IntroductionThis is basic instructions for handmade WiFi 5-5.8 GHz 13-14dBi Double BiQuad external antenna.
Note: The dBi scale is logarithmic in base 10, where +3 dBi is a doubling in gain! An increase in gain of +1 dBi is equivalent to an increase of 26% and +2 dBi is equivalent to an increase of 60%. This means that the increase in +1dBi is a big deal.
I used computer software 4nec2 (antenna modeler and optimizer) version 5.8.11 to model theoretically the perfect antenna. All measurements based on very careful analysis with computer software which results many times has been proven to be quite accurate and reliable in physical world.
5 - 5.8 GHz is fairly wide frequency range so I calculated 6 antennas for 6 diff. frequencies: 5200, 5300, 5500, 5580, 5700, 5805 MHz and found out that all parameters is quite the same, so instead of dozen antennas for every channel I would recommend single based on average calculations from six simulations. Hence here's a guide.
|(Simulation parameters for six antennas and averages)|
Target frequency 5200 - 5805 MHz
Simulation NEC Input files:
Configuration symbols in NEC Input files:
- ED - Element square diagonal length / 2
- WR - Wire radius
- S - Spacing between element and reflector
- RH - Reflector height / 2
- RL - Reflector length / 2
- LH - Height of reflector "lips"
All dimensions in .NEC data files and graphs are in wave-length ratio.
Main 4nec2 windows with parameters (antenna with lips on the left, without on the right)
Gain (antenna with lips on the left, without on the right)
3D Radiation pattern
Building the antennaI will not show you picture after the picture how to drill the hole in center of reflector. How to use ruler. How to do proper soldering. What kits to use and etc. There are plenty of tutorials for these steps: http://www.ziva-vatra.com/index.php?aid=16&id=SGFyZHdhcmU=, http://martybugs.net/wireless/biquad/ or http://martybugs.net/wireless/biquad/double.cgi
(Note: all calculations in links are for 2.4 GHz WiFi antenna. Use mine calculated data and measurements for 5-5.8 GHz antenna.)
(Note: Pictures below not to scale)
Use this PDF file for bending wire contour. Print without changing scale and contour will be correct size on paper.
Before you start to bend the wire, make it straight as you can.
|Mine wire bending technique in the crossing sections.|
Note: You must leave a ~1.5 mm gap between the element wires cross overs and solders.
Guidance and recommendations
|N-connector in the center of reflector. Maintain correct reflector’s dimensions.|
|Maintain correct spacing between the element and the reflector! 0.5 cm (or 0.4 cm if yours without lips)|
|Finished. Lying on the belly.|
|This antenna should get the best performance at horizontal polarization. |
Note: The antenna is horizontally polarized then reflector is held vertically.
If you intend to use this antenna outdoor, you will need to make it weather-proof to prevent corrosion.
Some people have used small tupperware containers, but it looks ugly at the top of the roof. I rather choose the corrosion… Or the good painting with some silicone on soldered contacts.
After you build your own antenna, you need proper cable with connectors to connect antenna with your modem.
Click here: Guide to Antenna Cables & Connectors
References3.5 GHz antenna 4nec2 analysis and testing: http://wimaxvedlys.blogspot.com/2013/02/double-biquad-35-ghz-wimax-antenna.html
MIMO technology tests, two antennas gives better performance (Use two only if you have weak signal with one): http://www.danlampie.com/?p=708
How-To: Build a WiFi biquad dish antenna: http://www.engadget.com/2005/11/15/how-to-build-a-wifi-biquad-dish-antenna
Last updated on 11 Jul 2014