Question

The main advantage of super heterodyne receiver is ________.

• A. simple circuit
• B. better tracking
• C. improvement in selectivity and sensitivity
• D. better alignment

Hint:

Superheterodyne receivers convert all signals to a common intermediate frequency (IF), enabling excellent filtering, which leads to superior selectivity and sensitivity.

Answer 1

The Correct Option is C

To understand the advantage of a superheterodyne receiver, let us first break down how it works and then examine its specific benefits:
Step 1: What is a Superheterodyne Receiver?
A superheterodyne receiver is an advanced radio receiver design that converts all received signals to a fixed intermediate frequency (IF) before processing. It was invented by Edwin Armstrong to overcome limitations in selectivity and sensitivity present in early receiver designs.
Step 2: How It Works – Block by Block:
Antenna: Captures electromagnetic signals from different frequencies.
RF Amplifier: Amplifies weak received signals to a more usable level.
Mixer: Combines the incoming RF signal with a locally generated frequency from a Local Oscillator (LO) to produce the Intermediate Frequency (IF).
IF Filter and Amplifier: Processes the IF signal, where filtering is easier and more precise due to the fixed frequency.
Detector/Demodulator: Extracts the audio or data signal from the modulated IF.
Audio Amplifier: Final stage that boosts the output for speakers or other output devices.
Step 3: What Makes This Design Special?
Fixed IF Stage: Since all incoming frequencies are converted to the same IF, only one fixed-tuned filter and amplifier are needed. This makes it possible to build highly selective and sensitive IF stages.
High Selectivity: The ability to reject adjacent unwanted signals or noise improves because filters at IF can be made narrow and stable.
High Sensitivity: The signal is amplified early and at multiple stages without distortion or loss, allowing detection of even weak signals.
Step 4: Why Not the Other Options?
Option (1) Simple Circuit: This is false because a superheterodyne receiver is more complex than a TRF receiver.
Option (2) Better Tracking: Tracking is typically associated with tuning circuits, not a core feature of superheterodyne.
Option (4) Better Alignment: Alignment refers to calibration; although important, it is not the main advantage.
Conclusion:
The standout feature of a superheterodyne receiver is that it dramatically enhances the receiver’s selectivity (ability to isolate a specific frequency) and sensitivity (ability to detect faint signals) through intermediate frequency processing and fixed filtering.
Final Answer: (3) improvement in selectivity and sensitivity