1. The First Idea: Building a 4-Square From Scratch

The project began with a simple but ambitious goal: to understand and build a complete 40 m four-square system entirely from scratch. Instead of purchasing a ready-made coupler, the intention was to learn every aspect of phased vertical arrays — how phase shifts are created, how amplitudes behave, how hybrids work, and how dump power reveals system imbalance.

This early phase was driven by curiosity and the desire to master the underlying physics rather than rely on black-box solutions.

2. Early Experiments With Two Verticals

The first practical step was experimenting with a two-element phased array using the Christman feeding method. These tests included:

• Adjusting coax lengths to create phase differences
• Observing mutual coupling between the two verticals
• Measuring SWR, impedance, and phase behavior
• Watching how small changes affected directionality and dump power

This stage served as a laboratory for understanding how phased systems behave in the real world.

3. First Concepts for a Home-Built Coupler

With the basics understood, the next step was designing a personal coupler. Several approaches were tested:

• Hand-built 90° hybrids
• 180° splitters
• Resistive and ferrite-based hybrid concepts
• Custom switching arrangements
• Early dump-load monitoring

These experiments revealed how sensitive a 4-square is to phase accuracy, amplitude balance, and coax symmetry.

4. Building the First Complete Coupler

A fully self-built coupler was constructed, including:

• Custom hybrids
• Calculated coax transformation lines
• A first-generation controller
• A homemade dump-load system

Field tests included:

• VNA measurements
• S21 and phase measurements
• SWR checks
• On-air directional tests

The system worked, but it also showed how demanding a 4-square truly is. Perfect symmetry and precise phasing are essential.

5. Transition to the RemoteQTH 4SQ-8DIR System

After extensive experimentation, the decision was made to adopt the RemoteQTH 4SQ-8DIR HP coupler. The reasons were:

• Higher reliability for an eight-direction system
• Industrial-grade hybrid networks
• Better long-term stability
• More HF power

However, the installation was not treated as a plug-and-play solution. Every part was measured, verified, and optimized using the knowledge gained from the earlier self-built system.

6. Why This Beginning Matters

The early phase of the project provided:

• A deep understanding of phased-array behavior
• Insight into dump-power interpretation
• The ability to diagnose imbalance and coupling issues
• The skills to tune a 4-square

This foundation is the reason the final system performs as well as it does today.

7. Summary

The ON7MV 40 m 4SQ project did not begin with a commercial coupler. It began with experimentation, learning, and building from the ground up. The transition to the RemoteQTH system was a logical evolution — but the knowledge gained from the early homemade coupler remains the core strength behind the entire installation.