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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
A few questions on antennas. im wanting to transmit and recieve abit further without lighting up the neighborhood with 9,000 watts of RF.
Arduino 2.4 GHz device and others at 5.8GHz.
i understand the physics and geometry of the Gregorian method. But not sure how to attach the white part there to the actual wiggle board antenna in the above pic.
Can the Board just go in a metallic horn and shoved in the center dish hole of appropriate wave dimensions ?
Id also prefer a SMA or similar connector epoxied in attached in some way later on.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
The ESP8266 is already able to reach 150m with the bad antenna in that photo. Also, those digital satellite TV dish with a regular wifi base-station transmitter can exceed 3km access with minimal packet loss.
In general the dish gain is based on its diameter (lip edge is a multiple of the wavelength), pole depth (1/4 or 3/4 of the wavelength in air), and focal zone area (most wrongly assume it is a single point illuminating the dish).
Yagi are usually cheaper to deploy, as a large dish can get blown around in high wind.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
the nrf24l01 is pretty robust and i bought 10 for $12, so im ready to lose some. supposedly 200m, 2Mbps though some claim a magical 1000m range at 250 kbps.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
nrf24l01 have better power efficiency (lower bandwidth => less power), but require a host controller to run them correctly. We dumped these because the networking stack is very limited, and only compatible with similar devices.
The wifi/BLE + dual core + low-power-mcu ESP32 has enough RAM and program space with Free RTOS to do quite a lot. We ended up using these as the hardware SPI port buffer will do >20MHz with ease, and the SSL sessions are actually possible (the esp8266 can only handle 1 SSL client at a time for example). Modules are usually under $5, and USB port developer boards under $6.
A word of advice, use Ubuntu 16.04 LTS to setup the C++ SDK + firmware-loader for the demo software examples.... or it can get really flaky to configure the build in Windows even with the Arduino IDE (if the core features are even completely ported in yet).
nRF modules are not the easy solution for most setups > 8 nodes.... =)
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Gregorian Dish Antenna.
