Homebrew 2.4 GHz 14 dBi Wide Angle Sector antenna |
By Dan Santillan |
 I’ve been wanting to have a sectored antenna, but due to strict policy of importing high-gain antenna in this country, it is very difficult to find a directional high-gain antenna, however; if there is one available it cost a lot, in the US a typical sector antenna cost around 100-200 U.S. Dollar (depending on brand and model) but in this country any antenna can cost more, almost 5 times the price in the U.S. a good example of antenna price here is the d-link 8dbi patch antenna, we all know that this antenna cost under 50 dollars, but here, the same brand and model cost at least 210 dollars (what a rip off!), anyway, I was so desperate to have a sectored antenna, I already build a biquad, double-quad, cantenna etc… I have not missed to build any homebrew antenna I could find on the internet, I’ve done some of my antenna home brewing using a machinery and you could say it is almost a commercial grade, however those antenna I already build doesn’t provide me the beam width I needed, most of the homebrew antenna on the net provides from 5 degrees to a maximum of 80 degrees on horizontal. |
 I’ve been digging the net for a homebrew sector antenna for nearly 8 months and still no luck, until… I found an article in PDF format about the “Planar Omni Directional” written by group of people, the theory of the common omni designs has been explained namely the “Franklin Array (omni with u-shape for the phase , Meanderline Phase (omni with a coil for the phase, similar to aerialix), and the COCO design (an omni with an alternate element soldered together ,similar to grump design) I’ve read the whole article but nothing was mentioned about the sectored antenna and because of my desperation to have a sector antenna I started to experiment different design using the EZNEC antenna modelling program. |
 My initial approach was to design a “Franklin Array” omni antenna because I’ve done the Meanderline with a reflector before and it’s a no performer, I did not try the COCO yet as soldering the joint is difficult, basically this antenna is a centre fed dipole with a “U” shape for shift phasing instead of a coil, so far so good, the design seems to be good but the result was not very promising, the theoretical gain I can get is within 2-3 dBi only!, (aerialix design performs much better than this!) I was not happy with the result so I revised my design again, this time I put a 123mmX123mm reflector at the feed point with a distance of L1/2 from the feed , to my surprise the gain jumped from 2-3dbi to 3-4 dBi! well that is interesting! an increase of 1db (obviously because of the reflector), the sphere also changed from a typical omni pattern to a directional pattern with 30 degrees of beam width horizontally and about 10 degrees vertically, I modify the reflector with different dimension from 1wavelength down to 1/4, after making lots of adjustment which are all based on wavelength, the only size that seems to show a good result is by using the L 1/2 x 1 size, there was no difference with the gain, however the beam width improved a lot! from 30 degrees to almost 118 degrees! my modelling seems to give me a good result, I continue adding more reflector until I reached the top and bottom of the element with an extra 1/4L from the tip of the element, to my surprise the gain increased from 4dbi to 11.5dbi! the beam width stays the same. I’ve check the svwr and it is within the acceptable figure which is 1.2 - 1.5, the design seems to be ideal for a sectored antenna, it is now time to put everything in practice!. I will post all relevant result from the modelling program later on, meanwhile; I will start to make the “sectored antenna”. |
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November 28th, 2005 at 14:34
Wow! very impressive.
I’ve build several antenna for wifi but have never found a design for a sector before.
I look forward to you long distance results.
Dan
November 29th, 2005 at 17:59
Got the idea, I am building a sector antenna based on your design, but will be using a different radiating element.
January 14th, 2006 at 16:42
I too live in Saudi Arabia, Rabigh is home for me, Facing the same problem, need 150 metes of WIFI coverage. Any help or joined support, would be great.
Regards
Lamar
April 12th, 2006 at 23:42
What is the dimension of center element copper wire.
May 9th, 2006 at 16:31
What are the dimensions of center element.
May 23rd, 2006 at 13:25
Great job guys… Thank for you work…
June 11th, 2006 at 17:35
Perhaps you should put a link to the original design ?
http://www.qsl.net/yu1aw/vhf_ant.htm
June 15th, 2006 at 1:03
@foobar
what makes you think that the link you provided is the original design? are you aware that the 4NEC2 has a template for that particular design? are you also aware that i have the pdf documents the chap did mentioned? he clearly states how he did his and none of your so called “orginal design” has the same dimemsion he used, although it has the same design look. That doesn’t mean he copied it or got the idea from your so called “original” design.
incase you are not familiar with the things i mentioned, STFU.!
give the chap some credit.
June 25th, 2006 at 6:26
Great.
Can we increase the gain by increasing the number of elements.
July 17th, 2006 at 20:53
My first project was a radio telescope 10 years ago, now I would like to build something that is
VERY directional and can send and recieve to and from wifi devices with a range of over 2km
what type of antenna is required I would rather build the thing myself if possible
Please help
August 14th, 2006 at 16:29
Did yoy see amos 9 sector antenna? http://www.qsl.net/yu1aw/vhf_ant.htm Ithink it is a good antenna, i have made one and it works better than pacific wireless SA24-90-17 antenna, and i did not make it with perfect reflector. If some one try to make one i have interesting solutions for easyer making, contact me one zoran.s@verat.net.
August 19th, 2006 at 12:15
I am going to build it soon and let gives u the result