--- title: "Role of antenna; optical fiber pros and cons" subject: "Basic Electronics Engineering" chapter: 5 key: "semester_2/basic_electronics_engineering:antenna-role-optical" source: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/antenna-role-optical site: BCT Engineering --- # Role of antenna; optical fiber pros and cons Basic Electronics Engineering · Chapter 5: Communication System - Asked in: 2070 Bhadra, 2+4 marks - Video: [optical fibre in detail advantages disadvantages of optical fibre](https://www.youtube.com/watch?v=8mdNcLg_cXQ) — IOE Electronics and communication engineering - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/antenna-role-optical - Whole chapter: https://www.bctengineer.com/md/semester_2/basic_electronics_engineering/chapter-5 ## Question Discuss the role of antenna in communication system. What are the advantages and disadvantages of optical fiber communication? ## Short answer An antenna converts electrical signals to/from EM waves, provides impedance matching, and adds directivity/gain for wireless communication. Optical fiber advantages: high bandwidth, low loss, EMI immunity, security, small size; disadvantages: high cost, fragile, difficult splicing, no power carrying. ## Answer #### Role of antenna in a communication system An antenna is a transducer that converts electrical signals into electromagnetic waves and vice versa. - **Transmitting antenna:** takes the modulated high-frequency signal from the transmitter through the feed line and radiates it as EM waves into free space. - **Receiving antenna:** intercepts the EM waves from space and converts them to a weak electrical signal for the receiver. - It matches the transmission line to free space (impedance matching), so that maximum power is transferred. - It gives directivity and gain, concentrating power in the wanted direction, which increases range and reduces interference. Without an antenna, wireless communication is not possible. #### Optical fiber communication **Advantages** 1. Very high bandwidth and data rate. 2. Low attenuation, so long distances with few repeaters. 3. No EMI or crosstalk. 4. Secure, hard to tap. 5. Light, small and flexible. 6. Safe, no electrical hazard. **Disadvantages** 1. Terminal equipment and installation are costly. 2. Jointing and splicing need skill and special tools. 3. Fibers are fragile and cannot be bent sharply. 4. Cannot carry electric power. 5. Maintenance and repair of breaks are difficult. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What does an antenna do in a communication system? A. Converts electrical signals to EM waves (and EM waves back to electrical signals) B. Amplifies the message signal before modulation C. Stores the signal until the receiver is ready D. Converts light signals into electrical signals Answer: A. The answer states this: Converts electrical signals to EM waves (and EM waves back to electrical signals). (Key point: Antenna as transducer) 2. Why does an antenna match the transmission line to free space? A. So that the signal frequency is doubled B. So that maximum power is transferred C. So that the signal is converted to light D. So that noise is added to the signal Answer: B. The answer states this: So that maximum power is transferred. (Key point: Impedance matching) 3. What is the benefit of antenna directivity and gain? A. Power is spread equally so every direction gets the signal B. The antenna needs no feed line C. Power is concentrated in the wanted direction, raising range and reducing interference D. The signal needs no modulation Answer: C. The answer states this: Power is concentrated in the wanted direction, raising range and reducing interference. (Key point: Directivity and gain) 4. Which is a disadvantage of optical fiber communication? A. It suffers from EMI and crosstalk B. It is easy to tap C. It has low bandwidth D. It cannot carry electric power Answer: D. The answer states this: It cannot carry electric power. 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