Electronics Transmit RF signals directly to receiver in line of sight

[TechTree]

Hello, I am trying to transmit radio signals across a distance of just under 1km to the receiver. The receiver is in line of sight with the transmitter. I just need to send the data in the most direct way possible, almost like shining a laser through the air. I was wondering what type of antenna would be used in this situation?

Many thanks!

 

[anorlunda]

I imagine that Spain, like most countries does not allow you to transmit radio without a special license.

Contact a HAM radio (might be called amateur radio) club near you. They can give you both technical advice and legal advice. Some of them might have already built something very similar to what you described.

 

[Nik_2213]

Hi !
What data rate ? Is it time critical ??

I've seen pole-mounted multiple Yagi arrays used to relay TV from ridge receiver to village in valley.
I can't remember if this used UHF as-is, or down-shifted prior to re-transmission.

Also, I've seen site CCTV systems 'beam' from masts to base-station's outside antennae...
YMMV.

 

[jim hardy]

Hello, I am trying to transmit radio signals across a distance of just under 1km to the receiver.

i hope you're using a legal apparatus like a walkie-talkie.

I was wondering what type of antenna would be used in this situation?

Depends on the wavelength (frequency) you're using.

WIFI hackers build Tin Can Antennas and plans abound on Youtube. They operate on very short wavelengths/high frequencies. .

I just need to send the data in the most direct way possible, almost like shining a laser through the air. I

YAGI is easy to make and works well .
If you want to get fancy, and have plenty of room. look up "Rhombic Antenna"

Antenna size is on same order of magnitude as wavelength involved.
An antenna may have to be a mile across for a low frequency or just a few millimeters for high one
so your question can't really be answered as posed.

"A question well stated is half answered" .

 

[jim hardy]

Have you thought about modulating a small led flashlight ? You could aim a telescope at it on receiving end.

 

[Borek]

I would start checking existing and ready solutions, like the ones used for telemetry in RC models - something like RFD900 Radio Modem, or much cheaper SiK telemetry radio. While these model are specialized for RC and telemetry they can be a good starting point for finding solution that will suit your needs.

And they don't require any serious external antenna, they come with one that will work at 1 km without problems.

 

[TechTree]

Thank you for all the replies, very informative!

Have you thought about modulating a small led flashlight ? You could aim a telescope at it on receiving end.

That's a very clever idea, I'm curious to try and set something up like that now.

 

[Rive]

The usual solution up to 3-5km distance is some yagi antenna for WiFi. Plenty of guides for homemade types, or you can order some directly from common webshops.
Usually legal (as long as you don't tamper with the output power of the router), but better check the local laws first.