Domino60

Hi all,

I'm a new member on this website and as a RC airplane beginner I'd like to make few question about the Radio T/R Range and FPV Range.

I saw many videos and read a lot of info about how a airplane works and all the systems as a beginner my 1st airplane is a homemade Foam airplane which I'm building my own Rx/Tx system
so I wanna ask about the Antenna ranges.

I know that here is different types of antennas small and big dbi but there is a question that no one answered me till now so I hope you do.
As an example I have my ground Transmiter which i control the airplane and the airplane receiver both of them are 2dbi which give me a small range but what If i upgrade my ground antenna with a
Helix one and leave the airplane antenna the same. As you know the antenna from the airplane receive so for the ground antenna "Helix" which have a really long range (depend on the mW/W) will transmit without
problem but what about the FPV one? If we do the same thing.

Here is a video of a guy who did that:
https://www.youtube.com/watch?v=yUm3_e-Umhg&list=LLUNvg9PtBCzfdBN74TIoFFA&index=1 As I know the Transmiter on the FPV in on the airplane and it's only 200mW and on the ground he had a Parabolic Helix, how could he receive from that long range?
Here is where i don't understand, even if we got a small range transmiter and in the other way a huge range receiver the receiver can receive data from the transmiter?

jester_s1

Antenna design has a lot to do with the range. Receiver antennas have a boost rating, which is how much improvement in reception they give you.

Now with that question answered, I'm going to answer the question you didn't ask, which is whether or not building your own radio gear is a good idea. The answer is "no." For one, you may be breaking the law by building a non FCC approved transmitter. You may need a license to operate what you've built depending on what it is. And that assuming, of course, that what you've built is reliable. RC vehicles can do substantial damage when they crash into things, and you'll be liable for that. Good reliable radio gear isn't expensive anymore, so buying commercial products is the way to go. If you are an electrical engineer who already understand the radio equipment on the market and its limitations and wants to improve on it that would be different, but if you were an electrical engineer you probably wouldn't be on RCuniverse asking about antenna design. All of my comments are moot if by "building" you actually meant hooking up the wires on a commercially produced radio.

And one other thing: are you observing proper safety guidelines for operating your drone? The AMA put out a solid guild on how to do FPV safely, and if all pilots observe it the RC hobby will manage to stay out of the evening news. In a nutshell, you should use a spotter, never fly over people, don't fly over other people's property without permission, and don't fly farther away from yourself than you can see the vehicle. I'll add on to that that you shouldn't take off with FPV gear unless you have a flight controller with a return to home feature set up as a failsafe and also as a switch on your transmitter.

I hope you understand that I'm not trying to be unfriendly to a new beginner in our great hobby. RC is very rewarding if done safely. But FPV and multirotor aircraft have opened up possibilities that didn't exist before to do it very unsafely, Add to that the maker movement that is going on and a general attitude of individuality among young people, and we have a recipe for disaster. The hobby has already taken many hits from irresponsible pilots with multirotors, even to the point of the FAA proposing some pretty harsh regulations on the hobby for the first time ever which has created the need for the AMA to spend a boatload of money to lobby congress on our behalf. I want you to enjoy the hobby, but I don't want your enjoyment of the hobby to cost the rest of us the freedom we've enjoyed for decades. Be responsible, pay for good equipment, and learn the safety guidelines so you can have a great time with the hobby too.

Domino60

I'm an IT engineer programmer and as hobby electronics and programing microcontrollers/ making my own PCB's and RC hobby.

About the the radio is safe, I'm using 2.4Ghz modules which I'm gonna make my own radio Tx/Rx, about of where I'm gonna test the airplane i have a great +1 square Km clean field which I can test the airplane under low altitude.
Yes of curse I have a GPS / Compas module inside which I'm gonna program on my own to get the airplane position and get it back home if (There is no response from the ground, low battery, far away from base or if i press to come home), the airplane will be totally safe, will have a self stabilizer in case of high wind or error control / no signal. About the FPV at a radius of 3Km there is nothing around only GSM antennas but i can change the Band so it will not cause any truble to phone company and the final as a test I will fly the airplane no higher than 100~300meters.


So in the RC hobby part I'm a fun and start searching about everything to understand how everything works but never gave a try to build something to fly (I had a cheap helicopter when i was kid, still have it but it's too old to make it fly 25cm helicopter). Now I gave a lot of questions about antennas (I know how in general they work) but it make no seans in my brain about how a radio for airplane work and how FPV radio works.
The Control radio, you have the transmiter to transmit data to the airplane and control it but the FPV you have the receiver to receive Audio/Video, yes that makes sense, what doesn't make sense to me is how can you put a better antenna on the receiver and get more range if the transmiter is low mW and can't transmit more than 1.5Km (as example). And does the module need to support the exact dbi to get a antenna? if yes what dbi is a helix antenna? or as helix antenna that doesn't mater?

jester_s1

You'll be a lot better off buying a commercially produced radio and a controller like the Ardupilot for at least your first attempt. Starting with a successful design and then looking for ways to improve it makes a lot more sense to me. For that matter, you can build your own Ardupilot if you want to because it's open source. You can get the board schematic from them and download their firmware for free. As for antennas, the weakest radios used in our hobby with transmit farther than that. It's how much noise is mixed in and how weak the signal gets that limits the range. I couldn't tell you how one antenna design is better than another, but I do know that tiny differences in the shape and design can make a big impact on the range of these 5.8ghz systems.

Domino60

Why should I buy something ready when I can build on my own?
My project have few steps, one step is to make a basic airplane to fly which gonna be the 1st attempt to see if the actual homemade airplane and rx/tx that i builded it's working on a 100metre range as testing.
2nd step is to make to balance itself in the air using a Acceleromiter/Gyro combined/filtered and making it to control the servos/the airplane and final step (I wouldn't say it's final) is to make the airplane to get
GPS data and make it fly a trajectory, to not get out of the field range and to return to base, of curse there is many options you can program the airplane using the GPS data. And of curse I'm gonna put other great sensors
and safety switches.

I'm gonna use 2.5Ghz to control the airplane (Homemade joystick, buttons (for different options), LCD for data).
and 5.8Ghz for FPV, with basic SMA 2dbi antennas I will get approx 500~1000m range, as a test it's really nice range but in the future i wanna upgrade the antennas to polarized (for the airplane) and Helix for the ground
station.

So following Step by Step and each Step will be tested in a range of 100~300 meters. For this airplane I'm building now I will be glad to have Crystal clear FPV and RC at max range of 2Km. That will be enough for
me in this type of airplane.
Btw Homemade airplane specs: 1 meter long, 2 meter wing spawn, ~2 Kg Flying weight, Motor thrust 1~1.5Kg with 10inch Carbon fiber prop.
The only part is missing from my components list is my FPV setup, need to buy Rx/Tx, battery, camera and OSD (but as beginner i will skip the OSD and probably gonna buy it later).


So I would be glad to get some advices.


Domino60.

FLAPHappy

My Feedback: (209)

I would follow Jesters remarks. I did watch your video, very impressive, but one thing is clear.
You violated the Altitude Requirements of the FAA and the AMA, the last part I viewed, the plane was at 540 Meters. The Altitude Limit in this Country is 120 Meters or 400 Ft. I wouldn't be broadcasting your invention all over the internet, because Drones are in a lot of Hot Water right now. Just friendly advice.

Domino60

It's not my video, I gave an example of Helix antenna a guy using with 200mW transmiter FPV and got 19km range, THIS VIDEO IS NOT MINE.
Not use which country you talking about, America?
Drones are in hot water too by American Army in Iraq,Iran, Pakistan..etc who kill more than 2k people per year. Just a hobby flying a airplane is not so big deal because you don't load rockets to kill people.

About the Jester remarks I would follow too if i was unexperienced hobbyiest but in this case I will build my own system.

FLAPHappy

My Feedback: (209)

Yes, I am talking about American Drone Hobby activities in the U.S. I don't know where you are located, it doesn't matter, but if in the U.S. it does matter. You were asking questions and we gave you a couple of suggestions is all, no big deal.

Domino60

Cool.

My question here is how exactly I pick antenna for my modules? I know that my module support :

How do I pick the exact antenna? Picking Polarized antenna is not hard but what about Helix? I just take the antenna and plug and play or they came with an exact dbi?
I looked on internet shops and they have only 5.8Ghz Helix
Btw from the table, Maximum output power, that means my module support 20 dbi?

How do i pick antennas in general? I just take what ever antenna I like (small, big) and plug it?

jester_s1

You are an inexperienced hobbyist, Domino. You haven't done this before. You probably won't do it as well on your first attempt as those who have gone before you. The best case scenario is that you reinvent the wheel and learn how it was invented to begin with, which you could also do by buying a commercial product and studying it. The worst case scenario is that your designs don't work and you lose your aircraft or hurt someone. I totally get wanting to do original work and having the urge to tinker, but if you actually want to innovate you need to understand what's already been done before.

To drive home the point, my club hosts the SAE aero design contest 2 out of every 3 years. Maybe you've heard of it; it's for senior engineering students at universities. Teams from all over the world come with their designs to do a heavy lift contest. The schools that do well study the designs that have won before along with their own designs from previous years and then do what they can to improve them.The winning team last year was using an OS .65 engine and had a takeoff weight of 42 pounds. Normally, that engine is considered appropriate for an 8-10 pound model, so it was quite an achievement. But there were other teams that didn't do quite as well. About 10% of the teams show up with a completely novel design, having ignored previous designs because they want to do it all themselves, and I watch most of those planes go all toothpicks within seconds of taking off. The difference is the engineers who are willing to use the work of others who have gone before them and then innovate on top of that versus the ones who get their egos involved and think that their creativity trumps other's knowledge. A good number of planes at SAE show up never have even been test flown because the team go bogged down in the details of their novel design and didn't have time to actually see if any of it worked. Occasionally they do well anyway, but usually their planes don't even complete a single lap around the airfield.

So my point is that if you want to be successful, start with a known working configuration and then use your engineering skills to make it better. Evaluate what you like and don't like about the design and see how you can improve it. If you do that, you might wind up being the guy who comes up with the next big thing in the hobby and design something we all wind up using in a couple of years. I think that would be a better goal than lawn darting your first effort and not even knowing why because there are so many untested systems trying to work together.

rgburrill

Domino, I don't know where you are located but most of the world has something akin to our FCC that controls transmiting equipment so as to not interefere with other people. If yu are operating on our equivalent HAM radio frequencies then more power to ya. But if you are taking your IT background and just willy-nillly building a transmitter to operate in any frequeny you desire I hope you get caught and shut down very quickly, before you hurt someone.

Hydro Junkie

I see some things that concern me to no end:
1) You have said what you are wanting to do and asking questions but have not told us where you are so we don't know if US law applies or not so we are just guessing
2) You have said that you are going to use a 2.4 MHz module in one post but then in a later one say your are going to transmit on 2.5 GHZ. In the US, your second post says that you are going to violate two separate FCC laws, illegally modifying a transmitter module and transmitting on an illegal frequency
3) You said in one of your posts that you were going to test fly your plane using GPS and program it to fly to a point and return on it's own. This is also illegal in the US since it becomes an autonomous drone and is no longer an R/C aircraft.
4) You have asked for help and yet you refuse to listen to the sound advice being given. What good would it be to just answer your question without knowing if answering it would put us in jail for aiding a felon, something that you may be if you follow your plans as given
Before you consider taking this project any further, IT WOULD BE HIGHLY ADVISABLE THAT YOU CHECK WITH LOCAL GOVERNMENT AGENCIES TO VERIFY THAT YOUR PROJECT IS NOT GOING TO BREAK ANY LOCAL OR FEDERAL LAWS

Domino60

If you are talking about the airplane design I made a search of months and month how a airplane works..etc and I came up with a great design and help from a airplane 3D designer which we could see the actual plane till I
build it. About the Radio control I'm using a system that electronic hobbiests use and I approve it to use it on my Airplane, the same system/RC module has been used on quadcopters so it's working really well, the range will not be really big but I know what I'm doing step by step. I need this model as a demonstration because it's my final year project so that's a secret why I'm doing all by myself and don't buy already made.

WOW calm down
The Transmiter/Receiver is a 2.4Ghz 6 channel and the test aria I'm gonna test my airplane is a local +1 square Km ground which is for RC airplanes. So tell me how could i hurt someone?
From this aria the airport is about 20Km away my range will be 500meters and the closest and only GSM company antenna is at 300 meters away and the final part in that 1Km aria there is no one, is clear field.

1. I'm not in US but I'm somewhere in Europe I would not like to say where exactly I am, for personal things.
2. Probably it was a hand writing mistake, I'm using a 2.4Ghz, about the module is a 2.4Ghz Transceiver chip so by the company who build it is allowed for electronic hobbiests to use it and program it as they like.
3. Well in US as a freedom country, I don't see any freedom there (No offence) the way I'm gonna program it and test it with GPS will be under my control and visual, the testing will not get out of the field and 500 m testing range
and this project is Approved by my University as final year project so I'm totally covered.

About the final part to search the local Gov. Age. I will do that because I'd like to know too.


So the final part i was asking about the Antennas so hope I answered your questions now is your turn to answer mine

Hydro Junkie

Okay then, me not being an antenna expert, you may be best served contacting people that have and operate ham radios or look at them over the internet. As for a standard R/C 2.4 antenna, the unshielded length matches the wavelength of the signal so that may be a place to start

Domino60

Ham radio? I know the device but what that have to do with my radio control and fpv?
Well i looked on internet about ham radio antennas but are kinda big and small scale, ham radios working with Low freq. which allow them to have a really big band.
As I know band is the freq. which is measured "band" cycle of wave length.

as the image above. Lower Freq. higher (far) band, higher freq. smaller band.

Now I know that I'm using 2.4Ghz Radio what i need to know is how exactly do i know which antenna to take to change the standard antenna and get bigger range.
I know that each Radio device support some kind of antenna max and min, which as i know is the dbi,db which stand for that but I can't understand the difference between dbi and dbm, my device
had 2dbi antenna and the description says "max power +20dbm" how do i know that's the max antenna I can put on my device?
All online shops sell antennas with the dbi mark.

Another thing that i know you can increase the transmition or receiver with a Helix antenna and Parabolic antenna which focus all the radio receive/transmit and get more range/data (Kb/s).



So the simple question is what do I look / calculate to get a max powerful / compatible antenna for my device / any device?
As example:
I'm a computer engineer and I know that till you build a new computer you need to search the exact components and compatible ones with the motherboard you pick..etc

Hydro Junkie

Try this, it may help:
http://www.daycounter.com/Calculator...lculator.phtml

Domino60

Well that helps to build a homemade Helix, thanks but what about the device compatibility, how can I know what antennas support and what max dbi ?

Hydro Junkie

Sorry, can't help you with that one, don't have to knowledge or experience

dirtybird

My Feedback: (5)

DBI (DB Isotope) The gain of an antenna relative to a single linear antenna.Db's are a unit of gain or attenuation.They have no absolute value. DBM references the value to 1 milliwatt. 3db is a gain of about 2. 10 db is a gain or loss of an order of magnitude
If you have 30dbm it is 1 watt
Your antenna will have to be matched to your output stage. The Ham people know more about that than most people even engineers.Perhaps where you buy it will tell you

Domino60

I don't think on online shops they gonna tell me something

Well thanks for explaining me some stuffs but to me looks like chines
I need something like full explanation to understand.

rgburrill

Ham is a term for amature radio operators. They have specific frequenciy bands to operate in which are different throughout the world. They have licensing requirments so they understand how radios work so they can, indeed, buy a chip and buiild a transmitter. BUT, I repeat, they are licensed to do so for safety of the general public. Since you do not know what a ham operator is you are likely building something illegal. And I sincerely doubt that any ham operators on this forum would be willing to help you in this endeavour.
Several years ago 72MHz was the primary RC aircraft frency band used in the US. It was divided into many channels to allow several people to fly at one time. Teh channels were easily changed by a crystal on the front of the transmitter and one in the receiver. And time and again there were discussions on this forum about how radio manufacturers would state in their manuals that changing frequcnices, especially over a large number of channels required sending the transmitter back to the manufacturer to adjust the output coupling to the antenna. It takes special equiment - do you have thousands of dollars to spend on RF test equipment?
It's been shown time and again that many people can learn to fly a real plane on a simulator. They can also read the manual on a specific. And they can actually fly a plane without being licensed. That's not only illegal, it is stupid.

Edit: I should point out that the reason hams have specific assigned frequency bands is because if they screw up a build they only affect each other, not the general public.

dirtybird

My Feedback: (5)

It is my understanding hat you are using legal equipment and just want to increase antenna gain.
Here is what looks like a great antenna:
http://www.dsstyles.com/product/gopr...FRCqaQod5i0MIw

Domino60

rgburrill I did not said that I use illegal modules, I don't think RC manufactures sell illegal 2.5Ghz module, I understand your point but this module is need sold to be programmed by other people
who wanna use it on their own purpose, is it 2.4Ghz 6ch.b. So in any case i will not get anything or doing anything illegal using this module.
I'm not from US but I really don't care about legal or illegal, that worlds can be changed every day buy different kind of facilities, industries, Gov..etc
You are legal to use today your phone but tomorrow you are not so all that bull**** about legal or illegal ain't affect me. We live on a planet that we all have the same rights to use anything as others do.
Yes of curse i will be careful not harm people because I'm not a killer (from example use the same freq as airplane and they will not have contact with the ground) yes I totally understand that but
in any other case that FPV or flying or what ever is not legal to do who cares, My airplane don't kill people like US RQ's do in Iraq,Iran..etc It's just a hobby airplane that i like to fly and have First person view
from the airplane for better control as a video game + it's better to orientate your self and not lose control.

I've been 5 days doing deep research about radio communication and how they work so I know extra stuffs from other forums too.
As an IT engineer/ programmer and electronics hobby I can do amazing stuffs and no one can tell me that i can't.

FLAPHappy

My Feedback: (209)

OK, Now we know you are a well educated ENGINEER, and you can do amazing" stuffs " as you put it, then you don't need any help from anyone, because you have all the Answers. Legal or Illegal? Wow, you are in trouble right there. Your last sentence gave it away, a Troll is AMOUNG US!!!!!!!!!!!! Domino just joined RCU this month,no history about this guy,make your own decisions.

Domino60

FLAPHappy, I joined this week rcuniverse website forum to learn more about radio controls and antennas, I know some people get worry not giving band or wrong direction to any kind of person to do
illegal stuffs because that will be a bad for the forum and website. All the components I'm using are (free source to learn) and legal to to use, in the other way I don't like to describe a component or homemade legal or illegal
because that's how all started one day to make computers, smartphones..etc They tested their own ideas / circuits and in the end patented to sell them on the market. All the components that I'm using are made from big manufactures
which one is ATMEL which sell millions of chips per year to AMD, Intel, Apple, Microsoft ..etc So using and experimenting / testing my circuit / airplane i can some day to patent the airplane and sell it as a RC kit.

I came here to learn extra stuffs and clear my brain from unknown answers to my questions. So let's stop talking about myself and let's start focus on the topic.