High School / HS-14
Available Grades 9–12 RF & space Computing & data
Build a small 1420 MHz receiver with a horn antenna and SDR, try to detect 21-cm hydrogen emission from the Milky Way, and turn its Doppler shift into a velocity.
Students build a receive-only horn radio telescope (foam-board pyramidal horn after Patel et al., plywood waveguide feed, SAWbird+ H1 LNA, RTL-SDR), detect 21 cm emission from neutral hydrogen at 1420.405 MHz, correct its Doppler shift to the Local Standard of Rest, and use the tangent-point method to measure the Milky Way's rotation curve and enclosed mass.
Students will:
Every high school pack includes worked math and physics, prediction-versus-measurement labs, at least two design-and-test iterations, data logging, a rubric, and documentation templates, plus printable Builder's Corner build journal pages.
Parts, specs, quantities, and estimated unit costs, with places to buy. Prices change; anything marked as an estimate is an estimate. Links were checked when the BOM was written.
Totals are computed from the line items below. Prices were read from vendor pages on the dates shown and will change. Rows tagged estimate have no verified link and are planning numbers only.
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| E1 | RTL-SDR Blog V3 SDR (dongle only) RTL2832U + R820T2/R860 tuner, 1 PPM TCXO, SMA; software-switched 4.5 V bias tee (V3/V4 user guide: up to 180 mA continuous). Receive-only hardware. | 1 | $39.95 | $39.95 | rtl-sdr.com RTL-SDR Blog store $34.95 – $39.95 USD (Dongle Only listing) · checked 2026-10-09 · Page: Amazon USA and Chinese warehouses in stock | RTL-SDR Blog V4L (Lite), $37.95 dongle only, same page; newer, page warns some software lags in support. Airspy Mini/R2 (DSPIRA's choice, more bandwidth, more cost). V3 also listed with a USB-C connector at the same price. | Bias tee OFF by default (see safety.md § 2) |
| E2 | Nooelec SAWbird+ H1 hydrogen-line LNA + SAW filter Page: 2 cascaded LNAs around a SAW filter centred near 1.42 GHz, 65 MHz passband, ≥ 40 dB gain, NF ≈ 0.8 dB, nominal current 120 mA; power via SMA output (bias tee, 3–5 V) OR micro-USB OR header, ONE at a time | 1 | $49.95 | $49.95 | nooelec.com Nooelec $49.95 · checked 2026-10-09 · Not shown on page | DSPIRA LNA (solder-yourself PCB) or a filtered 1420 MHz LNA (both listed on the DSPIRA horn page; not price-checked here) | 120 mA is inside Dr. Haney's ≈ 125 mA bias-tee limit with little margin: nothing else on that line |
| E3 | SMA male–SMA male pigtail, RG-316, 0.5 ft Nooelec · probe connector → LNA, and LNA (or DC block) → SDR | 2 | $8.95 | $17.90 | nooelec.com Nooelec $8.95 · checked 2026-10-09 · Not shown on page | RTL-SDR Blog SMA adapter sets on the store page | — |
| E4 | SMA in-line DC block Nooelec SKU 100816 · 50 kHz – 8 GHz, 50 Ω, 2 W. REQUIRED with the default separate LNA power (Option B) | 1 | $24.95 | $24.95 | nooelec.com Nooelec US$24.95 · checked 2026-10-09 · Not shown on page | Mini-Circuits BLK-89-S+ (page fetched, price not shown without login) | Low total assumes the bias-tee fallback (Option A) with no DC block |
| E5 | SMA female bulkhead, 4-hole flange, solder cup Probe feed-through in the waveguide; centre hole 6.5 mm, screw holes 2.7 mm on 8.6 mm square in sheet-1 (check your part) | 1 | $4.00 estimate | $4.00 | Electronics retailer (no link) — | Panel-mount SMA with nut (single 6.5 mm hole; ignore the 4 small holes) | Adult solders the probe |
| E6 | Solid copper wire 12 AWG (≈ 2 mm), 10 cm Quarter-wave probe, trimmed to 53 mm above the wall (Patel et al.) | 1 | $1.00 estimate | $1.00 | Hardware store (no link) — | Brass rod 2 mm | — |
| E7 | USB 2.0 extension cable, 3 m SDR rides on the horn; laptop stays on the table | 1 | $8.00 estimate | $8.00 | Retail (no link) — | Classroom stock | Route cables so nobody trips |
| E8 | USB power bank + micro-USB cable (Option B, default) Powers the SAWbird separately; then bias tee OFF and DC block E4 in line | 1 | $0.00 estimate | $0.00 | Classroom stock (no link) — | Default power; not needed only for the Option A fallback | — |
| Subtotal | $145.75 | Low-cost path: $105.80 | |||||
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| S1 | Foil-faced polyiso foam board, 1/2 in, 4 × 8 ft Four horn panels (templates horn-broad-panel.svg, horn-narrow-panel.svg; panels ≈ 0.79 × 0.74 m and 0.61 × 0.75 m) | 1 | $22.00 estimate | $22.00 | Home improvement store (no link) — | Cardboard + kitchen aluminum foil (Patel et al. built one this way) | Adult cuts with a utility knife (§ 4) |
| S2 | Aluminum foil tape, 2 in roll Lines the plywood waveguide and seals horn seams (conductive inside surface) | 1 | $10.00 estimate | $10.00 | Hardware store (no link) — | — | Tape edges are sharp: peel slowly |
| S3 | Baltic birch plywood 3 mm, 12 × 20 in Wood Vault, 1/8" Laser/CNC grade variant; 4 sheets (sheet-1, sheet-2, sheet-3; sheet-3 holds 2 cheeks + 4 clamps; cheeks and clamps are laminated pairs) | 4 | $3.50 | $14.00 | woodvault.com The Wood Vault $3.50 per sheet (1/8" Laser/CNC grade variant) · checked 2026-10-09 · Not confirmed (variant page) | Any 3 mm laser plywood | Trained adult runs the laser cutter |
| S4 | Bolts: 2 × 1/4-20 × 1-1/2 in + 2 nylon-insert lock nuts + 24 × 1/4 in flat washers (pivots, 13–14 mm spacer each side); 2 × M4 × 40 + nuts (elevation pins); clamp standoffs 2 × M4 × 80 + 2 × M4 × 100 + 12 M4 nuts + 8 fender washers (≤ 25 mm OD) + 8 M4 washers Stand hardware | 1 | $16.00 estimate | $16.00 | Hardware store (no link) — | — | — |
| S5 | Wood glue, hot-glue sticks, 2×4 base ≈ 630 mm (horn outside width at the balance point + 2 × 40 mm cheek, spacer and standoff room + 2 × 30 mm; measure); ≥ 20 kg sandbag ballast + straps (school stock) Laminate cheeks; glue foam seams before taping | 1 | $6.00 estimate | $6.00 | School stock (no link) — | — | Hot glue: low-temp gun |
| S6 | Laser cutter access or cutting service 3 sheet designs, 4 sheets (estimate) | 1 | $10.00 estimate | $10.00 | Makerspace / cut service (no link) — | — | Trained adult operates the laser cutter |
| Subtotal | $78.00 | Low-cost path: $56.00 | |||||
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| T1 | Temperature-controlled soldering iron Pinecil · probe to SMA solder cup | 1 | $68.50 | $68.50 | sparkfun.com SparkFun $68.50 · checked 2026-10-09 · Not recorded | Assumed owned in the low total | Adult solders (heavy wire needs heat) |
| T2 | Lead-free solder 15 g SparkFun | 1 | $4.95 | $4.95 | sparkfun.com SparkFun $4.95 (single-unit price) · checked 2026-10-09 · Not recorded | — | Wash hands after soldering |
| T3 | Safety glasses, ANSI Z87.1 (Z87+) impact-rated, clear 3M SecureFit SF201AF · clear anti-fog polycarbonate lens marked Z87+ (ANSI Z87.1 impact-rated; 3M spec table on strobelssupply.com and safetycompany.com, read 2026-10-09); soldering, wire trimming, laser cutting, foam cutting | 2 | $5.32 | $10.64 | platt.com Platt Electric Supply $5.32 EA · checked 2026-10-09 · 40 in stock (company-wide) | Any glasses marked Z87+ (ANSI Z87.1 high-impact). Not SparkFun SWG-11046: it lists only CE/EN 1836, a sunglass standard, not impact-rated | Check the Z87+ marking on arrival |
| T4 | Utility knife with snap-off blades, metal straightedge, cut-resistant gloves Foam-board panels (adult cuts; students mark and tape) | 1 | $25.00 estimate | $25.00 | Hardware store (no link) — | Assumed owned in the low total | Adult only; cut away from the body, on a cutting mat |
| T5 | Laptop with Python 3 + numpy (+ matplotlib, pyrtlsdr) and the RTL-SDR driver hline.py capture / reduce / rotation; GNU Radio optional | 1 | $0.00 estimate | $0.00 | School (no link) — | — | — |
| T6 | Digital multimeter Continuity (probe is NOT shorted to the wall) and DC check on the coax | 1 | $20.00 estimate | $20.00 | Retail (no link) — | Assumed owned | — |
| Subtotal | $129.09 | Low-cost path: $15.59 | |||||
The pack is digital files only. Hardware is bought separately.
These are standards the pack's activities are mapped to by Laue Labs. They are not a certification or endorsement by any standards body or state.
"Mapped to" means Laue Labs' alignment, not a certification.
| Activity | NGSS HS performance expectations | Practices / crosscutting | Common Core HS math |
|---|---|---|---|
| Lab 1 Doppler & frames | HS-PS4-1 (wave frequency, wavelength, speed); HS-ESS1-2 (evidence for the Big Bang uses Doppler/spectra: same method) | Using mathematics; Scale, proportion | HSN-Q.A.1–3 (units), HSA-CED.A.4 |
| Lab 2 feed, horn, Sun scan | HS-PS4-5 (devices that use waves to capture information); HS-ESS1-4 (motion in the solar system: Earth's rotation) | Developing and using models; Planning investigations | HSG-SRT.C.8 (trig), HSF-TF.A |
| Lab 3 T_sys, radiometer | HS-PS4-2 (digital vs analog signals, noise); HS-ETS1-3 (trade-offs) | Analyzing data; Stability and change | HSF-LE.A (power laws via logs), HSS-ID.B.6 |
| Lab 4 first light | HS-ESS1-1 / HS-PS4-3 (electromagnetic radiation; particle/wave models of light) | Obtaining evidence; Patterns | HSN-VM.A (vectors: LSR projection) |
| Lab 5 rotation curve | HS-PS2-4 (Newton's law of gravitation), HS-ESS1-4 (orbits) | Engaging in argument from evidence; Systems and system models | HSF-IF.B.4, HSS-ID.B.6 |
| Build | HS-ETS1-2 (break a complex problem into smaller problems), HS-ETS1-3 | Constructing explanations and designing solutions | HSG-MG.A.3 (design with geometry) |
One student or one household.
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One homeschool family, or one co-op group of up to 10 learners with its facilitator(s).
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One teacher with up to 30 students in a single class or cohort.
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All licenses: digital files only (hardware not included). Keep Laue Labs attribution on printed handouts. After checkout you get an instant download on the thanks page. License questions, more learners, or site licenses: lance.haney@gmail.com.
