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GPIO LABS · RF TOOLS Placing an LNA at the antenna instead of the receiver typically improves system noise figure by several dB, because cable loss affects the signal far less after amplification than before it. Enter your cable loss and LNA specs below to see the exact difference for your setup. Cable loss (dB) Total loss for your full cable run LNA noise figure (dB) Default matches our remote LNAs LNA gain (dB) Default matches our remote LNAs — better system noise figure with the LNA at the antenna LNA at the Antenna Amplify first, then the cable run...

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...

GPIO LABS · RF TOOLS A bias tee's inductor and capacitor need reactance values set well apart from your system impedance to work correctly — but a single L/C pair only covers a limited frequency range before the inductor's self-resonant frequency (SRF) causes it to fail. Enter your frequency range and impedance below to size both components and check whether a single pair will actually work for your design. Minimum frequency (MHz) Maximum frequency (MHz) Set equal to the minimum for a single-frequency (narrowband) design System impedance 50 Ω 75 Ω Reactance margin 5× (tighter) 10× (safer) MIN INDUCTANCE (L)...

If you've ever set up a GPS receiver, an SDR, or an ADS-B antenna and run into this problem — your active antenna needs power, but you don't want to run a separate power cable all the way up to it — a bias tee is the part that solves it. It lets you send DC power to a remote antenna or inline amplifier through the exact same coax cable that's already carrying your RF signal.     This article covers what a bias tee actually does, how the circuit works, and how to pick the right one for your...

Most SDR users deal with occasional FM broadcast interference. Ethan deals with 23 FM radio stations, all transmitting from the same antenna on a 328-metre tower a few kilometres from his front door. Auckland's Sky Tower is home to the world's largest FM combiner, and living in its shadow means every wideband receiver picks up FM energy strong enough to consume its entire dynamic range. A GPIO Labs FM Notch Filter permanently installed ahead of each SDR was the fix. He also found it worked on a handheld radio with the same problem.