The physical sizes of the transmitter and reciever antenna in a communication system are :

Options

A. independent of both carrier and modulation frequency
B. inversely proportional to carrier frequency
C. inversely proportional to modulation frequency
D. proportional to carrier frequency

Answer

To solve the question regarding the physical sizes of transmitter and receiver antennas in a communication system, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Antenna Size**:
The size of an antenna is crucial in communication systems as it affects the efficiency and effectiveness of signal transmission and reception.

2. **Relationship Between Antenna Size and Frequency**:
It is known that the physical size of an antenna is inversely proportional to the frequency of the carrier wave. This means that as the frequency increases, the size of the antenna decreases, and vice versa.

Mathematically, we can express this relationship as:
\[ h \propto \frac{1}{f} \]
where \( h \) is the size of the antenna and \( f \) is the frequency of the carrier wave.

3. **Analyzing the Options**:
Given the options in the question, we need to identify which one correctly describes the relationship between the antenna size and the frequency. The options are:
- A) Independent of both
- B) Inversely proportional to carrier frequency
- C) Directly proportional to carrier frequency
- D) None of the above

4. **Selecting the Correct Option**:
Based on our understanding from step 2, we can conclude that the size of the antenna is indeed inversely proportional to the carrier frequency. Therefore, the correct option is:
- **Option B: Inversely proportional to carrier frequency**.

### Final Answer:
The physical sizes of the transmitter and receiver antennas in a communication system are inversely proportional to the carrier frequency.

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