page_title: Discone antenna
section_title: Description
hierarchical_section_title: Discone antenna / Description
caption_attribution_description: English: Discone antenna principle. 日本語: ディスコーン・アンテナの原理図。 Disc = 円盤 Circular cone = 円錐 Coaxial cable = 同軸給電線
context_page_description: A discone antenna is a version of a biconical antenna in which one of the cones is replaced by a disc. It is usually mounted vertically, with the disc at the top and the cone beneath.
  Omnidirectional, vertically polarized and with gain similar to a dipole, it is exceptionally wideband, offering a frequency range ratio of up to approximately 10:1. The radiation pattern in the vertical plane is quite narrow, making its sensitivity highest in the direction of the horizon and rather less for signals coming from relatively close by.
context_section_description: The discone antenna has a useful frequency range of at least 10 to 1. When employed as a transmitting antenna, it is often less efficient than an antenna designed for a more limited frequency range. SWR (standing wave ratio) is typically 1.5:1 or less over several octaves of frequency. A discone antenna consists of three main parts: the disc, the cone, and the insulator.
  The disc: The disc should have an overall diameter of 0.7 times a quarter wavelength of the antenna's lowest frequency. The antenna's feed point is at the center of the disc. It is usually fed with 50-ohm coaxial cable, with the center conductor connected to the disc, and the outer conductor to the cone.
  The cone: The length of the cone should be a quarter wavelength of the antenna's lowest operating frequency. The cone angle is generally from 25 to 40 degrees.
  The insulator: The disc and cone must be separated by an insulator, the dimensions of which determine some of the antenna's properties, especially on near its high frequency limit.
caption: Drawing of dimensions
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