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Projects, Kits & Hacks

Radio astronomy is one of the few sciences where an amateur can still gather real, publishable-quality data from the backyard. This page is a curated, link-verified field guide to the projects, kits, full systems, hacks, and parts suppliers that get you observing — from a salvaged satellite dish you wire up in an afternoon to a turnkey hydrogen-line observatory.

It pairs with the hands-on hardware chapters of the course — Chapter 5: Hands-on SDR and Chapter 6: Detecting the Hydrogen Line — and with the institutions and communities listed in Resources. For the underlying science, see the References.

New here? Start with one of these

  • NASA Radio JOVE — build a simple antenna and SDR receiver and hear Jupiter and the Sun at ~20 MHz. The classic on-ramp.
  • Itty Bitty Telescope — a salvaged satellite dish + signal meter that "sees" the warm Sun against the cold sky.
  • Cheap hydrogen line — a WiFi grid dish + a 1420 MHz LNA + an RTL-SDR detects the 21 cm line of galactic hydrogen for ~$200.

Prices and availability change constantly and are approximate (mid-2026). For RF parts — LNAs, filters, cables, connectors — prefer reputable vendors over unbranded marketplace clones, where noise figure and quality vary wildly.

Kits (you build it)

Buy a box of parts and a guide, assemble, observe.

  • NASA Radio JOVE (2.1) — The flagship education kit: an SDRplay RSP1B receiver, a build-it-yourself dual-dipole antenna, cabling, and Radio-Sky Spectrograph software. It listens over ~8 MHz around 20 MHz to capture Jupiter's decametric storms, solar radio bursts, and the Milky Way's galactic background. Beginner-to-intermediate. Radio JOVE kits · project home
  • Nooelec SAWbird+ H1 — A pocket-sized SAW filter + dual-LNA module centred on 1420 MHz: the essential front end for detecting the neutral-hydrogen (21 cm) line. Pair it with an RTL-SDR and an antenna and you can map galactic hydrogen; ~$45, beginner-friendly. nooelec.com
  • SARA "Scope in a Box" — A ready-made hydrogen-line starter kit refined by the Society of Amateur Radio Astronomers from an RTL-SDR design; parts drop-ship and you get instructions plus software. Observes the 21 cm HI line; ~$350 (US shipping). radio-astronomy.org
  • MIT Haystack Very Small Radio Telescope (VSRT) — A classroom interferometer from off-the-shelf parts; a compact-fluorescent-lamp "radio source" lets students explore propagation, polarisation, and interference. Under $500, build-from-plans, grades 8–12. Haystack VSRT

Full & turnkey systems

Mostly assembled, higher cost — for schools, universities, and serious hobbyists.

  • MIT Haystack Small Radio Telescope (SRT) — The classic undergraduate radio telescope: a ~2–3 m dish with a 1.4 GHz receiver for the Sun, the hydrogen line, and basic spectroscopy. The original commercial kit is retired; Haystack now publishes plans and open srt-py (Python + GNU Radio) software so institutions self-build. SRT for education · srt-py on GitHub
  • Radio2Space SPIDER 230C — Entry point to PrimaLuceLab's commercial line: a compact 1420 MHz hydrogen-line radio telescope with the H142-PRO receiver and RadioUniversePRO software. Turnkey but a serious instrument; ~$19,000. Radio2Space SPIDER
  • Radio2Space SPIDER 300A / 500A — 3 m and 5 m dishes with automatic tracking for universities, museums, and science institutes — enough to map galactic hydrogen and measure the Milky Way's rotation. Fully turnkey; ~\(49,000 / ~\)110,000. Radio2Space SPIDER

Homebrew & open-source builds

Telescopes you build largely from scratch, from published plans and open designs.

Online & open-source

  • PICTOR — A free-to-use online hydrogen-line observatory by Apostolos Spanakis-Misirlis: a 1.5 m dish in Athens (feedhorn + two-stage LNA + RTL-SDR + GNU Radio) that anyone can point and drift-scan through a web browser — no hardware required. The full open hardware/software design is on GitHub if you want to replicate it. pictortelescope.com · GitHub

Hydrogen-line (21 cm) horn antennas

  • DSPIRA "Sky's the Limit" horn telescope — The NSF-funded WVU project's flagship build: a pyramidal horn from lumber, foil-faced insulation board, and aluminium tape, paired with a ~$30 LNA, an RTL-SDR, and a GNU Radio spectrometer. Full lesson plans make it the go-to teaching design for the 1420 MHz line. DSPIRA lessons · build overview · open hardware (LNAs)
  • "Shoestring" DIY hydrogen-line telescope — A remarkably well-documented build by a high-school teacher and a former student: a foil-and-insulation pyramidal horn feeding a paint-can waveguide, an H-line LNA + filter, and an Airspy running GNU Radio. A great "how it's really done" reference. Hackaday writeup
  • Project H Line 3D — A beginner's guide using an easily fabricated 13-element Yagi (~15 dBi) plus LNA and RTL-SDR, with a full software workflow for drift-scanning and even 3D-graphing galactic hydrogen. An antenna-focused alternative to a horn. RTL-SDR overview
  • BHARAT (Bose Horn Antenna Radio Telescope) — A peer-reviewed (American Journal of Physics) teaching design from IUCAA, India: an efficient, low-cost dual-mode conical horn for 21 cm experiments, used in university lab curricula. More rigorous than the hobbyist horns, and openly published. arXiv:2208.06070

Advanced: pulsars & interferometry

  • Amateur pulsar detection of B0329+54 — A milestone homebrew result by Job Geheniau: detection of the bright pulsar PSR B0329+54 with a 1.9 m dish + RTL-SDR (software help from Michiel Klaassen), reportedly a first at that dish size. A concrete target for dish + SDR owners. RTL-SDR coverage
  • Home-built radio interferometer — NRAO's "Ask an Astronomer" confirms a rudimentary two-antenna interferometer is buildable at home and points to worked amateur examples and interferometry theory — the most advanced rung of the homebrew ladder. NRAO: home-built interferometer

Hacks & afternoon experiments

Clever, cheap, repurposing-based observations — many doable in an afternoon. Cost levels assume you already own a computer.

Sun & sky with a satellite dish

  • Itty Bitty Radio Telescope (IBT) — Bolt a satellite-finder signal meter onto a discarded TV dish + LNB and sweep the sky: warm objects (trees, buildings, your hand) glow against the cold sky, and you'll pick up the Sun at ~12 GHz. The classic near-zero-cost beginner build. NRAO IBT · build guide
  • 11.2 GHz dish radio telescope — A step up: a 1.2 m prime-focus TV dish with a Ku-band LNB feeds an SDR (the LNB down-converts ~11 GHz to ~1.4 GHz). Good enough for solar and lunar transits and Galactic-plane drift scans. RTL-SDR.com build

Hydrogen line & passive radar with an RTL-SDR

  • Hydrogen line in an afternoon (~$200) — A 2.4 GHz WiFi parabolic grid dish + a 1420 MHz LNA + an RTL-SDR Blog dongle, with SDR# and the IF-Average plugin, detects the 21 cm line and even the Doppler shift of the spinning Galactic plane. The canonical cheap radio telescope. RTL-SDR.com tutorial
  • Passive radar / aircraft scatter — Two RTL-SDR dongles on a shared clock turn a local FM tower into a passive radar that detects aircraft from reflected signals; a single-dongle version watches a VOR beacon for Doppler-shifted echoes. FM passive radar · VOR aircraft scatter

Meteors

  • GRAVES meteor scatter (Europe) — Tune an RTL-SDR just below the 143.050 MHz GRAVES radar in France, aim a small VHF antenna skyward, and watch brief "pings" as the radar reflects off ionised meteor trails. Cheap and beginner-friendly across much of Europe. RTL-SDR.com: GRAVES meteors
  • FM/VHF meteor pings (worldwide) — No GRAVES nearby? Tune a VHF receiver to a vacant ~88 MHz frequency and point a directional antenna up; distant transmitters reflected off meteor trails appear as short bursts. BAA: Meteor Reflections

VLF & the ionosphere

  • INSPIRE / natural-radio listening — A simple VLF receiver lets you hear the magnetosphere: sferics (lightning pops), tweeks, and whistlers (descending tones guided along Earth's field lines). A great no-licence entry hack, best away from mains hum. The INSPIRE Project
  • SuperSID / SID monitor — A small pre-amp and a ~1 m loop antenna feed a sound card to watch distant VLF transmitters; when a solar flare hits, the sudden ionospheric disturbance shifts the signal and you've detected the flare. Inexpensive, runs indoors 24/7. Stanford SOLAR Center · SARA SuperSID kit

Lightning & sferics

Lightning is the loudest natural radio source you can hear from the backyard: every return stroke radiates a broadband impulse that peaks in the VLF band (~5–10 kHz) and reaches up into VHF. Those impulses — sferics — bounce around the Earth–ionosphere waveguide as tweeks and, when they leak up a geomagnetic field line and disperse, return as whistling whistlers. The physics is the same plasma dispersion you meet with pulsars and FRBs (a whistler's group delay goes as \(t \propto f^{-1/2}\), the close cousin of the interstellar \(t \propto \nu^{-2}\)), and lightning is also a textbook broadband RFI source that radio observatories must flag — so these builds tie straight back to Chapter 13 (Pulsars), Chapter 18 (FRBs), Chapter 27 (VLF & the Ionosphere), and Chapter 39 (RFI Mitigation). The same techniques even detect lightning on other planets — Saturn's electrostatic discharges and Jupiter's whistlers were found by Voyager, Cassini, and Juno.

  • Join Blitzortung / LightningMaps (citizen-science geolocation) — The most rewarding build: a small VLF loop/ferrite antenna and a GPS-timestamped controller board upload sferic arrival times to a global server, which trilaterates each strike by time-of-arrival (the same hyperbolic geometry as VLBI in Chapter 19). Hundreds of stations feed the live map; kits are ~$50–200 and the data are free to use. How to cover your area · live map · WWLLN (the academic network)
  • AS3935 "Franklin" lightning sensor — A single I²C/SPI chip with a 500 kHz resonant front end and an on-board classifier that flags strikes vs man-made "disturbers" and estimates distance (1–40 km). Cheap (~$25) and Raspberry-Pi/Arduino-friendly — great for a "storm is approaching" alarm, though it's single-station (no direction or geolocation) and its 500 kHz band misses the VLF energy peak. SparkFun hookup guide · ScioSense AS3935
  • Soundcard / RTL-SDR sferic & whistler receiver — Because VLF lightning emission lands in the audio band, a loop antenna + high-gain pre-amp + a 96 kHz sound card records raw sferics, tweeks, and whistlers with no down-conversion — point a spectrogram at it and the descending whistler tones appear directly. (An RTL-SDR with an upconverter, or HF direct-sampling, catches the "crashes" higher up the band.) The open-source vlfrx-tools toolkit adds GPS-locked timing and sferic analysis; the INSPIRE Project (already above) is the classic listen-first on-ramp.

Sources for radio-astronomy parts

Where to buy the components for the projects above.

Software-defined radios (SDRs)

  • RTL-SDR Blog — The reference budget dongle (Blog V4); also sells the radio-astronomy Discovery Dish. Best starting point for hydrogen-line work. rtl-sdr.com store
  • Nooelec — NESDR family of RTL-SDR dongles, including bias-tee "SMArTee" models that power an LNA over coax. nooelec.com
  • Airspy — Higher-dynamic-range receivers (R2, HF+ Discovery) when 8-bit isn't enough. airspy.com
  • SDRplay — RSP series (RSP1B, RSPdx, RSPduo) with 14-bit ADCs and free software. sdrplay.com
  • HackRF (Great Scott Gadgets) — Open-source 1 MHz–6 GHz transmit/receive SDR. greatscottgadgets.com
  • Ettus Research / USRP — High-end, calibrated USRP platforms for instrumentation budgets. ettus.com
  • KrakenSDR — Five RTL-SDR receivers on one board sharing a single clock, phase-coherent by design — the affordable on-ramp to amateur interferometry and direction finding (a stock RTL-SDR has no external clock input, which is what makes coherent multi-receiver work hard; see Field Notes). ~$450. krakenrf.com

Low-noise amplifiers (LNAs) & filters

  • Nooelec — SAWbird+ H1 (1420 MHz SAW filter + cascaded LNA, purpose-built for the hydrogen line) and the wideband LaNA. SAWbird+ H1 · LaNA
  • RTL-SDR Blog — Wideband bias-tee LNA (50 MHz–4 GHz, <1 dB NF) plus band-stop/high-pass filters. rtl-sdr.com store
  • Mini-Circuits — Lab-grade connectorised LNAs (ZX60 series), bias tees, attenuators, and filters; the professional choice. minicircuits.com
  • LNA4ALL — Popular DIY-favourite wideband LNA (PSA4-5043+, ~0.75 dB NF). lna4all.blogspot.com
  • Mini-Kits (AU) — Low-noise amplifier and preamp kits/modules for HF–microwave. minikits.com.au

Antennas, feeds, horns & dishes

  • RTL-SDR Blog Discovery Dish — Near off-the-shelf lightweight dish + 1420 MHz feed (integrated LNA/filter) for hydrogen-line and L-band reception. rtl-sdr.com store
  • WiFi grid antennas (2.4 GHz parabolic grids) — Cheap ~1 m grid dishes repurposed with a 1.4 GHz feed are a classic budget hydrogen-line telescope; sold by networking retailers and surplus channels.
  • Surplus satellite dishes — Offset Ku-band TV dishes and old C-band dishes make good reflectors; source from classifieds, ham swaps, and university surplus (see below).
  • DIY horns & cantennas — Pyramidal horn / waveguide-can feeds from sheet metal, paint cans, or foil board. Build references: Lichfield RAO horn guide · PhysicsOpenLab.
  • Pasternack — Commercial waveguide-to-coax adapters and feed hardware. pasternack.com

Connectors, cable & RF bits

  • Digi-Key · Mouser · Newark/element14 — The three major distributors: SMA/N/F connectors, adapters, attenuators, bias tees, and coax, in stock with fast shipping. digikey.com · mouser.com · newark.com
  • Pasternack — RF specialist: connectors, adapters, attenuators, jumper cables, off the shelf. pasternack.com
  • L-com — Pre-made LMR-400 and low-loss coax jumper assemblies plus bulk cable. l-com.com
  • Amphenol RF — Connector manufacturer (SMA, N, F, MCX…); buy through the distributors above. amphenolrf.com

Surplus, generic & maker sources

  • Adafruit · SparkFun — Maker-friendly sources for the HackRF, RTL-SDR kits, and general electronics. adafruit.com · sparkfun.com
  • eBay · AliExpress · Amazon — Surplus dishes, LNAs, connectors, and dongles, often cheap. Caution: many unbranded RF parts are clones with poor or unspecified noise figure — verify the seller and specs, and prefer genuine branded gear for the front end. ebay.com · aliexpress.com · amazon.com
  • University surplus & ham-radio swap meets — Excellent for free/cheap dishes, coax, connectors, and test gear. Check local hamfests and your nearest university's surplus sales.

Documented amateur builds (worked examples)

Full write-ups — schematics, antenna dimensions, photos, and results — from SARA members, useful as reproducible blueprints rather than just kit listings:

Communities & going further

You don't have to go it alone — amateur radio astronomy is small, friendly, and open.

  • Society of Amateur Radio Astronomers (SARA) — The hub: projects, the bi-monthly Radio Astronomy journal (since 1981; public article index), six special-interest sections, and a Getting Started guide tying together Radio JOVE, SuperSID, INSPIRE, the IBT, and meteor work. Student membership is ~$5/yr. radio-astronomy.org
  • **SARA grants for students & teachers (~\(200)** — SARA funds hands-on projects — observing Jupiter/the Sun, VLF/SID and solar-flare detection, building portable telescopes — up to ~\)200 for anyone from 5th grade through college, and for teachers: a ready way to fund a first build. grants
  • SARA community channels — a public Google Group (SARA membership not required to read or join), two monthly Zoom meet-ups (the live "Observation Party" and the open-forum "Drake's Lounge"), and annual conferences at Green Bank and Socorro (online attendance ~$25). meetings
  • GAVRT — operate a real NASA antenna (no hardware needed) — the NASA/JPL + Lewis Center Goldstone-Apple Valley Radio Telescope program lets students remotely run a 34 m Deep Space Network dish over the web on guided campaigns: Jupiter Quest (Jupiter's GHz synchrotron radiation belts, compared with Juno), Black Hole Patrol, and Solar Patrol. Free after a short online training — the no-build route to research-grade data on a real instrument. gavrt.lewiscenter.org · NASA program
  • British Astronomical Association — Radio Astronomy Group — Active UK community with beginner guides and projects. britastro.org
  • Open Source Radio Telescopes — A community catalogue of open, reproducible builds. opensourceradiotelescopes.org
  • Cloudy Nights — scientific/amateur astronomy forum — A large, friendly community whose scientific subforum is an active place to ask radio-astronomy questions. cloudynights.com
  • SatNOGS — A global network of open-source satellite ground stations; a great way to put an SDR + antenna to collaborative use. satnogs.org
  • saveitforparts (YouTube) — Entertaining, instructive builds of radio telescopes and satellite receivers from salvaged parts. youtube.com/@saveitforparts

Where your observations can go

Several builds above feed live citizen-science networks where you can submit and compare your own data: VLF/solar-flare traces to the Stanford SuperSID network and the AAVSO SID program; meteor counts to the American Meteor Society; Jupiter/solar recordings to the Radio JOVE archive; and lightning sferics to Blitzortung / LightningMaps.

You can always just listen

Radio astronomy is receive-only — no licence required. (A licence is only for transmitting.) Before buying anything, you can even tune real receivers over the web with WebSDR or KiwiSDR.

For more hard-won practical advice from the amateur community — what's actually discoverable, the hardware gotchas, why interferometry is hard, and the RFI traps — see Field Notes from the Community.

For observatories, archives, university groups, and journals, see Resources; for the foundational papers behind these experiments, see the References.