The determination of the focal position needs to be calculated based on the shape of the selected parabolic surface. 
Calculation formula: F=D × D/16H (m)
Among them, D is the diameter of the parabolic surface, H is the depth of the parabolic surface, in meters.
Considering the existence of certain errors, a simpler estimation formula can be used for calculation, namely F=0.3D to 0.4D. ”
(Calculation formula: F=D × D/16H (m))
Among them, D is the diameter of the parabolic surface, H is the depth of the parabolic surface, in meters.
Considering the existence of certain errors, a simpler estimation formula can be used for calculation, namely F=0.3D to 0.4D. )
F is the focal point of the concave convex mirror The antenna is placed at the focal point, and the signal is concentrated on the antenna through the reflection of the mirror You can determine F based on the second estimation formula. As for the depth, you can adjust it slightly according to the strength of the signal
Correspondence between 2.4G channels and frequency points:
Channel frequency point (MHz)
1 2412
2 2417
3 2422
4 2427
5 2432
6 2437
7 2442
8 2447
9 2452
10 2457
11 2462
12 2467
13 2472
14 2484
Keywords: parabolic surface, focal point
A more common explanation for the working principle of a gain antenna is to place a regular metal parabolic surface around an existing antenna, so that the antenna is located at the internal reflection focal point of the parabolic surface. Energy concentration is formed at the focal point through electromagnetic wave reflection, thereby enhancing the transmission and reception of electromagnetic signals and achieving signal enhancement in a specific direction.
The key to making a simple gain antenna is to find a relatively regular metal parabolic surface and calculate the focal position of the parabolic surface. Metal paraboloids do not necessarily require the use of metal plates, but can also be made of mesh or fence like metal materials. The determination of the focal position needs to be calculated based on the shape of the selected parabolic surface.
Calculation formula: F=D × D/16H (m)
Among them, D is the diameter of the parabolic surface, H is the depth of the parabolic surface, in meters.
Considering the existence of certain errors, a simpler estimation formula can be used for calculation, namely F=0.3D to 0.4D.
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China Wireless Network Forum
The calculated values of the diameter, oscillator, and length of the cylindrical antenna can be directly entered and calculated on the following webpage, website: http://www.saunalahti.fi/elepal/antenna2calc.php
Related WIFI antenna production website:
http://hi.baidu.com/ichi/blog/item/361ccaea1674d9d3d439c900.html
http://www.binarywolf.com/249/
http://www.qsl.net/ve3rgw/corner.html
http://www.turnpoint.net/wireless/cantennahowto.html
http://trevormarshall.com/biquad.htm
http://www.xaviervl.com/Antenne/Bi-quad/index.html
http://www.usbwifi.orcon.net.nz/
Several websites for making 2.4GHz antennas
http://www.saunalahti.fi/elepal/antennie.html 
http://www.frars.org.uk/cgi-bin/render.pl?pageid=1058 
http://martybugs.net/wireless/biquad/ 
http://trevormarshall.com/waveguides.htm 
http://www.guerrilla.net/gnet_2_4ghz.html 
http://seattlewireless.net/index.cgi/CardboardHorn
http://www.dlinkbbs.com/forum-74-1.html To register, it's pretty good
http://www.meshmea.net/articles/wlan/index.html
http://www.meshmea.net/articles/wlan/antenna/diy/index.html
Finished product purchase at: http://www.rf-net.net/new_page_5.htm
http://www.hellocq.net/forum/showthread.php?t=102999&page=1&pp=30
http://www.hafs.cn/bbsxp/ShowForum.asp?forumid=22
http://www.saunalahti.fi/elepal/antenna2calc.php Calculating parameters
Here is a large amount of information on 2.4G amplifiers:
http://www.qsl.net/n9zia/wireless/appendixD.html
Practical Antenna Design and Manufacturing http://www.vr2xuk.com/ham/ant060711.rar
http://howin.net/ Practical Antenna Design and Manufacturing. Rar 100MB