Arduino Antenna Analyzer

This antenna analyzer is a sophisticated, DIY-oriented HF antenna measurement tool, originally conceived by Beric Dunn (K6BEZ) and significantly enhanced by German amateur radio operators DK2JK, DK1BS, and DG7EAO. It is built upon the popular and flexible Arduino Nano platform combined with a Direct Digital Synthesis (DDS) module, offering a cost-effective yet powerful approach to antenna analysis across the 1-30 MHz HF spectrum.

Unlike basic SWR bridges, this analyzer provides a comprehensive sweep function, allowing users to visualize impedance behavior and locate resonant frequencies across a user-defined range.

Core Functionality & Operation
At its heart, the analyzer uses a DDS module ads9850 to generate a precise, swept frequency signal. This signal is fed into the antenna under test. By measuring the forward and reflected power using a directional coupler, the device calculates key parameters such as Voltage Standing Wave Ratio (VSWR/SWR) and, depending on the firmware version, can derive additional impedance characteristics.

The standard version communicates serially with a PC terminal program, where sweep results are displayed as text data (e.g., SWR vs. frequency). However, the modifications detailed on this page by DG7EAO and others expand the user interface dramatically.

Key Features & Extended Capabilities
Versatile Visual Displays:

2.2" TFT Display (DG7EAO Mod): A major enhancement is the integration of a color TFT display for graphical sweeps. This provides a real-time visual curve of the SWR across the selected frequency range, making it intuitive to see the minimum SWR point and bandwidth at a glance. 

Can be interfaced with a 0.96" OLED Display: For a compact, low-power, and standalone solution, an I2C-controlled 128x64 OLED display can be added. This version, using a 4-pin OLED, shows start messages, the selected sweep range, and the final result: the lowest SWR value found along with its exact frequency.

Standalone Operation & User Controls (DJ7OO Mods):

Can be used as a standalone unit - No PC Required: The most advanced modifications on this page enable a fully standalone unit. A physical START button initiates the sweep, and a potentiometer selects one of nine predefined sub-ranges (e.g., 1-30 MHz, 5-8 MHz, 16-20 MHz, etc.). Software to plot on pc is also available. 

Can be interfaced to have a Voice Output (Speech Module): Perhaps the most unique feature is the addition of a speech output module. Upon pressing start, the analyzer verbally announces the sweep's progress. After completion, it speaks the lowest SWR value and its corresponding frequency in clear audio (e.g., "SWR 1.2 at 14.150 Megahertz"). A sound sample is provided on the page.

Rotary encoder is used  to reliably select from the nine HF bands without external controls.

Remote & Wireless Control:

Can Be interfaced with a Bluetooth Adapter (HC-06): The analyzer can be paired with an Android smartphone using a low-cost HC-06 Bluetooth module (operating in slave mode). Using a terminal app on the phone, the user can wirelessly control the analyzer, start sweeps, and view data. The page notes the importance of matching serial baud rates (adjusting the analyzer code from 57600 to 9600 bps to match the module's default).

This project is explicitly for experienced electronics hobbyists and amateur radio operators (hams) who are comfortable with:

Soldering PCBs and sourcing components.

Uploading and modifying Arduino code (C++).

Troubleshooting hardware/software interface issues (pin conflicts, drivers).

Understanding basic RF and antenna theory (SWR, impedance).

Conclusion
This antenna analyzer is not a commercial off-the-shelf product. It is a highly adaptable, open-source-style platform that gives a technically inclined user a professional-grade tool for a fraction of the cost. Through the modifications by DK2JK, DK1BS, DG7EAO, and DJ7OO, it evolves from  a simple serial data logger into a standalone device with TFT graphics, wireless smartphone control, and even audible speech output—making antenna tuning efficient, visual, and even accessible without looking at a screen.
 

Suppied as a kit -PCB only with instructions and download link for the firmware.