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About This Tool
Small transmitting magnetic loop antennas (circumference under 0.25 wavelengths) exhibit very low radiation resistance, meaning total efficiency is dominated by conductor skin effect, tuning capacitor equivalent series resistance (ESR), and ground proximity losses. In this compact antenna sizing workspace, loop characteristics are represented by three inputs: a radiating loop conductor dimensional factor ($V_1$), an operating frequency radiation multiplier ($V_2$), and an ohmic loss resistance divisor ($V_3$).
The utility evaluates the primary radiation emission metric ($[V_1 imes V_2] / max(0.01, V_3)$), the root RF current distribution factor ($sqrt{max(0, V_1 imes V_2)}$), and the relative loop radiation efficiency share ($[V_1 / (V_1 + V_2)] imes 100$).
### Distinct Worked Calculation Evaluating a 20-meter amateur radio magnetic loop built with copper tubing: - Conductor Dimensional Factor ($V_1$): 128 - Radiation Multiplier ($V_2$): 36 - Ohmic Loss Divisor ($V_3$): 8
Step-by-step results: - Primary Radiation Metric: $(128 imes 36) / 8 = 16 imes 36 = 576.00$ - Current Distribution Root: $sqrt{128 imes 36} = sqrt{4608} approx 67.88$ - Radiation Efficiency Share: $[128 / (128 + 36)] imes 100 = (128 / 164) imes 100 approx 78.05%$
### Client-Side RF Antenna Sizing Guarantee All antenna formulas execute 100% inside your web browser. Loop dimensions, transmitter power levels, and operating frequencies are never sent over the internet.
How to Use
- 1
Enter the radiating conductor dimensional factor into the primary input box.
- 2
Specify the operating frequency radiation multiplier in the second field.
- 3
Input the ohmic conductor loss divisor into the third numeric box.
- 4
Inspect the computed primary radiation metric, current distribution root, and efficiency percentage.
Frequently Asked Questions
Why does conductor tubing diameter matter in magnetic loops?
Because circulating RF tank currents can reach tens of amperes, large-diameter copper tubing minimizes skin effect resistance to maximize radiation efficiency.
What voltage can develop across the tuning capacitor?
Due to exceptionally high tank Q, even modest 100-watt transmitter inputs can generate several thousand volts across the variable tuning capacitor plates.
Are your amateur radio dimensions uploaded to any database?
No. Antenna radiation efficiency numbers never leave your personal computer.