How to Build a High Performance 2 Coil Rod Antenna

Making a 2 Coil Rod Antenna for Improved Reception

Having a good antenna is crucial for getting the most out of your radio, television, or other wireless equipment. While simple single wire antennas work fine, you can improve your reception by building a more advanced design. One great option is making a 2 coil rod antenna, which can significantly boost the performance of your system.

How Rod Antennas Work

Rod antennas, also known as monopole antennas, consist of a single conducting rod or wire mounted vertically. They function by resonating at particular frequencies based on their length. The rod or wire acts effectively as a quarter wave antenna, meaning its electrical length is one quarter the wavelength of the signal you want to receive. This allows it to convert the electromagnetic waves into alternating currents that can be processed by your receiver.

Adding more conducting elements allows a monopole antenna to resonate at additional frequencies. A 2 coil design takes advantage of this by having two separate coils spaced along the rod, enabling it to receive signals more efficiently across a wider range of frequencies.

Choosing Materials for Construction

When building your 2 coil rod antenna, you'll need to select suitable materials to make the coils and main rod or pole. Here are some good options to consider:

• Copper wire - For the coils, multi-stranded copper wire works very well, ensuring good conductivity.
• Aluminum tubing - An aluminum rod or tube makes a lightweight and corrosion resistant main pole.
• PVC - For better weather protection, PVC tubing can cover the coils and insulate the antenna.
• Wood dowel - A fiberglass or wooden rod also works for the main support in some cases.

The thickness of the wire and tubing used will depend on the size and particular design of your antenna. Heavier gauges are better for larger, more robust outdoor antennas.

Designing and Winding the Coils

The specific dimensions of the coils will determine the antenna's frequency response. Some design parameters to consider are:

• Coil diameter - Larger coils resonate at lower frequencies.
• Number of turns - More turns increases the inductance for lower frequencies.
• Coil spacing - Wider spacing broadens the overall frequency range.
• Coil position - Placing coils symmetrically along the rod provides the widest response.

To wind your coils, wrap the wire neatly around a cylindrical object like a PVC pipe or wooden dowel. Keep the turns spaced evenly without gaps. Calculate the number of turns required using antenna design formulas or guides. Remove the finished coils from the winding tool and secure them in place on the main rod using tape or clamps.

Connecting and Installing Your Antenna

Once assembled, your 2 coil rod antenna will need to be connected to your receiver and installed properly for best performance. Here are some tips:

• Solder wires to each coil end and connect to 50 ohm coaxial feedline.
• Use standoff insulators to prevent shorts between coils and pole.
• Mount antenna vertically on a roof or pole at least 10 ft. high.
• Aim directional antennas towards station/transmitter location.
• Seal and weatherproof connections to prevent corrosion and shorts.

Raising your new 2 coil antenna higher always improves reception. Point directional models towards the desired station or transmit site for optimal gain. Take care to securely install guy wires if mounting the antenna on a roof or tower.

Tuning and Adjusting Your Antenna

Once installed, check the antenna on your desired frequencies using a standing wave ratio (SWR) meter. Trim the coil ends incrementally to tune out any high SWR readings. If needed, change the coil winding spacing or add matching components like a gamma match until you achieve an optimal SWR of under 2:1.

Your 2 coil rod antenna should now boost your reception and performance. Enjoy exploring more stations and channels with your improved wireless system. With some experimentation, this versatile monopole design can be adapted to receive signals from AM/FM radio all the way up to TV broadcasts.

FAQ

What are the benefits of a 2 coil antenna?

A 2 coil antenna provides wider frequency coverage compared to a single coil or wire antenna. The dual resonant coils enable improved reception across AM, shortwave, FM radio, and lower TV bands. It also allows for adjustments to fine tune reception on specific frequencies.

How do I calculate the size of coils needed?

Use antenna design formulas based on the desired reception frequencies to calculate total wire length for each coil. For the lower frequency coil, make it physically larger with more turns of wire. The higher frequency coil should be smaller with fewer turns. Adjust from there to tune the antenna.

What type of wire is best for the coils?

14-18 gauge multi-stranded copper wire works very well for the coils. It is flexible and easy to wind while still maintaining good conductivity. Enameled copper wire helps minimize corrosion and is durable when exposed to weather.

Where is the best place to install my antenna?

For optimal reception and range, install your antenna on a roof or pole at the highest elevation possible. Place it above nearby trees or buildings and orient directional models towards the desired station or transmit source.

How can I protect my 2 coil antenna from weathering?

Use weatherproof connection boxes and coaxial cable. Cover the coils in PVC tubing or wrap with electrical tape. Seal any openings into the support pole and treat exposed wires with corrosion inhibiting gel or sprays. Periodically check for water damage or oxidation.

FAQs

What type of mount should I use for my antenna?

Use a sturdy non-conductive mount to hold your antenna pole firmly in place. Fiberglass mounting brackets or PVC mounts work well. Ensure it can support the height and weight of the antenna during high winds.

How high should I place my 2 coil antenna?

For best results, install it as high up as possible - at least 30-40 ft is recommended. Greater height allows clear line of sight over obstructions and improves the antenna's reception range.

Can I connect multiple antennas to my receiver?

Yes, you can combine several antennas into an array using an antenna combiner module. This allows you to stack different antennas specialized for different bands for improved overall coverage.

Should I ground my antenna?

Properly grounding the antenna mast and mount can help protect against lightning strikes. Use thick ground wires connected to ground rods around the base. Ensure your coax shield is also grounded.

How can I improve directionality?

Adding a passive reflector rod or coil behind the antenna helps increase directionality for pointing the antenna. Corner reflectors and parabolic backplanes can further enhance directional gain.