How to Build a UHF Rhombic Antenna

Written by adam quinn
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How to Build a UHF Rhombic Antenna
Watch free HDTV broadcasts using a homemade rhombic antenna. (Jupiterimages/Polka Dot/Getty Images)

A UHF rhombic antenna can boost weak and distant TV signals, providing enhanced reception to your digital or high-definition TV. The diamond-shaped rhombic antenna's high-gain design provides improved signal quality, enabling you to watch local TV programming without a costly cable TV subscription. This type of antenna can be mounted to your ceiling or in your crawl space, eliminating unsightly antenna rods and wires.

Skill level:

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Things you need

  • Twin-lead cable, 300-ohm, 34 feet
  • Coaxial cable, 75-ohm with connectors, 10 feet
  • 2 resistors, 1/4-watt, 470-ohm
  • Matching transformer, 300-ohm to 75-ohm
  • Terminal strip, 2-position, dual-row
  • 4 wood screws
  • 8 wire caps
  • Thumbtacks
  • Screwdriver
  • Protractor

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  1. 1

    Cut the twin-lead into four 100-inch lengths. Remove 1/2 inch of insulation from each end of the four cables. Connect two lengths of cable together using wire nuts, taking care not to cross the wires. Connect the remaining two lengths of cable together in the same way. You should have two 200-inch lengths of cable, each with a middle node.

  2. 2

    Twist the twin-lead wires together at one end of each 200-inch cable. Orient the terminal strip rows vertically, and attach one twisted cable end to the upper right screw, and one to the upper left. Attach the terminal forks of the transformer to the lower screws. This will be the feed line corner of the antenna.

  3. 3

    Connect the free ends of the twin-lead cables together with resistors and wire caps. One resistor should span across each wire connection, forming the terminal corner of the antenna.

  4. 4

    Spread the antenna out to form a diamond shape. Hang the antenna to the ceiling using thumbtacks. Adjust the antenna corners so the feed line and terminal corners are at 50-degree angles, and the side corners are at 130-degree angles. Use extra tacks around the corners to take the strain from the wire cap connections.

  5. 5

    Fasten the terminal strip to the ceiling using screws, once the antenna has been properly aligned.

  6. 6

    Connect the antenna to the external jack of your TV using the coaxial cable.

Tips and warnings

  • Mount the antenna to the ceiling with the feed line corner oriented near the TV.
  • If possible, orient the feed line and terminal corners in the direction of the TV broadcasts.

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