RF Designer/Engineer Wanted

Thread Starter

Murphy9190

Joined May 18, 2018
7
Greetings Gentlemen,

I am seeking someone who can help design a small transmitting device. It is basically a plug in wall module unit that can transmit 5 specific sequential analog frequency(s) (small sweep) somewhere between 50 kHz and 150 kHz.

The basic details are:
* Small enough to plug into and be held by a standard wall outlet including the transmission antennae.
* Able to transmit 5 sequential analog frequencies
* Must transmit in a square wave waveform (May require a carrier frequency. If so, must be able to modulate the specific frequency(s) over the carrier wave. I will determine this factor later.)
* Transmission range from 50' to 100' radius (or 100' - 200' diameter)
* Will turn on at a specific time and run for a duration defined in minutes, then turn off on a programmed pattern.
* Should have a manual on/off switch, other than that, it is preliminarily considered all functionality can be hard boarded and fixed.

Basically looking for someone who can build a small transmitter. Hopefully someone here has that experience or some idea who might. Any help or guidance anyone can offer will be genuinely appreciated. This is of course a paying project for the appropriate person/people.

Thank you very much for your attention to this message.

Michael Murphy
Mod edit: snipped personal information. Please use PM, thanks.
 
Last edited by a moderator:

Papabravo

Joined Feb 24, 2006
15,791
The frequency is far too low to have an efficient antenna, a half wavelength is on the order of several kilometers, and square waves are hardly the best way to transmit RF power.
 

Thread Starter

Murphy9190

Joined May 18, 2018
7
Thanks but, the spec's are the spec's. Has to be a square wave. Not interested in efficiency, only efficasy. Only need 1-200'. Only interested in efficiency for that range. I'm sorry but, I'm not clear on what "the frequency is far too low to have an efficient antennae means." You probably need to know what the power level needs to be at that range. I'll get that for you.

Are you saying it is not possible?

Mike
 

Ylli

Joined Nov 13, 2015
1,040
Sounds like you want the RF signal digitally modulated with the square wave. For an antenna, the signal could be coupled back into the power line. That's pretty common.
 

Papabravo

Joined Feb 24, 2006
15,791
Thanks but, the spec's are the spec's. Has to be a square wave. Not interested in efficiency, only efficasy. Only need 1-200'. Only interested in efficiency for that range. I'm sorry but, I'm not clear on what "the frequency is far too low to have an efficient antennae means." You probably need to know what the power level needs to be at that range. I'll get that for you.

Are you saying it is not possible?

Mike
It means that the geometry of the antenna must have one of several possible relationships to the wavelength of the radiated signal. A typical antenna for a transmitter might have a length of half a wavelength. The wave length of your proposed frequency range is 2000 to 6000 meters. So you can see the mismatch between such an antenna and your needs is considerable. Trying to push such a low frequency signal out to a small antenna might not even radiate an inch, much less 200 feet. As it stands I would not have much confidence that a solution to your problem even exists. If it does, it will be a very challenging problem. I'm not even aware of any research on small antennas for VLF (Very Low Frequency) signals. I've also never seen an RF output stage that outputs a square wave. Since amateur radio operators can now work in this range, Id like to know if there are any hams who have experimented with this realm.

With respect to power. You could have 10 kilowatts into an antenna with an extreme mismatch, 10 milliwatts radiated, and 9,999.99 Watts reflected. this system would have similar characteristics to a system with an output power of 10 milliwatts and nanowatts of reflected power. That is how important a good antenna can be in ANY RF application.
 
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Papabravo

Joined Feb 24, 2006
15,791
Sounds like you want the RF signal digitally modulated with the square wave. For an antenna, the signal could be coupled back into the power line. That's pretty common.
I did not read the TS original post that way, but I could be wrong.
As the entire BPL (Broadband over Power Lines) debate made abundantly clear; the power lines make really really lousy antennas.
 

LesJones

Joined Jan 8, 2017
3,138
A description of the purpose of this device would be helpful as it may suggest what is needed to achieve the function rather than what the TS thinks he needs to achieve the function.

Les.
 

Thread Starter

Murphy9190

Joined May 18, 2018
7
The goal is to transmit a resonant frequency - I am trying to resonate with something at fairly close range that it's own frequency exists between 50-150 kHz. The reason for the square wave is it has characteristics desirable for this purpose however, I will check to see if a sine wave will work since I am only targeting one frequency/item. I know the power level is a bit of an issue with loss at distance, I just need to create a certain phenomenon/effect within 75'-100'. For testing purposes, might have to have adjustable power until precise phenomenon and range is ascertained.

Hope this helps.

Mike
 

Ylli

Joined Nov 13, 2015
1,040
I did not read the TS original post that way, but I could be wrong.
As the entire BPL (Broadband over Power Lines) debate made abundantly clear; the power lines make really really lousy antennas.
Yes they do, but better than (for example) a 2" square patch under the front of the wall wart.
 

Papabravo

Joined Feb 24, 2006
15,791
The goal is to transmit a resonant frequency - I am trying to resonate with something at fairly close range that it's own frequency exists between 50-150 kHz. The reason for the square wave is it has characteristics desirable for this purpose however, I will check to see if a sine wave will work since I am only targeting one frequency/item. I know the power level is a bit of an issue with loss at distance, I just need to create a certain phenomenon/effect within 75'-100'. For testing purposes, might have to have adjustable power until precise phenomenon and range is ascertained.

Hope this helps.

Mike
This sounds like nonsense. A transmit frequency is just a transmit frequency. ANY frequency can be a resonant frequency for some combination of components including wire (for an antenna), and various active and passive components. Where did these alleged "specifications" come from?
 

Thread Starter

Murphy9190

Joined May 18, 2018
7
Yes you are right papa, but I have a specific target I want to resonate with. Frequency resonation creates certain phenomenon and that phenomenon is a factor of power and duration. It may be I need a carrier wave to modulate the target frequency over, but it's such a short distance I am hoping not. Power is undefined at this point, but the effect I want to create happens in the mW range and I still have to identify what precise mW at 75', which for testing purposes I am looking for adjustable power. At the end of this conversation, I am hoping for someone to say, "Okay, I get what you are going after. I can build that." Then we make a deal, but I am also aware the builder needs more information and we are not at the end of the conversation yet.

Thank you all for your contributions thus far, I am researching the question areas.

Mike
 

Ylli

Joined Nov 13, 2015
1,040
I agree with PapaBravo here. Unless you are able to tell us what you are trying to do, what you are trying to 'resonate', then I don't think there is much else we can do to help you.

Your current description is pretty much useless, and sounds like it is coming from someone who has no idea what he needs. Are you trying to slip in an 'over unity' thread?
 

Thread Starter

Murphy9190

Joined May 18, 2018
7
I am more than happy to disclose everything to the guy or people who say they can build the device, or at least exhibit a willingness to see a conversation through to a logical outcome. It may turn out I don't have any idea what I need, want or am doing, but it also may be I do and this could be a good project for a couple of guys, myself included. Would you disclose full and confidential information broadly in a forum of people with the requisite skill sets to capitalize on it? Has mankind in general garnered that much faith and trust from you? Yeah, you sound like a trusting guy.

Am I trying to slip in an over unity thread? Why would I or anyone do that? I can't envision the net gain there. No, not trying to "slip" anything in and am not up to any other ill conceived or nefarious agendas. You can be suspicious if you want, but there is no reason or need for it. Just looking for the right person/people for a project with a minimum of negativity and hassle. Electronically the project is simple and utilizes shelf technology(s). I need a radio transmission guy who can duplicate a prescribed waveform and frequency at a prescribed range and distance. If I knew all there was to know about that I wouldn't be asking for help.

That's it. If you can do that let's talk in private. If not, well, what are we talking about?

What I am trying to do or resonate with is irrelevant. The purpose of the device is irrelevant. If I gave you exact schematics would you need to know what it was being used for to build it? Of course not. The real question is, can I provide you with the precise specifications you need and can you meet those specifications? Can you build the device or not? If you are the one to build the device, you will know everything including 'what's in it for you' in a financial sense. This is pretty standard protocol for projects of this nature and discussions at this stage. Use a little logic and goodwill here.

If you can't use or exercise logic and goodwill, you're really not qualified to work with anyway.

Just saying.

Mike
 

Ylli

Joined Nov 13, 2015
1,040
Would you disclose full and confidential information broadly in a forum of people with the requisite skill sets to capitalize on it?
No, but you haven't disclosed enough for anyone to properly evaluate the request. Do you want a 50 KHz RF signal modulated by a lower frequency square wave? Or do you want to create a 50 KHz square wave and allow that to radiate, with all it's harmonics? Does the frequency need to be swept, stepped, or constant? Sounds like you don't know, how are we supposed to?

I need a radio transmission guy who can duplicate a prescribed waveform and frequency at a prescribed range and distance.
You have not provided any concrete information about the waveform, frequency, range, or environment.

What I am trying to do or resonate with is irrelevant. The purpose of the device is irrelevant.
No it's not. Knowing what results you are after can have a large bearing on what may or may not be possible.

Just saying.
 

Papabravo

Joined Feb 24, 2006
15,791
@Murphy9190 Just your desire for secrecy is enough for me to conclude that this discussion is not headed to a successful conclusion for either of us. I have had my fill of people with your mindset. Nobody ever generated a meaningful economic return with one single idea. The only way to generate a meaningful economic return is to come up with a process for generating new ideas faster than they can be copied. I've been there, done that, and maybe did it better than most. I'm retired now and only interested in ideas that can be widely disseminated and shared.
 

Thread Starter

Murphy9190

Joined May 18, 2018
7
Thanks YIIi,

So you know, I have to figure some of this stuff out as I go. I am not an electrical engineer by any stretch. I am very clear on what is to be accomplished and am certain this is possible, but there are factors I need to research and others that cannot be wholly identified without testing. So please, bear with me.

Let's say the targeted resonant frequency is 75KHz, but also lets say the targeted frequency, for different reasons, can vary a little. So we want to do a small sweep in a timed duration to ensure we get resonation for a specified amount of time before sweeping to the next frequency i.e., transmit 73KHz for 10 minutes then 74KHz for 10 minutes then 75KHz etc. on up through 77 KHz. In this example, we sweep by covering 5 frequencies - 2 above and 2 below the targeted frequency. This will ensure resonation somewhere for 10 minutes, which is the primary goal and will be fine if the amplitude is sufficient. After testing the sweep will be effectively minimized to a bare necessary range, but today we cannot determine that range without a prototype.

I was originally thinking the square wave would be best for the harmonics properties, but upon reflection, since I can be pretty precise on the target frequency and feel certain we will hit it within the sweep, a sine wave should work however, simultaneous square wave harmonics are not a negative in this effort and other possible scenarios, and there exist other potential applications. I don't know if utilizing different wave forms presents any design/development issues, but would rather have someone familiar with modulation of multiple wave forms than not.

I'm fairly certain we need a carrier wave for transmission distance and range. The carrier wave is a sine wave and only serves to carry the targeted frequency(s) to a specific distance and range. I can specify the carrier wave if need be, but would need to do some research. (I was hoping to talk to someone, explain all this stuff and then they would say,"Oh, okay, we'll do it like this for testing purposes while we sort out the final details. Probably just the kind of guy and thoughts you hate to work with ;-) I am not a frequency specialist. The carrier wave should be one that penetrates material forms well but this is not my area. I do realize the FCC controls all frequencies as we cannot interfere with other stuff etc. but within those parameters there should exist ample solutions.

The targeted frequency(s) then are modulated over the carrier wave -either in a sine or square wave form - to achieve resonation of a desired object within defined distance parameters.

The largest issue(s) I see are the power requirements, miniaturization and transmission and making sure there are no significant FCC issues..

Frequency transmission, generating wave forms and modulation of the same is shelf technology. The Natural Laws regarding resonation are by nature pretty standard and mostly well known for this application, but maybe not so widely understood. The key and goal is the ability to create resonation at range and distance. That's it. For testing purposes adjustable power is probably necessary.

For the purposes of this discussion, I would hope what we resonate with can be considered irrelevant as the primary goal can be defined as the ability to achieve definable resonation (different frequencies) at definable distance and range however, I completely understand it is always better to have the whole picture when designing, otherwise understanding and the ability to contribute is lost. I am fully aware of this. I just can't disclose it all today in this format to unqualified people I have no NCNDA with. Please understand.

In my limited experience, it's an RF issue and perhaps that statement indicates the limits of my experience.

Did I answer correctly? Please let me know if there are more questions and thank you all very much for your attention willingness to help me sort this out on your forum. I genuinely mean that.



Papa, I like and agree with the part ":eek:nly interested in ideas that can be widely disseminated and shared." I like that world and desire to live in it. We're not there yet, but with thoughts and intentions like yours we'll make it. I can't herein give you the whole business model, how this device and other similar devices/technologies fit in and what the overall goal is as I have others to answer to, but I think you would be pleased. I'm not a greedy secretive elitist. About as far from that as you can get actually, but I understand what you are saying and you would find upon examination we are not so far apart.

Thanks for your thoughts.


Mike
 

BR-549

Joined Sep 22, 2013
4,938
That was completely UN-understandable. If you are serious.......you got a long way to go.

Offering ANY advice is useless.....until you come clean.
 
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