The first step in this project happened in class; we were assigned partners and given the guidelines for the project.

My partner Tanica

Me

• The rules
  • Must use a can
  • Must use radiator supplied in class
  • Get a signal below -80db

The rules seem straight forward enough and easy to follow. From the instructions in class I learned that a -70db signal would be considered really good. My mind immediately went to “if -70dbi is really good a -65db must be really better”. The way I understand it the db is a measurement of the percentage of noise in the signal. For example 75db would be 75% noise with noise being static and only 25% useable signal. This has me exited it should not be too hard to improve on these numbers.

Looking for Ideas

As soon as I got home from class I went to my friend Google with the simple question “how to build a homemade Wi-Fi antenna -65db”. This search produces all sorts of ideas from very simple to incredibly complex. The good news is most of them are very low cost or free. From this I found the idea of using some sort of parabolic dish. This can be almost any “dish shaped object” from a metal strainer to a 30 year old satellite TV dish. It is now time to fire off an email to Tanica to let her know what I have up my sleeve. Then off to Craigslist to browse for a free dish network or direct TV dish.

Regrouping

I found several “free” satellite dishes on CL but none close enough to really consider free, so it is on to plan B, anything shaped like a dish. I have wandered all over the house looking at light fixtures, bowls, kids toys and anything else that remotely resembles a parabolic dish. I did not find anything that really caught my eye so it is off to the “Man Cave” to see what I might have out there.

The brainstorm

I am starting to live up to my reputation “Mcgiver”, I found my fish taco wok that I take camping. I saw this on Google, it will work. I experimented with my phone by turning on the Wi-Fi mode and holding it in front of the wok. My neighbor is about 250 feet away and with my laptop I can pick up his Wi-Fi but cannot even see it on my phone, until I hold my phone in front of the dish. It went from nothing to 3/5 bars on the signal. This is exiting!!!

The problem now is, how to mount the can in front of the wok in a way that will not interfere with the signal too much. Looking around I found three pieces of ¼ “ all thread and decided to use those to make a tripod on the front of the wok to hold the cantenna

A bit about me.

When the McGiver show was on TV my Dad would always say this show is about you. I was about 10 years old and spent most of my time building, tweaking and modifying things in an effort to make them work or work better. I had free run of Dads shop, tools and was surrounded by hundreds of acres of sagebrush. Within a 10 minute bike ride I had friends who also had access to tools, shops and Dads with some awesome talents. Within a mile I had 2 Oil field welder\fabricators, 1 machinist, and an electrical company who designed and built wind generators. I had access to all of their scraps tools and knowledge. I have been building and creating cool stuff from leftovers for over 30 years. I have developed a knack for thinking outside the box and making something work or work better.

Parts and tools for the build and test

Now that I have a plan in my head and have gathered the parts and pieces I need Tanica and I can assemble and test this contraption tomorrow. This is all stuff I had on hand from previous projects or brought home from jobsites.

• 1- 18” Wok
• 3- 28” x ¼” all thread
• A handful of ¼” nuts and washers
• 6- ½” nylon bushings
• 1 – 4” plastic cover for an electrical J box
• 1 roll of black electrical tape
• 20 zip ties
• ¼ “ drill bit
• Cordless drill
• An empty can of Busch Beans
• Radiator (supplied in class)

The change of plans (back to plan “A”)

On my way out the door to go to the lab to meet Tanicia my neighbor asked me, where I was going with a Wok? After I explained it to him he told me he had a dish on his house he was not using and I could have it if I wanted to take it off. The Wok idea is now out the window and we are back to the dish.

Preparing the dish

To prepare the dish I used a saws all to remove half of the transmitter from the horn on the dish. I only removed half of it to preserve the angle at which the receiver needs be to hit the center of the dish. I also had to reverse the mounting bracket to get enough of a downward angle to direct the signal at a target on the ground. The dish its self has to point about 30 degrees down to the ground to project the signal at a receiver on the same level as the dish.

Preparing the cantenna

Using the online calculator we calculated the placement of the hole for the radiator (antenna supplied in class) our can measured 3.25” in diameter according to the calculator our hole needed to be 2.49” from the back\bottom of the can.

Proof of concept

The cantenna was attached to the remaining portion of receiver using black electrical tape around the horn of the dish, and then the whole antenna was held by hand and tested for signal strength. Signal strength peaked @ 65, regularly in the low 70’s

A little more permanent

We placed the dish on top of satellite pole, removed the black electrical tape, and replaced it with glue. Signal strength peaked @ -69db regularly around -74db

Why the drop???

We are now wondering why the signal dropped so much. The only thing that changed was the cantenna is now insulated from the dish by a layer of glue, to test this theory we grounded the cantenna to the dish with an anti-static wrist strap. Signal strength peaked @ -66db and regularly around -69db. The King County Metro Bus interrupted our test and we were still in the low 80’s. for some reason it seems to help to have connectivity between the can and the dish.

Still short of the goal of -65db

Falling short of my goal I decided to test the cantenna alone. It measured a disappointing -84db with a base reading of -83db the can I am using has ridges inside it maybe that is causing interference because the smooth cans seem to be in the low to mid 70’s.

The new can

I am now using the most popular can in class, a can of fancy cookies called Pirouette wafers using the same calculator I drilled my hole for the radiator.

Mounting the new cantenna

To keep a connection between the dish and cantenna I used a piece of 2”x2” aluminum angle and bolted it to the cut off portion of the receiver and then used a 6” hose clamp to attach the cantenna to the homemade bracket with glue on the sides for stability

Final test before grading

We are now ready for one last test before the final grading at noon. Holding the dish on the pole we were able to get a measurement between -64 and -66db SWEET!!! I hit my goal right on the nose, now to walk down the street and catch part of a baseball game before the final test.

Final Test

For the final test I used zip ties to attach the pole to the hand rail beside the side walk. During the test I made very fine adjustments in the direction it was pointed and came up with a signal hovering around -64db when I took my hands off of it so it was not moving at all the signal became very stable at -62db with a base reading of -84db. I will take it, for now… in the future I would like to play with this some more and see if I can hit the low 50’s. I also have a place in Eastern WA with a line of site view that I could test this anywhere from 1000 feet to about 15 miles; I would like to see just how far I can push it.

What made a difference?

· Connectivity between the cantenna and the dish

· Smooth sides inside the can

· Holding the dish as still as possible

· The direction the cantenna pointed at the dish

· A Metro bus parked in the way

Want to build your own

· Use my links on the about page to gather more info and ideas

· Find a free dish

· Get your radiator and calculator here

· Think outside the box

· Set a goal and meet it