H35-911 practice question 5 of 15

The radiated power of an antenna is basically distributed to the side lobe.

Full set: 60 questions
Answer options
A: True
B: False
Correct Answer:
FALSE
Explanation

The statement is incorrect. The primary function of a directional antenna is to concentrate its radiated power into a specific, intended direction. This concentration of power forms the main lobe, which contains the vast majority of the antenna's radiated energy. Side lobes are residual, smaller lobes of radiation in unintended directions. In antenna design, side lobes are considered undesirable as they represent wasted power and a potential source of interference. Therefore, the goal is to maximize the power in the main lobe while minimizing the power distributed to the side lobes.

Why Incorrect

The statement is false because it fundamentally misrepresents how antennas distribute power. Power is basically and intentionally distributed to the main lobe, not the side lobes.

References

1. University Courseware:

Source: MIT OpenCourseWare

Course 6.661

"Receivers

Antennas

and Signals."

Reference: Lecture 12 Notes

"Antenna Fundamentals." The notes define the main lobe as "the lobe containing the direction of maximum radiation" and side lobes as "smaller lobes" away from the main direction. The diagrams and discussion on antenna directivity and gain implicitly and explicitly confirm that power is concentrated in the main lobe. (Available via MIT OCW website).

2. Vendor Documentation:

Source: Huawei

"5G Antenna White Paper."

Reference: Section 2.1

"Massive MIMO Key Technologies." This section explains that technologies like beamforming are used to "focus energy to form high-gain narrow beams" that are directed towards users. This "high-gain narrow beam" is the main lobe. The objective is to improve signal strength for the intended user and reduce interference to others

which is achieved by maximizing main lobe power and suppressing side lobes.

3. Peer-reviewed Academic Publications / Foundational Textbooks:

Source: Balanis

C. A. (2016). Antenna Theory: Analysis and Design (4th ed.). Wiley.

Reference: Chapter 2

Section 2.4

"Radiation Lobes." The text defines the main lobe as the lobe with the maximum radiation. It explicitly states

"A side lobe is a radiation lobe in any direction other than the intended lobe." The entire principle of antenna gain

discussed in Section 2.5

is based on the ability of an antenna to concentrate energy in the main lobe compared to an isotropic radiator.

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