How an inductor works
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An inductor is one of the simplest components in electronics, but its behaviour comes from a deep physical effect: a current creates a magnetic field, and changing that current induces…
Radio Astronomy
How resonant radio frequency circuits work
How Resonant RF Circuits Work: Resonant RF (radio-frequency) circuits—also called LC resonant or tuned circuits—use an inductor (L) and a capacitor (C) to create a natural oscillation at a specific…
How does the radio frequency SAW filter in a Nooelec SAWBird LNA and filter?
In the SAWBird line of LNAs (e.g., for 1420 MHz, GPS, L-band), the SAW filter is the component that provides the ultra-narrow preselection that makes these modules so effective for…
What is spillover vs ground reflection in radio astronomy?
In a radio telescope’s noise budget, spillover and ground reflection are two distinct ways unwanted radiation enters your receiver. They’re related but not the same: Spillover Spillover is receiver noise…
What difference does choice of material make with regards to construction of antennas?
Material choice affects an antenna’s efficiency, bandwidth, durability, and mechanical practicality. Here’s a concise breakdown of what really matters: 1. Electrical Conductivity This is the biggest factor. High-conductivity metals (copper,…
Is it benefitial to ensure that low noise amplifier and filter (LNA) for hydrogen line observing is at a constant temperature?
Andrew Thornett: I could see potential benefit for having LNA at constant temperature. The easiest way to achieve that is to cool it below any likely outside temperature – avoiding…
What is most expensive low noise amplifier and/or filter available for hydrogen line radio astronomy?
Short answer: the most expensive single-component front-end parts used for 1.420 GHz (H-line) work are cryogenic HEMT/InP LNAs and the associated cryogenic front-end systems (LNA + cryostat + cryocooler). Top…
Pulsars don’t have a single “pulsar frequency” the way spectral lines do.
Pulsars don’t have a single “pulsar frequency” the way spectral lines do — instead they emit broadband radio noise with periodic pulses, and what we observe are: Here are the…
Description of SAWBird H1+ LNA from Nooelec’s own website 23/11/2025
This might be of interest to folks interested in amateur hydrogen line radio astronomy – it is the description of the SAWBird H1 directly from Nooelec’s website today 23/11/2025: https://www.nooelec.com/store/sawbird-h1.html…
What’s Different Between different Nooelec versions of the RTL-SDR device?
There are quite a few different Nooelec RTL-SDR dongle versions, and the differences mostly come down to tuner chip, frequency range, stability / oscillator, size, and extra features like bias-tee.…