How to make an antenna to improve 4G signals in rural Kerala?

| December 31, 2025 | Amateur Radio (Ham Radio) | No Comments

In rural Kerala, geographical hurdles like dense rubber plantations and hilly terrain often weaken 4G signals. Since most Indian providers use the 1800 MHz (Band 3) and 2300 MHz (Band 40) frequencies, your DIY antenna must be tuned to these specific wavelengths. The most effective DIY design for rural areas is a Bi-Quad Antenna because it is easier to build than a Yagi and has a wide enough beam to capture signals even if your alignment isn’t perfect. Bi-Quad Antenna is two full wave quad loop antennas in front of a reflector 1/8 wavelength away. It can have a gain of about 11 dBi. Though I have mentioned my region, principle of construction should be the same for any region with similar terrain and low 4G signals.

1. Preparation & Materials

To build a Bi-Quad antenna tuned for the 1800 MHz band (common in rural Kerala), you will need:

  • Copper Wire: 2mm thick (12 or 14 gauge) solid copper wire.
  • Reflector: A flat metal sheet (aluminum or copper) or even a sturdy piece of cardboard covered smoothly with aluminum foil. Size: approx. 12cm x 12cm.
  • Coaxial Cable: RG-6 (75 ohm) or RG-58 cable (50 ohm).
  • SMA Connector: To connect the cable to your 4G router or a signal coupler for your phone.
  • Tools: Pliers, soldering iron, and a ruler.

2. The Build Process

Step A: Bending the Copper Wire

  1. For the 1800 MHz frequency, each side of the “diamond” in the quad should be approximately 41mm. That is roughly quarter wavelength for the frequency so that one quad will be a full wavelength. See the table below if you wish to construct for a different frequency band.
  2. Take a 328 mm piece of copper wire and bend it into two squares (a figure-8 shape) where each straight side is 41mm.
  3. The ends of the wire should meet in the center but not touch the other side of the loop.

Step B: Preparing the Reflector

  1. Mark the center of your 12cm x 12cm metal sheet.
  2. Drill a small hole in the center to pass your coaxial cable through.
  3. Mount the copper “figure-8” about 2 cm away from the metal plate. That is about 1/8 of wavelength for 1800 MHz. You can use a small plastic spacer to hold it at this distance.

Step C: Connections

  1. Strip the end of your coaxial cable.
  2. Solder the inner core of the cable to one side of the center gap of your copper wire.
  3. Solder the outer shield (braid) of the cable to the other side of the center gap.
  4. Ensure the copper wire is NOT touching the metal reflector plate.

3. Installation in Rural Kerala

  • Height is Key: Mount the antenna on your roof or a long GI pipe. In Kerala, getting the antenna above the “tree line” (especially coconut and rubber trees) significantly reduces signal “fade.”
  • Directional Alignment: Find the nearest cell tower. Point the flat face of your antenna directly toward that tower.
  • Passive Repeating: If you don’t have an antenna port on your phone, you can make a “passive repeater” by connecting this outdoor antenna to a second, smaller loop of wire placed behind your phone inside the house.

Frequency Reference Table for India

If you want to tune for a specific band, use these side lengths:

BandFrequencySide Length (each side)
Band 5850 MHz~85mm
Band 31800 MHz~41mm
Band 402300 MHz~32mm

Disclaimer: I have not tried it out as I am located within 100 meters of multiple mobile towers!