LAS Study Guide 2026: How to Pass on Your First Attempt

What You Are Actually Studying

Line and Antenna Sweeping is a competency credential from ETA International focused on commissioning and verifying antenna systems: the antenna, the feedline, the connectors, the grounding and lightning-protection hardware, and the records that prove the system was built and tested correctly. If you have landed here searching for a general definition first, our explainer on what LAS is covers the basics, and the page on what LAS stands for confirms the exact meaning so there is no confusion with other credentials that share the acronym.

The syllabus is built from the issuer's Line and Antenna Sweep (LAS) Competency Requirements document, copyright 2022, which lists eleven knowledge categories. This guide summarizes those categories by name and shows you how to prioritize them. Treat the official PDF at etai.org/comps/LAS_comps.pdf as the controlling document for detailed coverage; where this article and the PDF differ, the PDF wins.

The Gate Before the Knowledge Exam

This credential is not a "register and sit the test" experience. The sequence matters, and misunderstanding it is one of the more common ways candidates lose time.

1. ETA-approved course. You complete an approved course first.
2. Fee. The associated fee is part of the process before testing.
3. Hands-on exam. A practical, hands-on exam precedes the knowledge exam, which fits a credential whose whole point is operating test equipment correctly.
4. Knowledge exam. The written knowledge exam follows.

One honest caveat: the exact number of knowledge-exam questions, the time limit and the passing score are not something this guide can state, and you should not trust any source that quotes them without citing ETA directly. Confirm those details with ETA or your course provider. For the broader picture of money and logistics, see our breakdowns of LAS certification cost, exam dates and scheduling and the passing score.

Two Routes, Not One

There is a journeyman CET route and a standalone route, and they are distinct. The journeyman CET route additionally requires CETa or General Communications Technician Level 1. If you are pursuing LAS on its own, you are on the standalone route and that extra prerequisite does not apply. Read our LAS requirements guide before you commit to a path, because choosing the wrong route wastes both time and fees.

Recommended Background

Prior familiarity with RF, land mobile radio, cellular work or amateur radio, plus antenna and feedline knowledge, is recommended. It is not a substitute for study, but candidates who already know why a mismatched connector matters will move through Domains 2, 4, 6 and 7 much faster than someone meeting reflection coefficient for the first time.

The Eleven Knowledge Categories, Grouped by How You Will Study Them

Rather than memorizing eleven names in isolation, group them by the kind of thinking each demands. For a deeper domain-by-domain walkthrough, see our complete guide to all 11 LAS content areas.

Building the RF and Math Core

Domains 2 and 3 are the foundation. Everything the instrument displays is expressed in these terms, so shaky fundamentals will undermine your performance in the FDR domains later.

Cable, Connector and Antenna Material

Domain 4: Coaxial Cable Fundamentals

Expect to explain how cable construction relates to characteristic impedance, with common 50-ohm systems as the standard case. Know skin effect, the equivalent capacitance, inductance and resistance of a line, and how cable dimensions and frequency affect both loss and impedance. Velocity factor deserves special attention because it appears in two places: FDR distance measurements and tuned stubs. A wrong velocity factor setting makes every distance-to-fault reading wrong, which connects this domain directly to the instrument domains.

Domain 5: Coaxial Cable Installation

This domain is about doing the physical work so that a sweep is reliable and the system survives. Topics include hangers, mounting and spacing for cable management and impedance; code- and standard-based grounding requirements and grounding kits; kit installation for reliable sweeps; weatherproofing of connectors and ground kits; bend-radius requirements and the fault signatures that violations leave; and lightning-protection components, their connections, and how they appear in FDR traces. That last item is a good example of how the physical and instrument domains interlock.

Domain 6: RF Connectors and Connectorization

Know appropriate connector types and their specifications, installation tools, cable preparation, and torque requirements and the errors that come from ignoring them. Passive intermodulation and its effects belong here too. Poorly prepared or under-torqued connectors are among the most common physical faults a sweep reveals, so connect each preparation mistake in your notes to the trace signature it would produce.

Domain 7: Antennas and Antenna Theory

This is a broad domain and the heaviest on raw theory. Cover electric and magnetic fields, electromagnetic waves and polarization; the specifications bandwidth, match, gain, beamwidth and tilt; and the example types dipole, isotropic, omnidirectional, directional and quarter-wave. You should be able to perform wavelength calculations, relate feedline velocity factor to antenna length, read radiation patterns and coverage, and understand gain measurement against the dipole, isotropic and quarter-wave references. Effective radiated power, including gains and losses, is fair game, as are FDR bandwidth measurement, mechanical versus electrical tilt, polarization choices and mounting effects.

The FDR Domains: Where Most Study Time Belongs

Domains 8 through 11 all center on the frequency domain reflectometer. That is four of eleven categories on one instrument family, and they reward hands-on familiarity more than rote recall. An important scope point: full commissioning sweeps use FDR-capable LMR equipment. A stand-alone VNA alone is not the full-sweep verification method described in the syllabus, though Domain 1 expects you to know the role and limits of a VNA and to compare TDR and FDR methods.

Why Records Matter More Than You Expect

Domains 1 and 10 both mention commissioning records, saved traces, sweep records and as-built diagrams. Beginners often treat documentation as an afterthought. The credential does not. A baseline trace saved with a sensible name and correct instrument date and time is what makes later troubleshooting in Domain 11 possible, since fault-finding by baseline comparison requires a baseline that exists and can be identified.

What the Questions Tend to Reward

Because the exact exam format (question count, duration, passing score) has not been verified here, avoid building your preparation around assumptions about it. You can, however, prepare for the kinds of thinking the syllabus language implies.

• Relationship questions. Given one quantity (return loss, VSWR, reflection coefficient), identify or convert to another.
• Calculation questions. Decibel arithmetic, wavelength, velocity factor effects and ERP with gains and losses.
• Procedure questions. What to do first, what triggers recalibration, which setting must be chosen before another.
• Interpretation questions. A described trace feature at a measured distance, and which component or fault it most plausibly maps to.
• Cause-and-effect questions. A physical installation error (excess bend, poor weatherproofing, wrong torque) and the signature or performance consequence.

For an honest read on overall difficulty, see how hard the LAS exam is, and for what is and is not known about outcomes, our page on the LAS pass rate.

A Domain-Ordered Study Sequence

Generic scheduling advice matters less than ordering the domains sensibly. The logic below follows dependency: math and theory first, hardware second, instrument work last but with the most time. Adjust the number of weeks to your experience and course schedule.

If you are working from a condensed reference, keep our LAS cheat sheet alongside your notes, and use the main practice test site to check retention after each block.

Practice, Review and Final-Week Priorities

Practice questions are most useful when you review the reasoning, not just the score. After each set, sort missed questions by domain rather than by date. Patterns show up quickly: a cluster of misses in Domain 3 usually means arithmetic habits, while misses in Domain 9 usually mean you recall the facts but have not practiced mapping a distance on a trace to a physical component.

The final week is for consolidation, not new material. A reasonable priority list:

1. Re-read the official competency list at etai.org/comps/LAS_comps.pdf and tick off each item you can explain without notes.
2. Redo decibel and wavelength problems cold, without looking at solved examples.
3. Walk through the full instrument workflow from memory: frequency range, calibration, distance and cable settings, markers and limit lines, save and name the trace.
4. Review the relationships among return loss, VSWR and reflection coefficient until conversions feel routine.
5. Take timed sets on the practice test site to rehearse working under mild pressure.

Who Uses This Credential

The skills tested map to work done on wireless and radio infrastructure: land mobile radio systems, cellular and other commercial or private radio systems, and the antenna and feedline plants that support them. People in tower, installation, commissioning and maintenance roles are the natural audience, and the credential speaks directly to the quality-assurance side of that work, proving a system was swept and documented. We avoid quoting salary figures or job counts here because none are verified for this credential; for the career side, see our guides to LAS jobs, the salary analysis and the question of whether the certification is worth it.

Frequently Asked Questions