Antenna Lectures: Introduction and Examples

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What is the primary function of an antenna?

To filter out unwanted signals

To generate new signals

To amplify signals

To convert electrical signals into electromagnetic signals or vice versa (correct)

Which of the following statements about antenna size is correct?

Antenna size is inversely proportional to the frequency (correct)

Antenna size is directly proportional to the frequency

Antenna size is independent of the frequency

Antenna size is determined by the power of the signal

What is the Half Power Beamwidth (HPBW) of an antenna with a field pattern given by $E(\theta) = \cos^2(\theta)$ for $0^\circ \leq \theta \leq 90^\circ$?

65.72° (correct)

32.85°

180°

90°

Which of the following statements about antennas is true?

Antennas are passive elements that don't amplify signals Signup and view all the answers

Which of the following is not a step in the solution to determine the HPBW of the antenna with field pattern $E(\theta) = \cos^2(\theta)$?

Set $E$ proportional to $\sqrt{P}$ Signup and view all the answers

What is the power at half power beamwidth as per the given information?

0.5 Signup and view all the answers

What is the angle (in degrees) approximately at which the first null beamwidth occurs?

30 Signup and view all the answers

In terms of radiation pattern, how do shapes of Microstrip patch elements differ?

They have different radiation patterns. Signup and view all the answers

Why are Microstrip antennas considered easy to install according to the text?

As they can be fabricated on painted circuit boards. Signup and view all the answers

What is a key characteristic of Microstrip antennas mentioned in the text?

Directional radiation pattern Signup and view all the answers

What is a limitation of Microstrip Line Feed as mentioned in the text?

Increases surface waves & feed radiation Signup and view all the answers

What is the advantage of a coaxial probe feed for microstrip antennas?

Easy fabrication and easy modelling Signup and view all the answers

Which feed type is described as having the most difficult fabrication process?

Aperture coupled feed Signup and view all the answers

Which of the following is NOT listed as an advantage of microstrip antennas?

High radiation efficiency Signup and view all the answers

What is the cause of the fringing effect in microstrip antennas?

Magnetic field lines passing through an air gap Signup and view all the answers

In the given example, what is the value of the dielectric constant of the substrate material?

2.2 Signup and view all the answers

What is the height of the substrate used in the given example?

0.1588 cm Signup and view all the answers

What does the field pattern 𝐸(𝜃) = 𝑐𝑜𝑠(𝜃)cos (2𝜃) represent?

Power pattern Signup and view all the answers

How is Half Power Beamwidth (HPBW) calculated?

By taking the square root of 0.5 Signup and view all the answers

What is the First Null Beamwidth (FNBW) for an antenna with 𝑈(𝜃) = cos²(𝜃) cos²(3𝜃)?

90 degrees Signup and view all the answers

In the context of the text, what does 'cos−1( 0)' represent?

First Null Beamwidth calculation Signup and view all the answers

Why is it mentioned 'trial and error method' in the solution?

To estimate the Half Power Beamwidth Signup and view all the answers

What is one key similarity between determining HPBW and FNBW?

Both require taking the cosine value at specific angles Signup and view all the answers

What is the formula for calculating the width (W) in the given context?

$W = v_0^2 \sqrt{2f_r \varepsilon_r + 1}$ Signup and view all the answers

In the provided solution, what does '𝜖𝑟' represent?

Effective dielectric constant Signup and view all the answers

How is the effective dielectric constant ('𝜖𝑟𝑒𝑓𝑓') calculated in the given scenario?

$\varepsilon_{r_{eff}} = 1 + \frac{1}{2.2} + \frac{12}{(2.2)^2}$ Signup and view all the answers

What does 'Δ𝐿' stand for in the context of the solution provided?

Effective length Signup and view all the answers

Why is the effective dielectric constant ('𝜖𝑟𝑒𝑓𝑓') somewhat less than the substrate's dielectric constant?

Due to air presence affecting the fields from microstrip conductor Signup and view all the answers

How is the final value for 'L' calculated in the given scenario?

$L = 0.906cm$ Signup and view all the answers