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Key Facts: Engineer Radio Electronic Communication Exam

100 items

Official written examination paper length (5 subjects × 20 items)

KCA 전파전자통신기사 page (cq.or.kr) and 출제기준 2025-2028

150 minutes

Written exam duration (2 hours 30 minutes)

KCA qualification page and 2026 examination schedule

40 / 60

Passing standard: 40% individual subject floor (과락) and 60% overall average

KCA 전파전자통신기사 passing criteria

KRW 19,400

Written examination registration fee

KCA qualification portal (cq.or.kr), verified 2026-09-20

KRW 24,600

Practical examination registration fee

KCA qualification portal (cq.or.kr), verified 2026-09-20

2 years

Written-test exemption after a written pass

National Technical Qualifications Act Enforcement Decree Article 21

전파전자통신기사 is South Korea's Engineer-grade radio and maritime electronics credential (Q-Net jmCd 1195, MSIT / KCA). The official written exam has 100 MCQs across five subjects (20 per subject, 150 minutes) with a 40% per-subject floor (과락) and 60% overall average, followed by a 20-minute hands-on practical in maritime communication practice. Official KCA fees are KRW 19,400 (written) and KRW 24,600 (practical). OpenExamPrep provides an independent 100-question English MCQ practice bank.

Sample Engineer Radio Electronic Communication Practice Questions

Try these sample questions to review concepts for the Engineer Radio Electronic Communication exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a single-phase full-wave bridge rectifier feeding a resistive load, what is the relationship between the peak secondary voltage \(V_m\) and the ideal average (DC) load voltage, neglecting diode drops?
A.\(V_{dc} = 2 V_m / \pi\)
B.\(V_{dc} = V_m / \pi\)
C.\(V_{dc} = V_m / 2\)
D.\(V_{dc} = V_m / \sqrt{2}\)
Explanation: A full-wave bridge uses both half-cycles of the AC secondary, so the average of a rectified sine wave is \(2 V_m / \pi\). A half-wave rectifier averages to \(V_m / \pi\) because it uses only one polarity.
2What is the principal function of the capacitor filter (평활회로) connected across the load of a radio-equipment rectifier?
A.To step the AC secondary voltage up or down
B.To convert the load current from DC back into AC
C.To reduce ripple by storing charge near the peak of each rectified half-cycle
D.To provide galvanic isolation between the mains and the transmitter
Explanation: A reservoir (smoothing) capacitor charges near the rectified peak and discharges into the load between peaks, lowering the AC ripple superimposed on the DC output. Transformers handle voltage change and isolation; inverters would recreate AC.
3In a series linear voltage regulator, which element is placed in series with the unregulated input to drop the extra voltage and hold the output nearly constant?
A.A series-pass transistor (or MOSFET) controlled by an error amplifier
B.A shunt zener diode alone, with no series control device
C.A series resonant LC tank tuned to the mains frequency
D.A series coupling capacitor that blocks DC from the load
Explanation: A series regulator uses a pass transistor as a controlled series resistance. An error amplifier compares the output with a reference and adjusts the pass device so that input-minus-drop equals the desired DC output.
4For a small-signal common-emitter BJT amplifier with unbypassed emitter resistor \(R_E\), which statement best describes voltage gain and input resistance?
A.Voltage gain is reduced to about \(R_C / R_E\) and input resistance is increased
B.Voltage gain is \(R_C / r_e\) and input resistance is very low
C.Voltage gain becomes infinite because of positive feedback
D.The stage inverts neither voltage nor current
Explanation: An unbypassed emitter resistor introduces series-series degeneration: voltage gain falls toward \(R_C / R_E\) (plus \(r_e\)), and looking into the base the input resistance rises. The stage still inverts voltage.
5Compared with a BJT used as a small-signal RF amplifier, a JFET (or depletion MOSFET) in the same role is typically preferred when the designer needs:
A.A low-noise, high input-impedance voltage-controlled device
B.Much higher transconductance at the same bias current
C.A strictly current-controlled input that always draws base current
D.Class C collector efficiencies above 90 percent
Explanation: FETs are voltage-controlled and present a very high input impedance, which is useful at receiver fronts and in high-impedance RF stages. BJTs usually offer higher \(g_m\) per milliamp; Class C efficiency is a bias-class issue, not a FET-versus-BJT guarantee.
6Negative voltage feedback around an amplifier is used in radio transceivers primarily because it:
A.Increases closed-loop gain without bound
B.Reduces gain stability, bandwidth, and distortion all at once
C.Stabilizes gain, extends bandwidth, and reduces distortion and output impedance (voltage sampling)
D.Converts the amplifier into an oscillator by satisfying Barkhausen’s criterion
Explanation: Negative feedback trades raw open-loop gain for a more stable closed-loop gain, wider bandwidth, lower distortion, and—when voltage is sampled—lower output impedance. Oscillation requires the loop to meet Barkhausen conditions with positive (or improperly phased) feedback.
7An ideal op-amp inverting amplifier has input resistor \(R_{in} = 10\,\text{k}\Omega\) and feedback resistor \(R_f = 47\,\text{k}\Omega\). What is the closed-loop voltage gain \(v_o / v_s\)?
A.\(-4.7\)
B.\(+4.7\)
C.\(+0.21\)
D.\(-47\)
Explanation: Ideal inverting gain is \(-R_f / R_{in} = -47/10 = -4.7\). The minus sign is the virtual-ground inversion through the input resistor.
8What is the theoretical maximum collector (or drain) efficiency of an ideal Class B transformer-coupled push-pull RF power amplifier?
A.25 percent
B.50 percent
C.78.5 percent (\(\pi/4\))
D.100 percent
Explanation: Each Class B device conducts 180°, and the ideal transformer-coupled push-pull efficiency is \(\pi/4 \approx 78.5\%\). Class A dissipates bias current continuously (25% resistive, 50% transformer-coupled max). Class C can exceed 78.5% by using a smaller conduction angle.
9A Colpitts oscillator uses a split capacitor \(C_1, C_2\) across an inductor \(L\). Neglecting device capacitance, the oscillation frequency is approximately:
A.\(f = 1 / (2\pi \sqrt{L C_1})\)
B.\(f = 1 / (2\pi \sqrt{L (C_1 + C_2)})\)
C.\(f = 1 / (2\pi \sqrt{L C_{eq}})\) where \(C_{eq} = C_1 C_2 / (C_1 + C_2)\)
D.\(f = (C_1 + C_2) / (2\pi \sqrt{L})\)
Explanation: In the Colpitts tank the two capacitors are in series for the resonant path, so \(C_{eq} = C_1 C_2 /(C_1+C_2)\) and \(f = 1/(2\pi\sqrt{L C_{eq}})\). A Hartley oscillator splits the inductance instead.
10A 555 timer in astable mode has \(R_1 = 4\,\text{k}\Omega\), \(R_2 = 5\,\text{k}\Omega\), and \(C = 0.1\,\mu\text{F}\). Using \(f = 1.44 / [(R_1 + 2 R_2) C]\), the output frequency is nearest to:
A.480 Hz
B.720 Hz
C.1.03 kHz
D.3.6 kHz
Explanation: \(R_1 + 2 R_2 = 4\,\text{k}\Omega + 10\,\text{k}\Omega = 14\,\text{k}\Omega\). Then \((R_1 + 2 R_2)C = 14\times 10^{3} \times 0.1\times 10^{-6} = 1.4\times 10^{-3}\). Frequency is \(1.44 / 1.4\times 10^{-3} \approx 1.03\,\text{kHz}\).

About the Engineer Radio Electronic Communication Exam

Engineer Radio Electronic Communication (전파전자통신기사) is South Korea's Engineer-grade national technical qualification for radio-system operation, antenna practice, and maritime distress communications, administered by the Korea Communications Agency (한국방송통신전파진흥원 / KCA) under the Ministry of Science and ICT (과학기술정보통신부). KCA's official job description covers radio communications and radio-equipment design and repair for ship-to-shore and ship-to-ship public, distress, urgency, and safety traffic on passenger ships, merchant ships, and fishing vessels. The written examination tests 100 four-option items across five subjects: Digital Electronic Circuits, Radio Communication Systems, Antenna System Operation, Maritime Communication Operation, and Radio Regulations. Passing candidates then sit a 20-minute hands-on practical in maritime communication practice (해상통신실무). OpenExamPrep provides an independent English-language MCQ study adaptation; it is not an official translation of the Korean paper and does not simulate the 작업형 practical.

Exam sponsor: Korea Communications Agency (한국방송통신전파진흥원 / KCA) / Ministry of Science and ICT (과학기술정보통신부). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Written paper covering 디지털전자회로 (Digital Electronic Circuits), 무선통신시스템 (Radio Communication Systems), 안테나시스템 운용 (Antenna System Operation), 해상통신운용 (Maritime Communication Operation), and 전파관계법규 (Radio Regulations) with 20 items each (100 items / 150 minutes), followed by a 20-minute hands-on practical in 해상통신실무. OpenExamPrep study weights cover all five written subjects.

Time Limit

150 minutes for the five written subjects; practical: 20-minute hands-on work-type practical

Passing Score

Written: 40+ per subject (과락 floor) and 60% average; practical: 60/100

Exam / Certification Fees

KRW 19,400 written / KRW 24,600 practical (KCA, 2026-09-20)

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

20%

Digital Electronic Circuits (디지털전자회로)

Rectifiers, smoothing filters, and voltage regulators used in radio power supplies; transistor, FET, feedback, operational, and power amplifiers; sine and non-sine oscillators and waveform-conversion circuits; analog and digital modulation circuits; Boolean algebra; combinational and sequential logic; flip-flops, counters, and semiconductor memory.

20%

Radio Communication Systems (무선통신시스템)

AM, SSB, and FM transceivers; ASK, FSK, PSK, QAM, and OFDM digital radios; radar, GNSS, AIS, LRIT, and related navigation radios; microwave relay and Inmarsat-C/FB maritime satellite terminals; CDMA/WCDMA/LTE mobile systems; RF specifications (VSWR, frequency tolerance, AGC, spurious emissions); batteries, inverters, and UPS; and GMDSS equipment function tests for VHF/MF/HF, DSC, EPIRB, and SART.

20%

Antenna System Operation (안테나시스템 운용)

Electromagnetic-wave characteristics, Maxwell equations and the Poynting theorem, feeder design, VSWR and Smith-chart matching, waveguides, dipole/loop/Yagi/parabolic and maritime GMDSS antennas, ionospheric and tropospheric propagation (MUF, LUF, FOT, fading), and free-space path-loss and antenna-power calculations.

20%

Maritime Communication Operation (해상통신운용)

ITU Radio Regulations and SOLAS GMDSS operating rules, VHF and MF/HF radiotelephony, IMO Standard Marine Communication Phrases, DSC distress alerting, EPIRB/SART/NAVTEX procedures, 27 MHz fishing-band SSB, coast-station selection, and marine meteorological broadcasts.

20%

Radio Regulations (전파관계법규)

Korea Radio Waves Act purpose, definitions, radio-resource allocation and assignment, radio-station licensing and inspection, radio-operator duties, distress/urgency/safety priority, communications security, broadcasting and telecommunication equipment conformity assessment, radio-wave usage fees, ITU/SOLAS/GMDSS provisions, and information-and-communications construction technical standards.

Preparing for the Engineer Radio Electronic Communication Exam

What You Need to Know

  • Passing score: Written: 40+ per subject (과락 floor) and 60% average; practical: 60/100
  • Assessment: Written paper covering 디지털전자회로 (Digital Electronic Circuits), 무선통신시스템 (Radio Communication Systems), 안테나시스템 운용 (Antenna System Operation), 해상통신운용 (Maritime Communication Operation), and 전파관계법규 (Radio Regulations) with 20 items each (100 items / 150 minutes), followed by a 20-minute hands-on practical in 해상통신실무. OpenExamPrep study weights cover all five written subjects.
  • Time limit: 150 minutes for the five written subjects; practical: 20-minute hands-on work-type practical
  • Exam / certification fees: KRW 19,400 written / KRW 24,600 practical (KCA, 2026-09-20) Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Engineer Radio Electronic Communication: Suggested Study Strategy

1Treat 디지털전자회로 as two blocks: analog radio hardware (rectifiers, amplifiers, oscillators, modulators) and digital logic (Boolean, flip-flops, counters, memory). The official 출제기준 weights both.
2Protect the 40% 과락 floor in every subject. Five subjects of 20 items means eight correct answers in each paper are the minimum; an otherwise high total still fails if one subject is below 40.
3Memorize GMDSS watch and distress frequencies used in both 무선통신시스템 and 해상통신운용: VHF DSC Channel 70 (156.525 MHz), VHF radiotelephony Channel 16 (156.800 MHz), MF DSC 2187.5 kHz, MF voice 2182 kHz, and HF DSC 8414.5 kHz.
4For 전파관계법규, learn the Radio Waves Act concepts of frequency allocation versus assignment, station inspection before operation, operator qualification, communications secrecy, and conformity-assessment categories rather than memorizing unverified article numbers.

Frequently Asked Questions

What is the official structure of the Engineer Radio Electronic Communication examination?

The official qualification has two stages. The written paper is a 150-minute CBT of 100 four-option items (20 items in each of five subjects: Digital Electronic Circuits, Radio Communication Systems, Antenna System Operation, Maritime Communication Operation, and Radio Regulations). The practical is a 20-minute hands-on work-type examination (작업형) in Maritime Communication Practical Practice (해상통신실무), scored out of 100 points.

What are the passing criteria and the 'gwarak' (과락) minimum floor?

To pass the written examination, a candidate must score at least 40 points in each subject (8 of 20 items) and a 60-point overall average. Scoring below 40 in any subject is an automatic fail (과락), even if the overall average is high. The practical requires at least 60 points out of 100.

What are the official fees and where is registration conducted?

As published on the Korea Communications Agency (KCA) qualification page (cq.or.kr, checked 2026-09-20), the written fee is KRW 19,400 and the practical fee is KRW 24,600. Registration is submitted on the KCA portal during the published national sitting windows.

Is this practice question bank an official translation of the KCA test?

No. The official KCA examination is conducted in Korean, and the practical stage is a hands-on 작업형 on maritime communications equipment. This OpenExamPrep resource is an independent English-language MCQ study adaptation. It is not an official translation, not a substitute for Korean-language exam practice, and not a simulation of the 20-minute practical.

How long is a written exam pass valid for attempting the practical stage?

Under Article 21 of the Enforcement Decree of the National Technical Qualifications Act (국가기술자격법 시행령 제21조), a written pass exempts that qualification's written paper for 2 years from the written-pass date (합격한 날). If fewer than two sittings occur in that window, one additional following sitting is also exempted.