Helical Antenna Design Software
Internal view of helical monopole antenna
HelixCalc is a program for deriving a template for helical windings
on former (usually a tube) to make a helical antenna.
The premise is that you have a particular tube diameter and frequency
and you can alter various parameters such as length in order to get the desired gain.
The formulae, theory and contraints are taken from the ARRL Handbook,
chapter 9, page 23. The theory goes thus:
Clambda = 0.75 to 1.33 wavelength circumference of winding
Clambda = pi * D * wavelength circumference is also PI times the diameter (D)
Slambda = 0.2126 to 0.2867 Clambda axial length of one turn
G = 0.8 to 1.1 wavelength diameter of ground plane / reflector
Gain = 11.8 + 10*log10(Clambda * Clambda * n * Slambda) where n is the number of turns.
3dB beamwidth = 52?/ (Clambda * sqrt(n * Slambda)) half power beamwidth in degrees
Details on using this program to construct a helical antenna,
particularly for 2.4GHz wireless LAN use can be found at: http://www.air.net.au
Set the centre frequency in MHz (ie 2.425 GHz is 2425
MHz) and the outer diameter of the tubing you will use as
the helix former. Toggle the Units radiobutton to change
the length and diamater values between centimetres and
Adjust the length and number of turns until you get a gain
setting you are satisfied with. The larger the Slambda
scalar is, the higher the gain will be.
Select which orientation you want the spiral to be, left or
right handed. Remember that this oriention must be
preserved for two helicals pointing to each other.
When you are satisfied with you values, select to print. If
the templates won't fit on the printer page, they won't print
out at all; use a larger page such as A3. 2.4GHz and
frequencies will fit on A4 just fine. You should get a
winding template and a circle template for the backplane.
This program is designed to keep any values entered
within certain constraints so you don't end up with a
For a helical dipole of length 2 h, reference : Rr = (1280 x h^2)/λ ^2
For a helical monopole of length h the impedance will be half the helical dipole impedance :
Rr = (640 x h^2)/λ ^2
The equivalent circular radius r0 of a rectangular conductor is r0 =0.35t + 0.24w
where t is metal thickness, w is the conductor width.
The free space wavelength can be found using: λ = c0 /Freq
where c0 is the speed of light in vacuum (3x10^8 m/s). Expressing the frequency in MHz,
the wavelength in meters can be found by: λ [m] =300 /f[MHz]
다음은 헤리컬 안테나의 계산공식이 있는 사이트입니다.
빈칸에 필요한 숫자를 넣으면 결과가 나옵니다.
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