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hf:antennas

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hf:antennas [2024/08/26 14:45] – m0ltehf:antennas [2024/11/04 18:29] (current) – [Good Resources] ei5iyb
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 +======= Antenna Systems =======
 +
 +====== Antenna Types ======
 +
 ===== The Simple Dipole ===== ===== The Simple Dipole =====
  
-A Simple Dipole can be created from any piece of wire you have lying around. \\  +A simple dipole can be created from any piece of wire you have lying around. 
-A Dipole will normally be a half wave length for the band you are intending to work on. \\ + 
 +A dipole will normally be a half wave length for the band you are intending to work on. 
 + 
 +A dipole has a characteristic impedance of 73 ohms, though hams normally ignore this since it's fairly close to 50 ohms.
  
 Dipoles are band specific. Dipoles are band specific.
 +
 +This is the wiring of a dipole at the end of a piece of coax cable. Notice the red arrow marked C.
 +
 +{{:hf:dipole-feedpoint-without-choke.png?400|}}
 +
 +C is undesirable unbalancing of the dipole due to the fact that the outer skin of the braid of the coax cable is not isolated from the antenna, i.e. B and C are common. To counteract this, a balun is often used. See:
 +
 +  * https://gm3sek.com/wp-content/uploads/2019/01/G3TXQ-RC.pdf
 +  * {{ :hf:gm3sek-private-life-of-coax.pdf |}}
 +
 +This animation shows current and voltage curves on a dipole.
  
 {{:hf:dipole_image.gif}} {{:hf:dipole_image.gif}}
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 https://www.hamradiodx.net/beginner-hf-antennas\\  https://www.hamradiodx.net/beginner-hf-antennas\\ 
-https://www.radio4all.org/how-to-build-a-dipole-antenna/ +https://www.radio4all.org/how-to-build-a-dipole-antenna/\\ 
- +[[https://youtu.be/v9OXRtISCjM|Dud Charman's Aerial Circus]]
 ===== The Vertical ===== ===== The Vertical =====
 The Amateur Radio HF vertical antenna is a type of radio antenna designed for use in the high-frequency (HF) range of the radio spectrum. It typically consists of a vertical radiating element, often a vertical conductor or set of conductors, supported by a mast or other structure. HF vertical antennas are popular among amateur radio operators for transmitting and receiving signals on multiple HF bands. They offer an omnidirectional radiation pattern, making them suitable for general communication, and their vertical orientation helps in minimizing ground losses. Some variations may include additional features such as radials to improve efficiency and performance. The Amateur Radio HF vertical antenna is a type of radio antenna designed for use in the high-frequency (HF) range of the radio spectrum. It typically consists of a vertical radiating element, often a vertical conductor or set of conductors, supported by a mast or other structure. HF vertical antennas are popular among amateur radio operators for transmitting and receiving signals on multiple HF bands. They offer an omnidirectional radiation pattern, making them suitable for general communication, and their vertical orientation helps in minimizing ground losses. Some variations may include additional features such as radials to improve efficiency and performance.
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 {{ :hf:endfed-unun.webp |}} {{ :hf:endfed-unun.webp |}}
  
 +{{ :hf:shortened-efhw-antennas.png |}}
 ==== The End Fed Long Wire / Random Wire ==== ==== The End Fed Long Wire / Random Wire ====
  
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   * https://sparc.asn.au/2022/04/22/random-wire-eflw-antenna-designs/   * https://sparc.asn.au/2022/04/22/random-wire-eflw-antenna-designs/
   * https://www.earchi.org/92011endfedfiles/Endfed6_40.pdf   * https://www.earchi.org/92011endfedfiles/Endfed6_40.pdf
 +  * {{ :hf:wire_lengths_for_4_and_9-1_ununs-3.pdf |}}
 +  * {{ :hf:wire_lengths_for_4_and_9-1_ununs_table.pdf |}}
  
 Both the EFHW and EFLW can be deployed in creative ways, e.g. slopers, wound around poles, inverted L, fully horizontal, but might need some adjustment to compensate for that (and the surroundings). Both the EFHW and EFLW can be deployed in creative ways, e.g. slopers, wound around poles, inverted L, fully horizontal, but might need some adjustment to compensate for that (and the surroundings).
 +
 +====== Matching circuitry ======
 +
 +[[https://www.onallbands.com/types-of-feed-line-chokes/|Types of feed line chokes]]
hf/antennas.1724683512.txt.gz · Last modified: 2024/08/26 14:45 by m0lte