Antena Discone

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 exhibiting unity gain, it is exceptionally wideband, offering a frequency range ratio of up to ~10:1. The radiation pattern in the horizontal plane is quite narrow, making its sensitivity highest in the plane parallel to the Earth.

History

On February 6, 1945, Armig G. Kandoian of New York was awarded patent number 2,368,663 [1] (assignor to Federal Telephone and Radio Corporation (later merged with ITT Corporation) for a “broad band antenna”, from an application made on May 15, 1943.

Excerpt from the Kandoian patent:

In keeping with progress made during the last few years in the development of ultra-high frequency radio technique, and applications thereof to aircraft communication, direction finding, and so forth, it has become necessary to develop special antennas and antenna systems suitable for installation on such aircraft. Flying conditions are such that these antennas must necessarily be small and rigid in their construction and also offer a minimum of wind resistance, in order that the flying efficiency of the aircraft will be unimpaired. In accordance with my invention I have provided a small rigid antenna suitable for mounting on the surface of the fuselage or other component of the airplane structure and in certain embodiments I have also provided a streamlined protecting shield or housing covering or so cooperating with the construction of the antenna system as to greatly reduce wind resistance.

Aplications

The discone’s wideband coverage makes it attractive in commercial, military, amateur radio and radio scanner applications.

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 ~2:1 over the range of the design frequency to the second harmonic and ~3.1 thereafter.

The discone’s inherently wideband nature permits it to broadcast undesirable spurious emissions from faulty or improperly filtered transmitters.

Construction Materials

A discone may be made from solid metal sheet (often copper), which is practical for small indoor UHF antennas, such as for Wi-Fi.

At lower frequencies a sufficient number of metal wires or rods in a spoke configuration is often used to approximate a solid surface. This simplifies construction and reduces wind loading.

The spokes may be made of stiff wire, brazing rods or even coat hanger wire.

The optimal number of rods comprising the disc and cone is often quoted as being from 8 to 16.

Components

A discone antenna typically has at least three major components: 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 minimum 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 minimum 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.

Extending Low-Frequency Response

A vertical whip may be placed affixed vertically to the disc in order to extend the low frequency response, but this may reduce efficiency at higher frequencies. In this configuration, at lower frequencies the discone may more closely resemble a ground plane antenna or a coaxial dipole.

Picture:

12 tanggapan pada “Antena Discone”

  1. Antena broadband. Bagus untuk mendengar transmisi lokal. Jelek untuk dx. Bisa transmit di mana saja. Tapi jangan kecewa kagak bisa jauh karena sudut radiasinya tinggi kadang lebih 30 derajat. RF melambung terbuang percuma ke langit.

  2. Weh terimakasih pencerahanya mbah.
    Jadi tambah lagi neh ilmu saya.
    Semula saya menginginkan sekali antena broadband baik VHF yagi / telex atau broadband HF yang bisa 1-30 MHz tanpa tunner itu.

    hank you mbah…

  3. untuk VHF antenna V2R/S telex cukup broadband, kalo mau ebih broadband coba bikin paralel dipole. Untuk HF bikin saja antena OCF Windom Multi band; aku coba bagus di semua Band Amateur, 3,7, 7-7,1, 10,150, 14, 21, 26-29 MHz. No tunerr.

  4. Mbah paijo…
    akhirnya pilihan saya jatuh ke vx 3r (cuma buat nguping aja)
    beli diversakom. Lain kali kalo mau yg lebih tinggi grade-nya dari vx 3r dan budget mencukupi saya msh ttp nunggu taruna dari mbah paijo (lewat tread tentunya). trimakasih mbah…

  5. @Mbah wongso:Thanks pencerahanya mbah…. ne lagi mikir untuk HF. Disini 2 meter sepi, kalau ada HF kan bisa kontak temen2 di jawa.

    @Bro Ismuryanto: Wehhhhh ternyata ambil VX3R juga tho… Selamat–selamat… memang VX3 cocoknya cuma untuk ngiuping aja. Bentuknya kecil ringkas, bisa pakai headphone 3,5mm. Ada frekwensi counter dan frekwensi lebar.
    Sayang power cuma 1,5 watt.
    OK tar kalau ada yang hi-power saya tarunakan di thread…

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  7. oommm??? mohon pencerahannya donk, antena luap apa yang bagus untuk radio HT Icom ic2n??? saya pnya radio warisan orng tua om,, pengen maen2 radio jg,, maklum om saya gk ngerti,,
    mohon pencerahannya ya om?????

  8. oommm??? mohon pencerahannya donk, antena luar apa yang bagus untuk radio HT Icom ic2n??? saya pnya radio warisan orng tua om,, pengen maen2 radio jg,, maklum om saya gk ngerti,,
    mohon pencerahannya ya om?????

  9. @Om wawan…
    HT 2N dikasih antena jenis telex hygain atau RING-O sdh cukup. Kisaran harga 80-100rb.
    Kabel pakai RG58 harga 5rb / meter.
    Kalai mau bagus pakai RG8 harga 11rb / meter.
    Jangan lupa ya antenaya di match bias pesawatnya awet….

  10. di match tu apa ya om artinya?? maklum om saya gk ngerti, saya cuman pake antena yg asli dr HT icom ic2n, tp pengen d tambah antena luar biar jangkauannya luas om,, bisa bantu ajarin gk om gmana sebaikknya??

  11. Di match, disesuaikan dengan frekwensi TX.
    Kalau pasang antena luar (jenisnya banyak), tdk bisa asal pasang trs on air spt pasang antena TV. Kita hrs sesuaikan dengan frekwensi TX nya. Untuk menyesuiakan pakai alat SWR.
    Usahakan mendapatkan nilai VSWR 1:1,0…

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