I I am a beginner I am currently working on a project that has 9 volt power supply with on-board 5-volt regulation I'm trying to implement 433 megahertz wireless RF link system I would like to get maximum distance I've seen several videos about different lengths of antennas to maximize performance as a half wave antenna I am wondering if I can create a quarter wave antenna say out of coaxial cable and some fittings I would like to use a smaller antenna as this project is going to be very mobile and I'm fearful of the long antenna .it supposed to be a hands-free battery operated device any help someone could offer I would welcome thank you

 

Do you know how to calculate the wavelength of a 433 MHz. signal and divide that number by 4, to get the length of a quarter wave vertical? You will have a difficult time getting more range out of a smaller antenna. If you are willing to go larger there are some possibilities.

 

The simple quick and dirty is a basic vertical antenna. Wavelength is calculated as the velocity of a radio wave in free space / frequency in Hz so roughly the velocity is 300 Million Meters Second / 433,000,000 = 692 mm Wavelength. If we want a 1/4 wave antenna we can divide 692 mm / 4 = 173 mm. So a vertical pole cut to 173 mm would suffice as a 1/4 wave antenna for 433 MHz. That is the crude and simple. The problem is this antenna is omni-directional so whatever power you have radiates in all directions. Using a directional antenna you get more distance but only in a single direction. A Google of 433 Mhz YAGI Antenna will give you some ideas. Also many small 433 Mhz boards have a small loading coil on the board right where the antenna is connected allowing for a shorter vertical antenna. Depends on your board.

Ron

 

Do you know how to dis-assemble a cable and fold shield....back up cable.

If you fold and roll shield back up cable at 1/4 length.......then cut and stripe center lead at 1/4 length........presto.......you have a dipole.

The cable may lie down your back or side. Or use very small cable with fishing pole attached to back pack vertically.

 

Thanks everyone for all your help & suggestions..really appreciate your time.Can I ask another question, Please..Does anyone know is there a way to set up a point to point tranciever for a simple single square wave oscilation circuit..without an adrino .Not sending data characters just want to send on High off low between points.Can this be done with encode / decode IC.

 

https://maker.pro/projects/pcb/rf-beacon-build-433-mhz-rf-transmitter

 

Thank You much appreciated..