Instructables
Picture of Bi-Quad WiFi Antenna
All WiFi users are constantly wanting more powerful signals. In this instructable we demonstrate how to build a simple but power double bi-quad WiFi antenna.

Parts List

A single-sided copper clad PCB sheet - I found a 20x10cm sheet with an incomplete circuit printed on it but not etched. The print was cleaned off with wire wool.

A length of 1mm diameter bare copper wire - I found a length of mains cable and removed the earth wire.

An N-type chassis connector and an N-type to SMA adaptor.

Four nuts and bolts for attaching the N-type chassis connector to the PCB.

Drill, soldering iron, solder, pliers and your favoured nut and bolt tightening tools

Your WiFi adaptor. I use an Alfa awus036h.

For my other projects see - http://www.ecopunk.org.uk/p/projects.html
 
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Step 1: The Antenna

Picture of The Antenna
Here we see a close-up of the antenna. A hole has been drilled into the PCB to accept the N-type chassis connector. Note the sheet of plastic. My initial thought was to shied the plate from the antenna but subsequent experiments have shown no change in signal strength so you do not need this plastic shielding.

You can also see the antenna constructed from the 1mm earth wire. You need to bend the wire so that it forms the diamond pattern as in the photo. Each side of the diamonds are 30.5mm. At the crossovers the wire does not touch itself.

One end of the antenna is soldered to the N-type at a height of 15mm from the collector plate. The other end is attached to one of the bolts holding the N-type chassis connector in place.

Step 2: Rear of Collector Plate

Picture of Rear of Collector Plate
Here we see the rear of the collector plate, with the N-type bolted in place. Here is where we screw on the N-type to SMA adaptor.

Step 3: N-type to SMA adaptor

Picture of N-type to SMA adaptor
This is the N-type to SMA adaptor. Most WiFi stick antennas use SMA connectors so you will need to make your bi-quad compatible.
How much range will it give?
WIll it work with BSNL wimax??
About how much range did you get with this antenna? I'm about to buy the parts to do this.
TheGoodLife (author)  redstonenico2 years ago
It all depends on your skills as a constructor, on if you use something like a dish to concentrate the incoming signal and on if you can shield noise out of the signal as much as possible.

I have since moved on to a Yagi, for which, I will produce an instructable in the future.
I've been looking at more of these Bi-quad antennas and they seem to be connected to a cable dish, do they need to be connected to one to be able to receive signal or is that just for better signal?
TheGoodLife (author)  redstonenico2 years ago
The dish is for increased signal. You will get an improvement with a standalone bi-quad over the omnidirectional stick antenna.
wiFreedom3 years ago
HERE is the write up on a 125 mile linkup between Nevada and Utah.  The 125 mile was not amped, but the 143 mile was.
TheGoodLife (author)  wiFreedom3 years ago
An interesting read. Anything is possible with the right tools and research.

Thanks for posting to this Instructable as it has made me want to improve my hardware.

I have retired my Bi-Quad and started to build a Yagi.

yskroc3 years ago
Will it yield better result if I use a bigger reflector??
Thanks.
TheGoodLife (author)  yskroc3 years ago
I don't think you would get much payback for a reflector that much bigger than the bi-quad element.

You can build bigger collectors with many elements on them and then link the elements together. You will need to do a search for larger bi-quads.
wiFreedom3 years ago
http://www.youtube.com/watch?v=rBBKSk627BM&feature=related It appears a lengthy range can be acheived.

http://www.youtube.com/watch?v=rBBKSk627BM&feature=related
wiFreedom3 years ago
I am in the process of building a single biquad out of a dish 500. I plan to mount the Alfa inside of the dish and USB out it's lower end into the laptop. It stands on a modified tripod guitar stand. It will of course be modified from the instructions (linked)
http://www.engadget.com/2005/11/15/how-to-build-a-wifi-biquad-dish-antenna/
A personality on another forum told me that he has achieved 175 miles with his biquad in ideal conditions. Though I expect that to be an overstatement, I still will be expecting to see most of the APs in my small city of 100k people so it should be pretty noisy..
I am also researching converting everything (including my Alfa) over to type F connections for universality. I understand that 50 ohm is the RF standard so I figure 50 OHM connectors and a very short length of 400 series coax cable will do the trick.
I will report my findings in a few weeks.
Peace
TheGoodLife (author)  wiFreedom3 years ago
I'd very much like to read your findings so make sure you post a link.

I think all the long distance connections are set up rather than random finds. In other words the claimer is optimising both ends; maybe a high-power AP (possibly with a dish at that end too) and then searching only for that AP.

I can get about 40 APs, in my street alone, with my current setup. The number of open and WEP APs is very small. Time to cast the net wider.
The minimum range I will accept is roughly about 1500 yards, but of course I'd like a few miles of range.

Your suggestion makes perfect sense regarding both ends being dish equipped. I'd bet that the AP had a unidirectional amplified feed as well, and possibly from a higher elevation to a lower on a fair weathered day.
can i use this antenna for the hspa dongle
TheGoodLife (author)  prabath19889143 years ago
I would say that HSPA and WiFi use different frequencies, therefore have different wave lengths.

The dimensions of the bi-quad antenna are matched to the wave length of WiFi and would not work with HSPA.

You would have to make an element of different dimensions.

If you Google "hspa bi-quad" you will find information. Much of it vague and not in English.

Read the literature on WiFi biquad. Determine why the dimensions are what they are for WiFi and scale to HSPA wave-lengths.
celalboz3 years ago
N male to RP-SMA male needed to connect the alfa's male connector to N chases connector, correct?
before I buy N male to RP-SMA male ...
TheGoodLife (author)  celalboz3 years ago
Yes, that is correct.
Your approach is very professional and I thank you for your attention to detail.
I will be building a parabola by using a giant umbrella and I was hoping to use this as an nlb to it, how small can I get when I build a bi-quad you think? 5cm x 5cm?
thanks

TheGoodLife (author)  celalboz3 years ago
Firstly, I am not sure if an umbrella will work as it has no reflective qualities. An old satellite dish would be the thing to use. Unless you can coat the umbrella with foil or something that will reflect microwave radiation.

As far as the bi-quad is concerned, the bigger the better. Also the more elements the better. I have seen much bigger with many more elements.
acosmica3 years ago
this will be my new project
thank you !!! really good job :)
TheGoodLife (author)  acosmica3 years ago
Glad you liked it.

I use it on my DD-WRT repeater and in my car whilst War Driving.
rkr TheGoodLife3 years ago
What's the farthest distance you've been able to connect to it?
TheGoodLife (author)  rkr3 years ago
I haven't deliberately gone out to see what the range is but so far I have connected to a router 200 meters away whilst war driving in a village.
cool. my grandma do have old dish so i can bring it :) and i will buy a biquad on ebay.
i want to know your biquad connect miles up to ????
TheGoodLife (author)  supremedragonx3 years ago
I struggling am you to understand.

Use the bi-quad as an LNB on a satellite dish and you will probably get many miles for your bucks.
Do you get better signal from doing the double-biquad?
TheGoodLife (author)  MechanicalApe3 years ago
I've never built a single bi-quad but all my searches on the net suggested an improvement.

The laptop I'm using now is connected by WiFi to a dd-wrt router acting as a repeater, which itself is connected by WiFi to a router about 60 meters away.

The repeater router has my bi-quad in place of one of the stick antennas. Works perfectly. The repeater router would not pick up the main router with just stick antennas.
Dr. Pepper3 years ago
Very nice!
TheGoodLife (author)  Dr. Pepper3 years ago
Glad you like it!
Yeah, it's cool!