- Hacer Antenna Wifi Biquad Antenna For Sale
- Hacer Antenna Wifi Biquad Antenna Review
- Biquad Antenna Design
- Hacer Antenna Wifi Biquad Antenna System
One of my latest obsessions is building DIY homebrew WiFi antennas.
Jul 27, 2015 - Easy to Build WIFI 2.4GHz Yagi Antenna: This antenna will extend the range of your WiFi or 2.4GHz devices (like surveillance cameras) into many miles and kilometers. A yagi antenna is basically a telescope for radio waves. I tired the pringle can antenna and the Yagi beats it hands down. Biquad antenna can be built with materials found in most hardware stores. It offers good directivity due to the metallic reflector used in the design. The radiating element are two square with the side length equal to 1/4 midband wavelength, 32mm for 2.440GHz in our case.
- The dual bi-quad antenna, also known as the 'bow-tie' antenna is a directional antenna ideal for use with mobile phones for UMTS, G2, G3, G4 and WiFi equipment. It can be constructed from any common household copper wire 2-2.5mm. The reflective surface can be any conductive material, I have heard that even CD's work as effective reflectors.
- For information on connecting a biquad antenna to a wireless radio, have a look at the page on using wireless antennas. When using a biquad to establish a link to another wireless device, you should ensure the polarisation of the biquad is the same as the antenna you are connecting to. Similarily, if establishing a link with two biquads, ensure.
Heinz Beans Cantenna
This is the first antenna I built. It's the ubiquitous circular waveguide'cantenna':I obtained my can by going to my local 99 Cents Only store and buying a can ofHeinz beans, which happened to be desired 3.25' diameter. The resultant methanegas produced from consuming the beans was used to power my soldering ironafterwards.
I will not go into the construction details, as they are very well documentedon Greg Rehm'ssite. Finding his online cantenna calculator rather intriguing, I set out tofind the mathematical roots to his calculations. The result is my own cantennacalculator program, which I wrote in in C++, based on formulae obtained fromthe ARRL Antenna Book. It's available on my freesoftware page; the archive contains both a Win32 console-mode EXE and fullsource code. In addition, Adam Lesser has kindly supplied a binary forOS-X.
Greg Rehm's calculator fixes the operating frequency at Channel 6 (2437MHz),which is the center channel in the USA, giving the best tradeoff if you want tobuild a general purpose antenna which works across Channels 1-11. On the otherhand, my calculator lets you tune your antenna for maximum gain on a specificchannel; this is handy if you want to use your antenna set up a permanent pointto point link. Let's go through an example using my calculator. The syntax ofthe program is
cantenna diameter centerchannel
where diameter is in mm. So to make an antenna optimized for Channel 6 using my3.25' (82.55mm) diameter can, we would invoke it as follows:
D:>cantenna 82.55 6
Lincomatic Circular Waveguide Calculator V1.1 (Feb 25 2004 23:03:31)
Waveguide diameter: 82.550000 mm (3.250000 in)
Channel: 6 (2437 MHz)
TE11 Cutoff (MHz): 2128.387692
TM01 Cutoff (MHz): 2779.953846
Guide Wavelength (mm): 252.566154 (9.943549 in)
Operating wavelength (mm): 123.017012 (4.843189 in)
1/4 Guide Wavelength (probe to back) (mm): 63.141539 (2.485887 in)
Probe Length (mm): 30.754253 (1.210797 in)
probe pos (Ch1): 66.046774
probe pos (Ch11): 60.564048
probe pos (Ch14): 58.520674
difference between Ch1-Ch11 (mm): 5.482725
So what's the meaning of all this gibberish? The probe should be 30.8mm(1.21') long, and should be set 63mm (2.5') from the inside of theback lid of the can. The operating wavelength of 4.8' shows us thatwe don't have to worry that the sides of the can have ridges, because the theirdepth is insignificant compared to the wavelength our signal. The GuideWavelength is the wavelength of our waveguide. The TE11/TM01 Cutoff frequenciesgive us the approximate upper/lower frequencies of operation for our antenna.Since Channel 1 is centered at 2412MHz and Channel 11 is centered at 2462 MHz,we have a comfortable margin. Now the interesting part is that if you wanted totune the waveguide for the center frequency of Channel 1, you would use a probedistance of 66.04mm instead, and for Channel 11, you would use 58.52mm. Whatthis means is that there is a whopping 5.48mm difference in the optimal probedistance between Channels 1 and 11, so if you are going to use the antenna on afixed channel, it's better to enter than channel number instead when running theprogram.
Experimenting with my calculator program, I've found some interestinginformation. As the waveguide diameter increases, the difference in optimalposition for the driven element between Channels 1-11 drops. I triedupping the diameter iteratively until the TM01 cutoff frequency started to gotoo low to do Channel 11. From my studies, it seems that about 92mm is theoptimal diameter for the waveguide if you want to try to optimize it forflattest response across Channels 1-11; this is because it minimizes thedifference in the probe position between Channels 1-11 -> about 2.63mm, sothe SWR curve across the WiFi band is flatter.
Contrary to popular belief on the Internet, a can length of 3/4 the waveguidewavelength is not optimal. The ARRL Antenna bookrecommends 2-3 waveguide wavelengths instead. I've found that adding more cansindeed increases the gain. A 4-can one is the longest I tried; I didn't writedown the gain testing results, but it was considerably better than the 1-canantenna. Adding more cans helps launch the standing waves in the can better. bmoore314has some excellent info in this Netstumbler.comthread, including info about adding a conical collector to it. Myresults from experimenting with a conical collector are documented in thesection about my Bazooka Cantenna.
Toothpick Monopole
This is my first attempt at designing something myself. I downloaded the EZNECdemo from www.eznec.com and started fiddlingwith it. I still don't have a good grasp of how to model a real ground plane,but i was able to get some plots and start tweaking things.
I started w/ a quarter wave whip. In the US, Channel 6 is the middle channel at2.437GHz. This makes a quarter wavelength about 30.6mm, so I started with thisand just experimented w/ various lengths to change the pattern and SWR and endedup with 89mm. EZNEC shows SWR of 1.2-1.6 over the WiFi band and gain of 4.35dBmax assuming a perfect ground (which we don't have). Below are plots of my EZNECmodel:Here is my prototype:
It's just a piece of 2mm dia. coat hanger cut to 87mm and soldered into anN-female panel jack for 89mm length from the tip to the base of the middle pinon the jack. Just for the hell of it I soldered on the ground plane, which isthe lid of a 3.25' dia. tin can. The tape is just to keep me from shreddingmy fingers on the sharp edges. How well does it work? I was amazed. walkingoutside with MiniStumbler, i can find my AP 120ft farther away than with theORiNOCO built in antenna. Inside the house, I went the the place w/ the worstreception and the signal & SNR went up by over 10dB vs the built in antenna.I haven't even begun to tweak the thing yet. not bad for a $4 antenna (the costof the N jack).
Comtelco 7.5dBi Patch Antenna Clone
This antenna has a pageof its own.Mobile Mark 5dBi Ommi Clone
The Mobile Mark 5dBiantenna is the stumbling antenna of choice used by many Netstumblers. outcast_onewas kind enough to post some pictures on the Netstumber.com website which wereclear enough to get measurements from. Hope he doesn't mind my re-posting themhere:From the above photos, I estimated the dimensions below:
- wire: ~1.5mm OD
- ground plane to coils: 34mm (9.5mm of that is under the black plastic bump..wonder what's in there?)
- length of coils: 13mm
- coil ID: 5mm
- coil OD: 7mm
- coil spacing: ~3-3.5mm
- coils to top: 51.5mm+13mm(plastic tip)..wonder how high the wire goes into the tip.
I used solid copper wire cut out of a piece of Romex...I forget the gauge..itwas all I had available; tried initially to bend a coat hanger but the steelwire was too difficult to bend into the coils. Once again I used a 3.25'can lid as the ground plane; this is close enough to Mobile Mark's specified3' ground plane. A nicer implementation would be to use a discarded harddisk platter (kudos to sparafina for that idea). I am worried that thecopper is too soft to stand up to high winds when attached to my car. When I geta chance I will either encase the whole whip on a plastic tube or just supportthe coil by inserting a suitable piece of plastic into it. Another idea is tojust fill the coil with hot glue.
My initial tests were not that promising...the gain was about the same as mytoothpick, except that the antenna seemed less sensitive to polarization.However, stumbling with the antenna has shown that on the average, I pick upAP's 1-2 car lengths farther away than with the toothpick, and the SNR is oftena little higher. Therefore, this antenna is used in my current stumbling rig.
Hacer Antenna Wifi Biquad Antenna For Sale
Trevor Marshall's BiQuad
Trevor Marshall has posted plans, as well as NEC2 models for his biquaddish feed. The antenna can also be used standalone.I fashioned the reflector from a discarded tin can. The reflector is 123x123mm,with 30mm 'lips' as specified by Trevor for standalone use. The drivenelement is composed of copper wire I got out of a piece of Romex, with 30.5mmlegs, and is suspended 15mm above the reflector. The antenna as pictured above wasa complete failure and had horrible performance. Trevor explained tome via e-mail that I messed up the feed (the photos on Trevor's site aregrainy). Here is my revised feed:
Instead of rigid coax as specified by Trevor, I just used some more copper wirefor the connections; I'm not sure how this affects VSWR, but the antenna gave meabout 3dB more gain than my Comtelco patch clone during my initial tests.
Bazooka Cantenna
I've been trying to hook up my brother, who is a professor at a local college tohis campus network. He lives just on the edge of campus, and although the ITDept. has discussed putting an AP on his side of the street, no progress hasbeen made for several months. Therefore, I decided to take matters into my ownhands. There are tons of AP's just around the corner and out of LOS from mybro's house, but his block is strangely completely devoid of any signal.Finally, one day I climbed up on his roof to see if I could get LOS and a signalfrom a yagi on a hill which was pointed away from my brother's house. I used myORiNOCO card in my Jornada, pointed my biquad through a tree, and amazingly gota 5dB SNR! Now we were in business, but the 5dB seemed a little too weak forreliable communications, especially with the chance of the tree growing denserfoliage.
I decided a cantenna might be the way to go, so I built a new one using 33.25' diameter cans...this makes the total length about 1.75 waveguidewavelengths. The driven element is 30.75mm long and mounted the 64mm from theback of the can. The conical collector is 7.25' in diameter on the bigside, w/ a 30degree flare. This was just a quick prototype so I made thecollector out of 2 coat-hanger circles, separated w/ four 4' long coathanger supports covered in aluminum foil. the final design will need to be moredurable to stand up against wind & hail. Here is what it looks like:
Before trying it on the target site, I did some testing with my AP at home. Hereare the SNR's I got across the street from my AP:
ORiNOCO built in: 26 dB
2 cans w/o collector: 36 dB
3 cans w/o collector: 37-38 dB
Trevor Marshall biquad: 39 dB
3 cans w/ collector: 43 dB (!)
This is the highest gain antenna I've built yet. In my excitement, I dragged myJornada off a table while connected to this %$* thing and it fell on the floor.Lucky the card & Jornada are ok, but I broke off the end of my pigtail.
The next morning, I climbed on my bro's roof armed w/ the bazooka cantenna.Going back to the same place I got the 5dB SNR w/ the biquad, the bazooka got8dB. I fired up PocketIE on the Jornada, and was able to surf a little -paydirt! Since it was daylight this time, I was able to try out more places onthe roof, and finally found one clear of the tree which yielded 12dB SNR. Nowwe're in business; I've got a little more margin to play with so when I hook upthe long LMR-400 cable to get the signal inside the house I won't get killed byattenuation.
To be continued after I get the rest of the equipment to complete thesetup...
In the meantime, I played with the bazooka from the deck of my hillside house,and was astonished to find that it picked up an AP I'd detected while stumblingon the freeway in my car (using my Mobile Mark clone on the dash). Plugging theGPS coordinates in from the freeway into Microsoft Streets & Trips, it turnsout the AP is about 4 miles away! Using the bazooka on at my house, the SNR was8dB (signal ~-88dBm). As a comparison, I also tried the biquad. Using thebiquad, the signal is unstable w/ max 4dB SNR, and it catches the AP for only asecond at time.
Collinear Omni
This antenna has apage of its own.HomeUp
copyright © 2002-2005 lincomatic
Latest version of this document | More articles
Overview
This sector antenna was made from a piece of thick copper wire formed into a 'bowtie' shape (the biquad - with sides 32 millimetres) and soldered to a round N-type connector. The N connector was then screwed into a steel disc about the size of a CD (Compact Disc).
The original prototype (shown) is still in use two years later, and has survived severe storms.
A semi-technical diagram of the biquad antenna | Note - This antenna is for use with 802.11b wireless computer networks or 2.4GHz video sending equipment. It is not for FM / AM / SW / LW radio useage. |
Construction
The connector - N-type
N-type socket round 'through bulkhead' came from R.S. number 112-0773. Packaging says Telegartner (Manufacturer presumably) Type N-Einbaubuchse J01021A1084 Tel +49 (0) 7157/125-0 Fax -120
Hacer Antenna Wifi Biquad Antenna Review
The biquad ('bow-tie' bit)
Biquad Antenna Design
The 'bowtie' section was made from a length of copper at least 400 mm (0.4 metre) long. The wire came from standard twin-and-earth stiff household mains wiring. By holding either end of the wire with a pair of pliers and giving it a sharp tug the wire was straightened. Leaving about 20 mm before starting, the bowtie shape was folded into the wire using the pliers, with the side of each square being 32 mm. The edge of the pliers was useful to obtain right angles. Both ends of the wire end up in the same place once the 'bowtie' is formed. These were soldered together and bent 90 degrees out of the plane of the bowtie, ready to be soldered to the casing of the N-type connector. The 'bowtie' then had an extending piece of wire soldered to it at the point where there is a 90 degree bend joining the two squares together, ready to be soldered to the centre pin (solder bucket) of the N-type connector.
Soldering
We worked out where the rear disc (groundplane) would sit when the N-type connector was affixed to it, and then both extending wires we cut so as to stand the 'bowtie' off the back plate by 18 mm. The centre pin was easy to solder because it has been tinned by the manufacturer. Soldering the other extending wire to the casing was not so easy. It required the surface roughing with sandpaper, and then tinning with a lot of heat until the solder flows. Once the casing and the end of the wire extension was tinned soldering was easy, while the connector body was still hot. At this point the dialectric (the white bit around the centre pin) started to go a bit soft. We were careful not to move the pin, and ensure it was straight before it cooled.
The 'bowtie' and N-type connector assembly, before fitting to the ground plane.
The ground plane
We drew around a compact disc on to a sheet of galvanised steel (about 1 mm thick - but none of use know our steel gauges - think it's 8 gauge) - and marked the centre. We used a pair of tin snips to cut out the circle. Using a 20 mm cone cutter, we drilled a 16 mm hole on the centre of the disc (by putting the 16 mm washer from the N-type connector over the tip of the cutter before drilling the hole stops at exactly the right size. We de-burred the edges of the disc with a fine file.
Assembly
We screwed the 'bowtie' and connector assembly into the hole in the ground plane, tightened it up with two spanners, and then carefully adjusted the 'bowtie' wire until the plane of the 'bowtie' was nicely parallel to the ground plane.
Weather proofing
We have used no weather proofing on these antennas yet. It needs some kind of plastic cap over the front.
Mounting
The antenna mounted on the U-bolt assembly.
These antennas need aiming. We mounted the antenna on a u bolt assembly using the bottom two bolts only. Thus we drilled two holes in the ground plane at the top. Ensuring the bolts protruded only a nut width, and using 2 nuts behind and 2 nuts in front, secured the ground plane to the lower u-bolt
The U-bolt assembly was clamped down hard on the bar, pointing in the required direction.
The antenna mounted on the pole, showing cable tie at the bottom as strain relief for the cable.
Cost
£5.50 for the N connector. The wire and steel disk were recycled. The u-bolt mounting assembly was around £3.00
Warning
Apart from the fact it works really well, no-one has yet popped on their lab-coat and done any high-brow tests on this 'homebrew twig', and of course manufacturers recommend you don't do anything which they don't recommend, or attach non-proprietary stuff to their stuff. Of course.
Hacer Antenna Wifi Biquad Antenna System
Initial tests
Initial tests show that the antenna has a beamwidth of roughly 70 degrees in elevation (vertical) and azimuth (horizontal) planes, and 12 dB gain in the signal to noise ration over the pcmcia card.
Copyleft
Author: Dave Gough
Copyright (c) 2002 Psand Limited. Permission is granted to copy, distributed and/or modify this document under the terms of the GNUFree Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled 'GNU Free Documentation License'.