If you’re a ham radio operator working with limited space, building an indoor antenna for 7 MHz can be a game-changer. Whether you’re in an apartment, a shared living space, or simply want a stealthy setup, this compact antenna design from F6CYV offers an effective solution without compromising performance.
Indoor Antenna – Materials and Dimensions
This indoor antenna is specifically designed for the 7 MHz band (40 meters) and can be built using readily available materials:
- Horizontal sections: Two arms, each 1.60 meters long
- Vertical sections: 0.50 meters on each side
- Coils: Two inductors made with 20 turns of 1mm wire on 3-inch PVC pipe
- Feedline: 75-ohm coaxial cable
The coils are positioned between the horizontal and vertical sections, spaced 0.80 meters from the center feed point. This configuration helps achieve resonance at 7 MHz while keeping the antenna compact and suitable for indoor use.
While indoor antennas may not match the efficiency of full-sized outdoor dipoles, this design delivers surprisingly good results for local and regional contacts. With proper tuning and placement, you can expect solid performance on the 40-meter band, especially during evening propagation windows.
Indoor Antenna – Assembly Tips
- Use quality PVC for coil formers to ensure stability.
- Keep wire turns evenly spaced to maintain inductance.
- Mount the antenna horizontally near the ceiling or vertically along a wall for best results.
- Use an antenna analyzer to fine-tune resonance around 7 MHz.
While indoor antennas may not match the efficiency of full-sized outdoor dipoles, this design delivers surprisingly good results for local and regional contacts.
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