Sometimes you get into trouble with word choice doing large scale projects. In the UK they call it an aerial, in the US they call it an antenna. If you pluralize, do not confuse a pair of anthropod antennae with a couple of rubber antennas.
But, despite not wanting to confuse the insect world with IoT, antennas are a big piece of the data transmission puzzle. In simple terms, an antenna (or aerial) is the physical component that sends and receives electromagnetic waves, your device’s bridge to invisible highways of data.
In IoT devices, the antenna attaches to a transmitter or receiver; sending or receiving radio waves of a specific amplitude or frequency. The trick is collecting and converting the radio wave back into an electrical signal that your device can use. An antenna can take different forms. The computer I am writing on has a WiFi antenna inside the screen, which uses the vertical alignment of an open laptop to boost signal.
An antenna does not need to be a piece of floppy wire. Often they can be attached to your IoT device as tiny components soldered onto the PCB. This is common in space-constrained devices. You can have a flat, square or rectangular looking, “patch antenna” for GPS receivers. These are typically mounted on a flat surface, but they might be directional, meaning the device needs to orient to a specific location. You see this in action with satellite dishes (once common, but now falling out of favor due to streaming services).
Why do antennas matter?
Range: Determines how far your signal can travel. Frequency Matching: Must be tuned to the network: e.g., LoRa at 868 MHz, LTE-M at 700–900 MHz. Efficiency: A poor antenna burns power trying to connect. Form Factor: Small devices need creative antenna solutions without killing performance. Shorter antennas = better for high-frequency (like Wi-Fi, BLE). Longer antennas = better low-frequency reception (like LoRa).
What does the length have to do with it?
Resonance: Antennas work best when they are resonant with the radio frequency they’re trying to transmit or receive. That usually means their physical length is proportional to the wavelength of the signal. Most antennas are 1/4, 1/2, or full wave, meaning; as you might imagine, a quarter wave, half a wave, or a full wave in height. These fractions work because they “vibrate” in sync with the wavelength.
It’s not just the wire, the ground plane (the board or metal below an antenna) also affects how long an antenna “acts” … so a tiny chip antenna on a PCB can still be tuned for 868 MHz because the board helps shape the wave.
As you have noticed, the preferred location to site and fix an aerial is up high. This position gives most “real estate” to work within and usually provides better “line of sight” between devices, meaning a lack of obstacles for the signal. We are now moving into mesh networks, “bouncing” signals and routing, so it is better to close this post on a high, rather than adding too much noise and risk the signal being lost.
