hello guys,
i need please to know how to build a real antenna for RF modules, not just a piece of wire, but a real antenna ?
An antenna is a piece of wire. Please explain.
A directional antenna ? What frequency ?
If you buy a real antenna from Ebay for 433MHz or 2.4GHz, and you open it, you only find a piece of wire and perhaps a few windings in that wire.
Erdin:
An antenna is a piece of wire. Please explain.
A directional antenna ? What frequency ?
If you buy a real antenna from Ebay for 433MHz or 2.4GHz, and you open it, you only find a piece of wire and perhaps a few windings in that wire.
what i mean is i need it to look good not just a piece of cutted wire !! hope you understand what i mean
for example when u buy an RC car you find an antenna that looks good not a piece of wire that has been cut from a long wire
Most simple commercial antennas are nothing more than a length of wire inside a plastic sleeve.
They may have loading coils or impedance matching networks if the wire length is not a multiple
of a 1/4 wave long .
Some longer antennas can be made of fibreglass rods with the wire being a copper braid placed over the rod
and encapsulated in thin epoxy.
mauried:
Most simple commercial antennas are nothing more than a length of wire inside a plastic sleeve.
They may have loading coils or impedance matching networks if the wire length is not a multiple
of a 1/4 wave long .
Some longer antennas can be made of fibreglass rods with the wire being a copper braid placed over the rod
and encapsulated in thin epoxy.
i got an idea : i found out that i have an old RC car, so i thought maybe i can take the antenno of the remote control and use it here
but the antenna has 2 wires inside, so it will work ? and how to connect those 2 wires ?
I am assuming since you are concerned about "good looks" that this must be a public project.
You could use heatshrink tubing to make your own cover for a proper length wire.
Or, home and hardware stores sell spray rubber coating, it can be found in black and white and is available via order in other colors.
Or, you can order small neoprene tubing to cover the wire.
Or, you can use spring steel wire available from hobby shops. Top it with a colored plastic hobby bead.
Or, you can use copper sticky-back tape cut to the right length.
Etc.
You connect the two wires to the antenna and ground.
Most RCs do not use the same frequency so it is unlikely to work or work very well.
Grumpy_Mike:
You connect the two wires to the antenna and ground.Most RCs do not use the same frequency so it is unlikely to work or work very well.
ok so i must solder it to the hole of the antenna ?
ok so i must solder it to the hole of the antenna
No an antenna has to have a signal and ground like anything else. If there is no specific ground wire then it takes it's ground from the board through capacitive coupling. However, some antenna have a matching transformer in them, in which case you will need to specifically connect the ground of the transmitter and antenna output.
You can't use any old length of wire the wire has to be a quarter of the wavelength of the frequency you want to use. This is further complicated by the face that any wire will have a velocity factor associated with it, typically about 0.6. This means when working out the wavelength to use you don't use the speed of light c but the speed in your antenna say 0.6c.
In practice you will not know this value and so you typically start with something longer and trim for best results as shown by a SWR meter.