Outdoor Test Range Site, RSI Corp
- skylarkcolo
- May 28
- 3 min read
Updated: 10 hours ago
The RSI Corp antenna test range (also known as the K0UO Antenna Test Facility, "Antenna University," or K0UO Rhombic Farm/ATF) is a large-scale outdoor far-field antenna testing and development site integrated with 4KS Walz Airport in Kiowa, Kansas.
It is operated by Steven E. "Steve" Walz (ham radio callsign K0UO), who founded and directs RSI Corporation (full name: Radiofrequency Safety International), an Environmental Health & Safety (EH&S) firm specializing in RF/electromagnetic energy (EME) compliance at RF, AI data, NOC, and general work sites by conducting surveys, EHS, and training. The range leverages the airport's long open spaces and the surrounding rural, electromagnetically quiet 1,200+ acres of prairie/farmland in the Gypsum Hills area for real-world, anechoic-chamber-free testing.
Location and Airport Integration
4KS Walz Airport is a public-use, privately owned turf-strip airport about 4 miles northwest of Kiowa, KS (FAA identifier 4KS; coordinates approx. 37°02'43"N 098°34'13"W; elevation 1,387 ft). Steve Walz is the owner/operator.
Runway 3/21 is 2,525 ft × 50 ft (usable ~2,900–3,000 ft with displaced thresholds marked by cones). It has low-intensity edge lights, wind socks, and typical rural obstructions (trees, fences, oil wells/pumps, silos, and a prominent 195-ft tower—FCC ASR #1216715—near midfield ~375 ft east of centerline).
The antenna test range runs parallel to the runway, providing over 2,500 ft of clear far-field distance (Fraunhofer zone) plus access to 1,000+ acres for extended measurements. Portable towers, drones, and tie-down pads on concrete north of the hangar support setup. The airport sees general aviation (Cessna, etc.), short-field training, and beginning mid-2025: DoD/ISR contractor use, including test aircraft with electro-optical/infrared sensors, tactical radios, and data links.
Facilities and Capabilities
The site features the world's largest amateur (ham) high-frequency (HF) wire antenna installations by land area, tower count/height, and antenna quantity/gain, still being used today.
Rhombic arrays (re-entrant designs for ~90%+ efficiency and high forward gain, no terminating-resistor power loss), V-beams, curtain arrays, stacked LPDA-Yagis, four-square phased verticals, Beverages (receive), and more—covering 160 m to 2 m bands with optimized takeoff angles.
Support structures: Towers/poles 50–195+ ft (wood, Rohn, etc.), concrete silos, oil-well infrastructure repurposed.
Testing setup: NEC5/HFTA modeling first, followed by real far-field measurements (IEEE/MIL-STD protocols). Equipment includes calibrated Wandel & Goltermann EMR meters (E/H fields), spectrum analyzers, vector network analyzers, drones for 3D heat-map/pattern flights, portable crank-up towers, GPS/laser surveying, soil resistivity (Wenner 4-point method), and real-time data systems.
Measurements cover: Gain, radiation patterns (azimuth/elevation), beamwidth, front-to-back ratio, side lobes, impedance, ground loss/reflections, and regulatory compliance. Repeatability checks (5+ runs, RMS uncertainty) ensure precision for DOD, ham contesting/DX, commercial wireless, broadcast, and hyperscale AI data-center/MOC applications.
It is electromagnetically quiet with excellent soil for ground planes, making it ideal for precise, repeatable results without indoor chamber limitations.
Connection to RSI Corp and Broader Use
RSI Corp (headquartered at 543 Main St., Kiowa, KS; est. 1997 post-Telecom Act of 1996) focuses on RF safety: MPE assessments, hazard reports, OSHA/FCC/EPA/FAA compliance for (Verizon, AT&T, T-Mobile), DOD, Google, UPS, NOC and AI data centers. The K0UO range doubles as RSI's controlled antenna and RF/EMP/EMI safety test range for hands-on training. Test range location https://maps.app.goo.gl/cEKCoMn5f5YHsCDy5
Superior Survey Techniques™ (SST) course: A 2-day professional certification ($2,995) with classroom + practical surveys on Day 2 using site equipment/instruments. Targets RF safety pros; annual renewal required.
STEM/"Antenna University" role: Outdoor real-world lab for university aerospace/antenna research, high-school aviation (via KDOT), and ARDC programs. Invites groups for projects; AI tools aid analysis.
Military/DoD tie-ins: Supports ISR testing, special training ops at 4KS (e.g., SkyRaider II OA-1K, T-6/T-7A training under nearby MOAs), and EH&S for defense sites.
AI for Drone‑Based RF Pattern Measurement
The RSI/K0UO antenna test range uses drones to map far‑field patterns.
AI is used for:
Noise filtering
Pattern reconstruction
Data smoothing
Comparing measured vs. modeled patterns
Tools in this category include:
Computer‑vision ML models
RF‑pattern regression models
AI‑based anomaly detection
This is standard in modern RF test ranges.
Additional Context
The site emphasizes the scientific method: model → build → far-field test → refine. It is FAA-registered and supports day-to-dark ops (non-standard lighting). For visits, STEM inquiries, or testing: see k0uo.com (detailed blog posts on rhombics, ground, testing) or rsicorp.com; contact via k0uo@arrl.net or RSI at (620) 825-4600 / (888) 830-5648.
In short, it's a unique, practical blend of advanced ham radio engineering, professional RF safety infrastructure, educational outreach, and aviation support—all centered around the 4KS runway in rural Kansas. If you're local or planning a visit (or if this is for a specific project), more details are readily available on the linked sites.
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