If you've ever run a long stretch of coax between your antenna and your receiver, you've probably noticed your signal gets weaker along the way — sometimes enough to bury a weak station in noise before it even reaches your radio. A remote LNA solves this by putting the amplifier where it actually matters: right at the antenna, not back at your desk.
This article covers what a remote LNA is, why placement matters more than most people expect, and how to power one using a bias tee — including the difference between two very similar-looking amplifiers that actually solve different problems.
What Is a Remote LNA?
A remote LNA (low noise amplifier) is an amplifier placed at or near the antenna, rather than at the receiver, to boost a weak signal before it travels down a long run of coax. Powering it at a distant location — often outdoors, at the top of a mast, or simply across a room from your SDR — is the "remote" part, and it's almost always done using a bias tee, which sends DC power up the same coax cable that carries the RF signal back down.
Why Placement Matters More Than You'd Think
This is worth understanding before you buy anything, because it explains why "remote" isn't just a convenience feature — it's the whole point. Every foot of coax between your antenna and the first amplifier adds loss, and that loss adds directly to your system's noise figure. In practice, this means a weak signal that's already struggling loses even more ground before anything has a chance to boost it. Amplifying it after a long, lossy cable run means you're amplifying a signal that's already been degraded — you can make it louder, but you can't undo the noise the cable already added.
Put the amplifier at the antenna instead, and it boosts the signal before the cable run, so the cable's loss becomes far less consequential to your overall noise performance. This is the entire reason remote LNAs exist as a category, rather than everyone just using an amplifier at the receiver end.
Want to see exactly how much this matters for your own setup? Our LNA Placement Calculator uses your actual cable loss and LNA specs to show the real noise figure difference between the two placements.
How a Remote LNA Gets Power
Since the amplifier is out at the antenna — often somewhere without a convenient power outlet — it needs power delivered through the same cable that's already running back to your receiver. That's a bias tee's job: combining DC power and RF signal onto a single coax line, so the LNA can be powered from your SDR, radio, or a separate supply without running a second cable. (We cover exactly how a bias tee circuit works, down to the component level, in our companion article: What Is a Bias Tee Circuit?
Most SDRs with a built-in bias tee — RTL-SDR, HackRF, SDRplay — can power a remote LNA directly, though it's worth checking your specific device's bias tee voltage and current rating against the LNA's requirements before assuming compatibility.
The Distinction That Actually Matters: Output-Only vs. Input-and-Output Bias Tee
This is where two very similar-looking remote LNAs can solve genuinely different problems, and it's worth understanding before you buy.
An output-only bias tee LNA receives DC power from your receiver's bias tee, uses it to run the amplifier, and passes the amplified RF signal on. That's it. Power flows in one direction: from your receiver, into the LNA. This is the right tool when the LNA itself is the only thing that needs power — for example, when it's connected to a plain, passive antenna.
An input-and-output bias tee LNA does everything the output-only version does, but also passes DC power further upstream — out through its input connector — to power something else even further out in the chain, like an active antenna's built-in amplifier, or a second LNA mounted even closer to the antenna. This is the right tool when you have more than one thing that needs power, arranged in a chain, not just the LNA itself.
The deciding question is simple: does anything upstream of this LNA also need power? If you're feeding it from a passive antenna, an output-only bias tee LNA is not just sufficient, it's the safer choice. If you're feeding it from an active antenna, you need the input-and-output version to actually deliver power to that antenna's amplifier.
A Real Safety Consideration Worth Knowing
If you use an input-and-output bias tee LNA with a passive antenna instead of an active one, DC voltage still appears at the RF input, since that's how the LNA passes power upstream. Most passive antennas simply don't use that DC — but some antenna designs (particularly those with an intentional DC path to ground, sometimes included for static or lightning protection) present a low-impedance or shorted path at DC. In that case, the bias tee's power supply is effectively driving into a short.
With a properly current-limited power source, this is usually a non-event — the supply just limits current and nothing is damaged. With an unprotected supply, it's worth avoiding. If you're not sure whether your passive antenna presents a DC short, an output-only bias tee LNA sidesteps the question entirely, since it never applies DC to its input.
GPIO Labs Remote LNAs Compared
Both of these share the same core amplifier design, and once you look past the bias tee configuration, they're nearly identical: same 10 MHz–3000 MHz frequency range, same 0.7 dB noise figure, same +30 dBm output IP3 at 2 GHz, same roughly 20 dB peak gain, same ESD protection diode at the input. There's really only one functional question that separates them, plus a small price difference:
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Output Bias Tee LNA DC power comes in from your receiver's bias tee and stays there — nothing is passed upstream. The right choice for a passive antenna, or when this LNA is the only thing in the chain that needs power.
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Inline Amplifier, Input + Output Bias Tee Does everything the version above does, but also passes DC power upstream through its input connector — to an active antenna's built-in amplifier, or a second LNA further out in the chain. The right choice whenever something beyond this LNA also needs power.
If you're not sure which one you need: the deciding question is simple — does anything upstream of this LNA also need power? If yes, get the input-and-output version. If no, the output-only version does the same job for less.
Need help matching a remote LNA to your specific antenna and receiver setup? Contact us — we're happy to help you figure out which configuration fits your application.