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How to Make a Cantenna (2013)

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Re: How to Make a Cantenna (2013)

#21

Post by PaulHoule »

thelastparadise wrote: post #18
adfm wrote: post #3

Wow! We built that thing 22 years ago! Fun to see it pop up like this periodically. Here's a link to the 10th anniversary: https://makezine.com/article/home/food-beverage/pringles-can...

Are you still into antenna making? Where I live, we only have wireless internet options, so antennas are critical infra. Interestingly, its sort of hard to find antennas optimized for specific frequencies. Most affordable options seem to be "wide band" generalist antennas, e.g. 900mhz-6ghz. Meanwhile the nearby tower might have the best signal on a specific band. I looked into making log periodic/yagi antennas and it…

This one is my favorite homemade antenna project

https://w5nor.org/tape/

which I think makes very clear the principle of a Yagi-Uda antenna which is that different sized antennas are above or below resonance so they are behind or above the input signal in phase. The central antenna is driven, the other two are not, but when the frequency is right the phasing of the antennas is such that the signals reinforce each other in the desired direction.

What threw me the first time I built one is the "hairpin" impedance matching network which is a single-turn coil that looks to me (from the viewpoint of DC electronics) like a short circuit so it took a bit of faith to hook my radio up to it and hit the "transmit" button.

Amazingly though I was able to talk to people in Rochester, NY with my 5 watt handheld and that antenna using a repeater on top of a ski resort mountain 80 miles away.

Re: How to Make a Cantenna (2013)

#22

Post by jazzyjackson »

thelastparadise wrote: post #19
arilotter wrote: post #16

Built one of these with my dad when I was about 8, and this was one of the things that got me bitten by the "working with computers" bug.

> this was one of the things that got me bitten by the "working with computers" bug. Do you ever regret being bitten by this bug? I was bitten by it as well, at an early age. It worked out OK for me in that I've made lots of money, but I feel that it's come at the expense of possible greater impact and glory should this neurodivergent mind have latched onto something more "real" instead. I wonder how this experience…

what is more real than distributing and transforming information?

at least in our society money is a measure of impact, or at least desired impact, but of course there are other measures.

I'm a bit puzzled by your perspective because I dropped out of music school because I felt I could make more impact writing software :)

Re: How to Make a Cantenna (2013)

#23

Post by mxuribe »

thelastparadise wrote: post #19
arilotter wrote: post #16

Built one of these with my dad when I was about 8, and this was one of the things that got me bitten by the "working with computers" bug.

> this was one of the things that got me bitten by the "working with computers" bug. Do you ever regret being bitten by this bug? I was bitten by it as well, at an early age. It worked out OK for me in that I've made lots of money, but I feel that it's come at the expense of possible greater impact and glory should this neurodivergent mind have latched onto something more "real" instead. I wonder how this experience…

I was originally going to be a mechanical engineer...but the early time of the digital age put its (more immediacy-driven or maybe dopamine-driven?) hooks into my brain...and, so I finished my university major in the realm of computers. I can NOT complain, as i have made a great life for my family through my career...But now, as i am in my late 40s/early 50s...i wonder if maybe instead I should have had either a non-tech career or maybe only a slightly tech-adjacent (but not exactly tech hardcode) career, and then simply focused on computer stuff only as a hobby/pursuit/interest instead?

I know that i am not alone in this feeling...as i have heard others my age - and who were orignally not going to "go into tech as a career" - cite similar feelings. Maybe its burnout, or maybe i feel that too much intelligence in tech is wasted on getting silly clicks and things (as the famous saying goes about this age's greatest engineers, etc.)...or maybe a combination of many factors (not excluding age). Anyway, yeah, others have such a feeling about *working* with computers. ;-)

Re: How to Make a Cantenna (2013)

#25

Post by flyinghamster »

I still have a couple of cantennas that I made, oh, about 20 years or so ago. There was a coffee shop half a block from me that didn't have any WiFi (owner behind the times), so I set up a WRT54G with DD-WRT as a client bridge, hooked a cantenna to it, and pointed it at the coffee shop. With the cantenna at the other end, I was able to get a solid signal.

These days? With mobile data anywhere I'm likely to go, that's more trouble than needed. Aside from that, modern WiFi isn't really conducive to external antennas.

Re: How to Make a Cantenna (2013)

#26

Post by spiritplumber »

This and a bunch of WRT54Gs bought for five dollars each because they were bricked let me do wifi for my whole apartment building while I was a senior in uni living off campus. Got the best connection I could afford from comcast and basically I became a mini ISP. I charged five bucks a month to 20 people and it paid for my own connection basically. The trick was that my own packets had priority :)

Re: How to Make a Cantenna (2013)

#28

Post by at_a_remove »

mxuribe wrote: post #23
thelastparadise wrote: post #19

Earlier quoted context omitted.

> this was one of the things that got me bitten by the "working with computers" bug. Do you ever regret being bitten by this bug? I was bitten by it as well, at an early age. It worked out OK for me in that I've made lots of money, but I feel that it's come at the expense of possible greater impact and glory should this neurodivergent mind have latched onto something more "real" instead. I wonder how this experience…

I was originally going to be a mechanical engineer...but the early time of the digital age put its (more immediacy-driven or maybe dopamine-driven?) hooks into my brain...and, so I finished my university major in the realm of computers. I can NOT complain, as i have made a great life for my family through my career...But now, as i am in my late 40s/early 50s...i wonder if maybe instead I should have had either a non-…

I would like to hear of this saying about this age's greatest engineers. I have never heard it, but I have often thought of the tremendous amounts of brainpower wasted on the silly and ephemeral in IT.

Re: How to Make a Cantenna (2013)

#29

Post by Cerium »

gdprrrr wrote: post #6
bluenomatterwho wrote: post #2

Wavelength (mm) ≈ Velocity of wave (Mm/sec) / Frequency (GHz) w = v / f We know v will be 300 (rounded up based on the speed of light mentioned above). For f, we need to plug in the Wi-Fi frequency. You could just use 2.4, but in order to be a little more accurate, we will use two more decimal places. For channel 6 in the 2.4GHz spectrum, we need to plug in 2.437. Solving for w yields ~123mm. w = 300 Mm / 2.437 GHz w…

I know you quoted the article, but this equation > w = 300 Mm / 2.437 GHz Has the wrong unit for c, it's missing the "per second"

We can change the units to mm*GHz, then the division by GHz cancels out and we end up with millimeters. I studied this in the USA, so the number we learned was 11.8 GHz*inches.
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