Antenna Selection 101: Fiberglass vs. Magnetic Antennas for LoRaWAN Gateways

The antenna is the "mouth" and "ears" of your LoRaWAN gateway. Choosing the wrong one can cripple even the most expensive hardware. This guide compares the two most common antenna types: the rugged Fiberglass (Collinear) antenna and the cheap Magnetic Mount (Whip) antenna. We dive deep into the physics of "Cable Loss"—explaining why the thin cable on a magnetic antenna destroys your signal—and the "Ground Plane" requirement that most installers miss. By understanding these differences, you can choose the right aerial to maximize your network's range and reliability.

You have bought an industrial LoRaWAN gateway. It probably came with a small black "stick" antenna in the box. Now you are looking online, and you see huge white fiberglass tubes and small magnetic bases.

Which one should you use?

The antenna is the single most critical component for range. A $500 LoRaWAN gateway with a bad antenna performs worse than a $100 gateway with a great antenna.

The market is split between two main types: Fiberglass and Magnetic Mount. This guide breaks down the physics, the flaws, and the use cases for each to help you build a better network.

The biggest problem with mag mount antennas is the cable. They almost always use RG174, a very thin coaxial cable.

• The Math: At 915 MHz, RG174 loses approximately 1 dB per meter.
• The Result: If your mag mount has a 3-meter cable, you lose 3 dB. Since 3 dB represents a doubling/halving of power, you have lost 50% of your signal before it even touches the LoRaWAN gateway.
• The Verdict: The antenna might have "3 dBi Gain," but the cable has "3 dB Loss." The net result is 0 dB. You gained nothing.

Magnetic antennas are "monopoles" (half an antenna). They rely on a "Ground Plane"—a flat metal surface—to act as the other half (the mirror image).

• Correct Usage: Stuck to the roof of a car or a metal cabinet.
• Incorrect Usage: Stuck to a wooden fence, a plastic box, or a window sill. Without a metal surface under it, a magnetic antenna connected to a LoRaWAN gateway will have a terrible VSWR (Voltage Standing Wave Ratio), reflecting energy back into the radio and killing your range.

Best For: Temporary site surveys, drive-testing coverage, or vehicle tracking.

These are rigid tubes, usually white or grey, ranging from 30cm to 1 meter long. They are the standard for professional deployments.

Fiberglass antennas are typically "Collinear Arrays"—a stack of dipoles inside the tube.

• The Advantage: They are Ground Plane Independent. You can mount them on a fiberglass pole, a wooden post, or the side of a brick building. They do not need a metal sheet to work. This gives you total flexibility in placing your LoRaWAN gateway.

Fiberglass antennas have an N-Type connector on the bottom. You choose the cable.

• The Upgrade: Instead of lossy RG174, you can use LMR400 cable.
• The Math: LMR400 loses only 0.13 dB per meter.
• The Result: You can run a cable 10 meters up a tower and only lose ~1.3 dB. Your LoRaWAN gateway hears clearer, stronger signals from much further away.

Best For: Permanent outdoor base stations, high-tower installations, and agriculture.

Fiberglass antennas come in 3dBi, 5.8dBi, and 8dBi versions. Higher numbers mean the signal is "flatter."

• Low Gain (3 dBi): Shaped like a beach ball. Good for hilly terrain or urban areas where the LoRaWAN gateway needs to hear sensors above or below it.
• High Gain (8 dBi): Shaped like a pancake. It reaches very far horizontally but has a "blind spot" directly underneath the tower.
• The Sweet Spot: For most industrial LoRaWAN gateway deployments, 5.8 dBi is the perfect balance. It punches through trees but still covers the immediate area.

A LoRaWAN gateway deployed for a Smart City project must last 10 years.

• Mag Mount: The cable entry point is a weak spot. Water eventually wicks down the braid of the coax and floods the gateway antenna port. The steel whip rusts.
• Fiberglass: Rated IP67. The fiberglass radome is UV stabilized (it won't crack in the sun). The N-Type connector is weather-sealed. It is designed to survive hurricanes and ice storms.

If you are building a proof-of-concept on your desk, a magnetic antenna is fine. But for a production network, it is a liability.

The combination of high cable loss and ground plane dependence makes magnetic antennas unsuitable for critical infrastructure. By investing in a high-quality fiberglass antenna and low-loss LMR400 cable, you remove the chokehold on your LoRaWAN gateway. You allow the high-sensitivity radio chip to do its job, ensuring your sensors stay connected even at the edge of the range.