DIY 9 Element VHF / UHF Dual Band Ham Radio Antenna

Building your own VHF-UHF antenna can be a rewarding project, especially for ham radio enthusiasts and hobbyists looking to enhance their communication capabilities. A 9-element antenna offers a good balance between size and performance, making it ideal for various applications, from local communications to listening to distant stations. In this guide, we’ll break down the steps to construct your very own 9-element VHF-UHF antenna.

Understanding the Basics

Before diving into the construction, it’s essential to understand what a 9-element antenna entails. Typically, this type of antenna consists of multiple directors, a driven element, and a reflector. Each element plays a crucial role in focusing the signal and improving gain. The 9-element configuration can significantly enhance your range and clarity when transmitting or receiving signals in the VHF (144-146 MHz) and UHF (434-438) bands.

I referred to the DIY guide at https://www.qsl.net/dk7zb/Duoband/4+5_2m-70cm.htm to build my own dual-band antenna. It features a total of 9 elements: 5 elements for the 2-meter band (VHF) and 4 elements for the 70cm band (UHF). The radiator elements serve as common elements for both bands.

Materials You’ll Need

For this project, gather the following materials:

• Aluminum or copper tubing (for the elements), I used 10mm aluminium pipe as a reflector and director element. For Radiator element i used 12mm pipe.
• A sturdy boom (PVC or wood or Aluminium), I used square aluminium with 3mm thickness (a bit heavy)
• Coaxial cable (RG58 – for making ballun for dual band yagi.)
• Antenna connectors (SO239)
• An SWR meter (for tuning)
• Mounting hardware
• Tools: drill, saw, measuring tape, and a soldering iron

Step-by-Step Construction

1. Cut the Elements: Start by measuring and cutting the aluminum or copper tubing into lengths suitable for the VHF-UHF frequencies you intend to use. The driven element typically measures slightly longer than the directors, while the reflector is slightly longer than the driven element.
2. Assemble the Boom: Secure the cut elements to the boom, ensuring they are spaced evenly. The exact spacing will depend on your design; usually, directors are spaced closer together than the reflector.
3. Connect the Driven Element: Solder the coaxial cable to the driven element. Make sure to connect the center conductor to one side of the driven element and the shield to the other side.
4. Mounting: Use mounting hardware to secure the antenna to a stable base. Ensure that it can withstand outdoor conditions if you plan to install it outside.

In Surat, I found suppliers for aluminum pipes and boom materials, but they only sell entire pipes that are 12 feet long. If I were to construct a single antenna, there would be significant waste. To minimize this I plan to build 3 antenna and help other ham with it. I used online tools to plan for three antennas, allowing me to order the materials accordingly with the minimum waste. For the mounting claims, I sourced from suppliers on IndiaMART – Jitendra Shah from Ketan Industrial Works for his contact details you can cotanct me. Here’s a Google Drive link to my plan for three Yagi dual-band antennas. Additionally, I built a balun using a 1/2-inch PVC pipe with 8 turns of RG58 coaxial cable.

Tuning Your Antenna

Once your antenna is assembled, it’s crucial to tune it for optimal performance. Using an SWR meter, connect it to your radio and measure the standing wave ratio. Adjust the lengths of the elements as necessary to achieve the best SWR reading. This step ensures efficient power transfer and minimizes signal loss.

To set the SWR for UHF, we need to adjust the position of the first driving element of UHF after the radiator element.

Testing and Enjoying Your Antenna

After tuning, it’s time to test your antenna. Connect it to your radio and explore the frequencies. You should notice improved reception and transmission capabilities. Experimenting with different locations and orientations can further enhance your results.

Conclusion

Building a 9-element VHF-UHF antenna is an accessible and fulfilling DIY project that can greatly enhance your radio experience. With a bit of patience and attention to detail, you can create a high-performing antenna that meets your communication needs. Happy building, and enjoy the waves!