Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Evolved antenna

en.wikipedia.org

Post reply on HN
Print view View original

51–60 of 69 posts

Re: Evolved antenna

#51

Post by hoosieree »

dnautics wrote: post #41
scrooched_moose wrote: post #39

Earlier quoted context omitted.

Are you aware of anyone who has recreated the process, except with a large pool of different FPGAs from different manufacturers and running designs on a random one each time? I'd imagine with even a moderate pool (~10?) the variation falls away and you're left with a robust design, although the process will take significantly longer.

apparently it is not possible because contemporary FPGAs do not give you low-level access to modify the floorplan.

How low-level do you need? Vivado lets you place individual LUTs where you want, and to some extent dictate the routing.

Re: Evolved antenna

#52

Post by JoeDaDude »

aequitas wrote: post #7

Reminds me of an old article about evolutionary circuit design. The computer was tasked with creating a osscilator using physical hardware. It created a really complex and unconventional design that no-one understood, but it worked, only not work outside of the lab. As it turned out the algorithm had designed it in a way that it used the radio noise from the computer it was running on as a source. It had effectively…

This is the origin of that story. From The Evolved Radio and its Implications for Modelling the Evolution of Novel Sensors

"It seems that some circuits had amplified radio signals present in the air that were stable enough over the 2 ms sampling period to give good fitness scores. These signals were generated by nearby PCs in the laboratory where the experiments took place."

https://people.duke.edu/~ng46/topics/evolved-radio.pdf

Re: Evolved antenna

#54

Post by nomel »

I accidentally "evolved" a microwave antenna in my microwave oven, once.

I put some hematite sand on the top of a glass plate that was suspended about 5 inches from the bottom of the microwave oven. I wanted to see what kind of pattern the standing waves would heat the hematite to (this microwave didn't have an RF stirring fan).

Instead of some standing wave pattern, I ended up with a fractal like antenna that grew from a molten blob in the middle. The initial molten blob extended into arms of molten material, with each arm necessarily extending in the direction that maximized RF absorption, causing additional material to melt. It grew brighter and brighter as it extended, reached some peak, then some of the arms shorted and it dimmed. Then the plate shattered from the heat.

I wrote some software that converted the picture into antenna elements for some free antenna simulation package I found at the time, but it couldn't support enough elements to get close to the shape of the antenna and would just crash beyond 10 or so.

I'm not sure how useful of an antenna it would be, since it was maximized to generate heat, but it was a neat kitchen experiment.

Re: Evolved antenna

#55

Post by bradenb »

nomel wrote: post #54

I accidentally "evolved" a microwave antenna in my microwave oven, once. I put some hematite sand on the top of a glass plate that was suspended about 5 inches from the bottom of the microwave oven. I wanted to see what kind of pattern the standing waves would heat the hematite to (this microwave didn't have an RF stirring fan). Instead of some standing wave pattern, I ended up with a fractal like antenna that grew f…

I would love to see pictures or a video of this in action!

Re: Evolved antenna

#56

Post by taneq »

auslander wrote: post #30

And then there is phased arrays, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. Pure math (matrix of delays per element). Go crazy :) https://en.wikipedia.org/wiki/Phased_array

The same thing is used in ultrasounds (except with sound) which is how they can "scan" without having any moving parts. Super cool.

Re: Evolved antenna

#59

Post by heavenlyblue »

dbcurtis wrote: post #9
walrus01 wrote: post #3

Evolved antennas are good for certain purposes, but for highly directional links, the laws of physics say that there isn't much better than some variation on a human + CAD + Matlab designed parabolic reflector (whether it's center feed, compact cassegrain, elliptical offset feed, etc). Take a look at the dishes used for 71-86 GHz band mmwave links for instance.

"Better" when the goal is a very narrow beam pattern and minimal side- and back-lobes. That isn't always the goal. For instance, putting your entire FCC city-of-license within your grade A signal contour from X miles away at a bearing of B. Or, in one case I am aware of, covering your puny city of license in one direction, and incidentally getting good coverage into the much bigger city off the back of the beam so th…

Or using a phased array that can generate practically any shape of the signal.
Post reply on HN