Author Topic: Spray On Antenna  (Read 42646 times)

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Offline tinhead

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Re: Spray On Antenna
« Reply #50 on: February 16, 2012, 11:56:43 am »
i got answer from ChamTech. They don't have any export classification for the Spray On Antenna yet,
so no price available (at least for me, domestic quotation might deliver different result).

I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Online vk6zgo

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Re: Spray On Antenna
« Reply #51 on: February 16, 2012, 01:48:54 pm »
Found an Amateur talking about mobile VHF antenna's.

http://www.k0bg.com/options.html

Quote
Most of the import antennas are rated from 75 to 200 watts. Where these power ratings come from is a mystery. The aforementioned V8000 with 75 watts out will burn up the average import antenna in due time, so you need to take their power ratings with a grain of salt. Even the venerable Larsen NMO2/70 will get warm during long transmissions at these power levels. I used to run 160+ watts out mobile to a Larsen NMO150. Due to the high power heating the whip, it was necessary to change the whip about every 6 to 8 months. Don't kid yourself; high output power levels require a lot of special considerations (more on this later on).

So 75 watts is enough to burn out many antenna's, and the police radios can easily be 110W at 13.8V - more at the maximum battery voltage over 14 volts..

I think the difference between fixed solid metal antenna's and flexible antennas made form helical copper wire or straight wire running inside a fiberglass cover, and various loading coils, is that the copper wire gauge is often thin enough to heat up. In the example mentioned in the article above, the antenna used about #24 wire - that is 0.02" thick. Add skin effect and that is not much copper at all. I took a quick look at the Larsen range and most of the VHF antenna's were 51" long which is very big. I would imagine to reduce that to, say, a more practical 20 inches, you probably do need helical windings and coils.

So it can get hot, particularly if cheap antenna's are used.

Richard.

It looks as if the 51" antennas were 5/8 wavelength unloaded verticals for 144MHz.
A 1/4 wave vertical for 136MHz is around 20",with one for 174MHz proportionally smaller so they could be used.
The police are extremely unlikely to use"cheap"antennas!
If thin wire can get hot,why not the even thinner coating of paint?
Another thing is,k0bg referred to "long transmissions",as compared to Anthony's "few seconds".

I am a bit surprised at the assumption of 100watts as the output for police radios,in any case.
In most cases they have repeaters,so I would have thought about half that!---not that it would make that much difference!
Another point is,how come we have the quoted frequency range of 136 MHz-174MHz anyway?
Many police radios are in the UHF region.
Of course,some are on HF,in country regions of Oz,& they do use 100w!

 

Offline amspire

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Re: Spray On Antenna
« Reply #52 on: February 16, 2012, 02:21:50 pm »
I did a google search for mobile police transceivers in the US.

The VHF band is one of the bands the police use, and the peak power of 110W came from the radio spec.

Of course some police could be using 5W UHF transceivers, but of  those antennas will not get hot.
« Last Edit: February 16, 2012, 02:23:46 pm by amspire »
 

Offline gregariz

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Re: Spray On Antenna
« Reply #53 on: February 16, 2012, 05:46:12 pm »
I could well believe antenna's get hot if they are either inefficient (ie heavily loaded) or off tune.

A good antenna will easily be better than 80% efficient - and most often better than 90% efficient. The reason you often don't get better efficiencies has to do with the quality of feed systems and mounting arrangements.

What told me that the presentation was nonsense was when the claim of transmitting underwater. Its just not possible unless you can rewrite the electromagnetics equations to somehow minimize the conductivity and permittivity of water. And then there was the stuff about nanocapacitors finding their happy place.
« Last Edit: February 16, 2012, 05:54:18 pm by gregariz »
 

Offline MarkS

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Re: Spray On Antenna
« Reply #54 on: February 16, 2012, 09:27:07 pm »
i got answer from ChamTech. They don't have any export classification for the Spray On Antenna yet,
so no price available (at least for me, domestic quotation might deliver different result).

Yeah, you may have a problem considering your location. :/
 

Online vk6zgo

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Re: Spray On Antenna
« Reply #55 on: February 16, 2012, 11:54:29 pm »
I could well believe antenna's get hot if they are either inefficient (ie heavily loaded) or off tune.

A good antenna will easily be better than 80% efficient - and most often better than 90% efficient. The reason you often don't get better efficiencies has to do with the quality of feed systems and mounting arrangements.

What told me that the presentation was nonsense was when the claim of transmitting underwater. Its just not possible unless you can rewrite the electromagnetics equations to somehow minimize the conductivity and permittivity of water. And then there was the stuff about nanocapacitors finding their happy place.

Off-tune shouldn't normally make the antenna hot--more likely to make the  feeder hot!(see my previous posting--AND disclaimer--I'm not an antenna guru).
Yes,my feeling is we can't "cherry pick" the things that might be possible "If we stand on one leg,scrunch our eyes up,just so,& peer over our left shoulder".
The presentation is full of inconsistencies,& should be judged in its entirety.

 

Offline amspire

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Re: Spray On Antenna
« Reply #56 on: February 17, 2012, 03:07:14 am »
The presentation is full of inconsistencies,& should be judged in its entirety.
I think the presentation was full or errors, including experimental errors, but I can see no evidence at all that Antony Sutera lied about anything. It is not hard to see how the underwater results could have been wrecked by a very simple error - when he added the spray to the antenna, it turned the radio ground into an antenna by somehow coupling the antenna signal connection to the water (ground), and the transmission was happening in air, not in the water. It looks like the police antenna he touched did get hot (not a lie), the tree antenna could be explained by the fact he could have been comparing a tree dipole to an untuned wideband miniature antenna. He never said what he was comparing it to. The iPhone improvement? Well how did he actually measure the signal strength? Say the iPhone test with the paint was several days after the test without paint, the difference could have been the atmospheric differences at the time. Anthony actually said he was expecting the spray-on tree antenna would have 70% the performance of a commercial antenna, and was surprised how well it appeared to work for him. That is probably a true statement.

I don't think he is a scammer - you just don't pick a market that basically consists of a small number of the biggest organizations with the best labs and the best lawyers with unlimited legal budgets to scam. If you are going to be a scammer, you pick a vulnerable market with huge numbers of victims.

Lets get real - Chamtech is a tiny company with 4 employees and an annual budget reportedly of $320K. They make a spray. They don't make antennas, radios, mobile phones, or any electronic devices that I know of, and almost certainly they don't have the money for a decent RF lab. They probably have almost no income yet, so they are extremely vulnerable.

They are a spray paint manufacturer. I doubt that Anthony has any electronic qualifications, and the company may not have a single RF engineer in those 4 employees.

They make a spray paint that was probably initially designed to DARPA requirements, and they want to get in the door of DARPA (US Military), Apple, Samsung, HTC, Motorola, etc.  They probably only have the budget to make a small number of cans, and my suspicion is they actually don't yet have a patent on the spray technology yet. As far as I can see, the only patents they have are some speculative patents of antenna design patterns that I cannot see standing up in court. Basically, the only future the company has is if they have a real product that has useful electrical properties.

The "Solve for X" presentation looked like it was a weekend's work (probably was) and looked like it had all the mistakes that a non-RF engineer could make when trying to test antenna performance on the cheap. It definitely is not the rigorous study we would expect from an engineer, but to me, it matches my expectations for a spray can manufacture trying to test antenna performance. They should do weeks RF anechoic chamber testing to measure the exact properties of the material, but they probably cannot without the resources of a bigger company.

Again I really have to totally bag the technical bloggers - particularly all the ones who turned Anthony vague single test results claims into total fact - that is really, really stupid. Many of the blogger made claims that went beyond anything Anthony actually said.

I just think people are making the mistake of expecting a spray paint manufacturer to behave like a professional electrical engineer with 20 years plus  of lab experience. Based on the impressive product at Anthony's previous company (Aero Performance), I am prepared to believe that this is an attempt at a serious product. Whether it is actually useful or not will be decided by a tough and experienced market that I cannot seriously believe will be a victim of any scam. If this presentation manages to get DARPA and companies like Apple to test this spray, then good luck to Chamtech. That is all they seems to be after. I really cannot see them selling this spray on the late night shopping channels along side the ab toning machines. There is just nothing in that presentation that has harmed anyone.

If the spray turns out to have some interesting electromagnetic properties that can be used, then it is a very worthwhile product. Perhaps if screen-printed over the top of a transmission line on a PCB, it changes the transmission line properties? That would be fun to play with.

Chamtech are a tiny company having a go, and I wish them well. "Give'em a Fair Go" as we say here in Oz.

I most certainly don't see it as my duty to protect Apple and the US military from the possibility of being scammed - they don't need my help.

Richard
 

Online vk6zgo

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Re: Spray On Antenna
« Reply #57 on: February 17, 2012, 06:43:44 am »
Ok ,Richard,I'll leave Anthony (& you) in peace,we've pretty much done this subject to death!
 

Offline Simon

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Re: Spray On Antenna
« Reply #58 on: February 17, 2012, 06:53:56 am »

I don't think he is a scammer - you just don't pick a market that basically consists of a small number of the biggest organizations with the best labs and the best lawyers with unlimited legal budgets to scam. If you are going to be a scammer, you pick a vulnerable market with huge numbers of victims.



what like perpetual motion ? I had the idea of perpetual motion when I was 15 and naive and soon figured that if it really was viable someone would have done it and that it was physically impossible - look at all the adult people that get scammed though........
 

Offline G7PSK

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Re: Spray On Antenna
« Reply #59 on: February 22, 2012, 09:03:36 am »
On the local TV news last night, The University of Bedford in UK have developed a radio wave energy harvesting system.

The unit they demonstrated was a large coil forming a canister about five inch diameter with six smaller coils inside it onto this they had mounted a cheap electric alarm clock with a dummy battery that contained the electronics. Radio waves gave enough power to run the clock, From coil size and what they were saying I think they were using the medium wave transmitters for power.

 
 

Offline Simon

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Re: Spray On Antenna
« Reply #60 on: February 22, 2012, 12:36:56 pm »
The unit they demonstrated was a large coil forming a canister about five inch diameter with six smaller coils inside it onto this they had mounted a cheap electric alarm clock with a dummy battery that contained the electronics.

a far cry from a bit of spray on stuff and all it can really power is a minuscule load, a tiny solar panel would do better
 

Offline G7PSK

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Re: Spray On Antenna
« Reply #61 on: February 22, 2012, 04:23:00 pm »


a far cry from a bit of spray on stuff and all it can really power is a minuscule load, a tiny solar panel would do better
[/quote]

I agree a solar cell would be better built into the clock face something I have already seen, but the university of Bedford has 2 patents on this and just received government funding. I am not sure that the BBC will be happy with thousands of these all drawing power from their transmitters, After all it all be increased loading on them and they will have to up the power, and power costs.
 

Offline Simon

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Re: Spray On Antenna
« Reply #62 on: February 22, 2012, 05:23:30 pm »


a far cry from a bit of spray on stuff and all it can really power is a minuscule load, a tiny solar panel would do better

I agree a solar cell would be better built into the clock face something I have already seen, but the university of Bedford has 2 patents on this and just received government funding. I am not sure that the BBC will be happy with thousands of these all drawing power from their transmitters, After all it all be increased loading on them and they will have to up the power, and power costs.
[/quote]

A government grant ? oh for fuck sake what is the matter with this stupid government, don't they know the basics of physics......
 

Offline IntrepidN00b

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Re: Spray On Antenna
« Reply #63 on: February 22, 2012, 05:55:15 pm »
If i were a small company like Chamtech, stumbling on a revolutionary product like this, the first thing I'd do would be calling the physics department of a local university to get some testing done  by people who know what they are doing.

Also if it holds water a few scientific articles and a co-op venture with a Uni will help with the patent applications and credibility of the product.

it smells fishy to me with my limited understanding of RF and the laws of nature. However I do know that the nano tech world with new high tech materials that are coming have some very exciting possibilities. So it isn't quite out of the question. Just the other day we had the one single atom transistor on Ars Technica, as a point in case.

Good luck to Chamtech and if their product holds water I'm looking forward to a 2 day instead of 1 day battery life on the iPhone 5 and better coverage than Iridium Satelite phones no matter how I hold my iPhone ;-)
 

Offline Simon

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Re: Spray On Antenna
« Reply #64 on: February 22, 2012, 05:57:16 pm »
I think he is just spouting about nano technology without knowing a thing, so he showed a close up / microscope photo - big deal, did it prove anything ? NO !!!
 

Offline G7PSK

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Re: Spray On Antenna
« Reply #65 on: February 22, 2012, 06:16:23 pm »
The trouble Simon is we have not had a governed that knows anything about anything for for at least 60 years.  most likely the world over, politicians go straight from university or even school to politics they have not had real world experiencing.
There should be an age limit, something like you have to be at least 50 before you can go into politics, that way there might not be so many backsides talking. 
 

Offline Simon

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Re: Spray On Antenna
« Reply #66 on: February 22, 2012, 06:17:29 pm »
I thought they paid expensive consultants to sort that out
 

Online MikeK

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Re: Spray On Antenna
« Reply #67 on: February 22, 2012, 06:19:13 pm »
If i were a small company like Chamtech, stumbling on a revolutionary product like this, the first thing I'd do would be calling the physics department of a local university to get some testing done  by people who know what they are doing.

Not if you're a huckster, you wouldn't.  Sutera is the CEO of ChamTech and has been trying to get approval for a combat training site in Utah.  He wants investors and support, not scientists with their messy facts and analysis.
 

Offline G7PSK

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Re: Spray On Antenna
« Reply #68 on: February 22, 2012, 06:39:41 pm »
I thought they paid expensive consultants to sort that out

They do pay expensive consultants to defraud the public, police arrested four the other day, perhaps things are catching up at last on these crooks.
 


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