Anti-Jamming Antenna

Short Wave radio
Short Wave radio

The method below describes a way to reduce interference with our signal to make it easier to hear RFA broadcasts via shortwave radio.

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I. Materials

  1. One shortwave radio with rod antenna (A).

  2. One (additional) rod antenna (or metal wire 2 cm shorter than the radio antenna) (B).

  3. One non-conductive, dry board (C) big enough to fit the radio and metal sheets (about 30cm x 60cm) plywood or a similar material is OK.

  4. Four cup hooks (D).

  5. Two rubber bands or string (E).

  6. Two sheets of tinfoil/aluminum foil (or other conductive metal sheet) (F). The sheets should be larger than the height x length of the radio (see photo).

  7. One small wood block (about 4x4x2cm) (G).

  8. Two small wires (15 cm each) long enough to connect the antenna to the metal sheets (H).

  9. Two small screws (I) for connecting the wires to the two metal sheets.

II. Construction

  1. Fasten the two sheets of tinfoil (F) onto the board (C), as shown in the picture. They should be at least 2 cm apart (they should not touch).

  2. Install the four cup hooks (D) on each side of the tinfoil that you will put your radio (A) on (they will be used to hold the radio down when rotating the board for best reception).

  3. Drill a hole in the small wood block (G) approximately the size of the bottom diameter of the antenna. Insert the additional antenna and wrap one of the wires (H) around the bottom of the antenna. Ensure the wire and antenna make a firm electrical connection. Connect the other end of the wire to the tinfoil the radio will be placed on with one of the small screws (I). Fasten the small wood block with antenna onto the board as shown on the picture (use glue/screws/ or nails). (You may use a wire to replace the additional antenna. Tape the wire to a wood dowel and mount the dowel to the wood block. Connect the wire antenna to the tinfoil (F).) D. Use the second screw(I) to fasten the second wire(H) onto the second sheet of the tinfoil (F) and connect the other end of the wire onto the radio's built in antenna.(tightly wrapping the wire around the radio's antenna is fine)

  4. Place the radio on the tinfoil, as shown in the picture, and use the rubber bands or string (E) to fix the radio onto the board. At this point, both antennas should be vertical to the board. The radio's antenna should be extended fully while the second antenna should be slightly lower that that of the radio's. Your system is ready to use.

III. Operation

  1. With the radio mounted in position on the board you should move to a relatively open area, near a window, on a balcony, or even outdoors.

  2. Tune the radio to the desired frequency. Rotate the board to different angles until you find the best reception. Do not touch the tinfoil, radio, or antennas when rotating the board. Keep the board away from your body to limit the effects your body will have on the radio's reception. What you are doing by rotating the board is trying to block the interfering signal while keeping the desired signal strong.

  3. If you cannot get good reception, turn the radio's antenna to different angles and continue to rotate the system until you have the best reception. If one frequency doesn't work, change to a different frequency and repeat the above steps. Radio Free Asia broadcasts on a number of frequencies from various locations.