree angles. Screw the terminal strip to the ceiling once the antenna has been mounted.

  5. 5

    Attach the antenna to your TV's external antenna jack using the coaxial cable.

Tips and warnings

  • Mount the antenna with the feed line corner near the TV.
  • If possible, orient the antenna so the 50-degree corners point in the direction of the TV station.

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