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| - | ====== Antennas and feed lines ====== | ||
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| - | An antenna couples a radio signal to the space around it. Its behaviour depends on frequency, geometry, installation height and nearby objects. A feed line carries energy between the radio and antenna. | ||
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| - | ===== Common antenna families ===== | ||
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| - | * **Dipole:** a balanced antenna with two conducting sections, often used as a practical starting point for HF. | ||
| - | * **Vertical: | ||
| - | * **Directional antenna:** concentrates radiation in selected directions. A Yagi is a familiar example. | ||
| - | * **Loop:** a closed conducting path, with many possible sizes and designs. | ||
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| - | No antenna is best for every station. Available space, bands, mounting options and the intended paths help determine a suitable design. | ||
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| - | ===== Feed lines and matching ===== | ||
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| - | Coaxial cable is widely used because its shielding and routing are convenient. Balanced lines are another option. Loss, impedance, weather protection and connector quality all affect the complete system. | ||
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| - | **Standing wave ratio (SWR)** describes mismatch along a transmission line. A low SWR is useful, but it does not by itself prove that an antenna radiates efficiently. A dummy load can present a good match while intentionally converting most transmitted energy to heat. | ||
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| - | ===== Documenting an installation ===== | ||
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| - | Include a diagram, dimensions, feed-line type and length, installation height, measurement method and operating conditions. Keep measured results separate from predictions and simulations. | ||
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| - | See [[wiki: | ||