# Antenna Gain - Gain Comaprison(Transfer) Method

• jegues
In summary, the problem involves measuring and calculating the gains and effective areas of different antennas using various methods and equations. It is important to carefully check all calculations and assumptions to ensure accuracy.
jegues

## Homework Statement

1) H-plane patterns of rectangular microstrip antenna, open-ended waveguide antenna and small horn antenna are measured and shown in the table below. Assuming the small horn antenna as reference antenna with a gain of $$G_{smallhorn} = 8dB$$ Obtain the gains of the other two antennas using gain-comparison method.

2) Using the gains derived in problem 1 and assuming f = 10.5GHz, obtain the effective area for the rectangular microstrip and open-ended waveguide antennas.

3) Calculate the aperture efficiency of the microstrip and open-ended waveguide antennas using the results of problem 2. (The physical aperture of the rectangular microstrip antenna is 0.8×1.25 cm^2 and the open-ended waveguide has a physical aperture size of 1×2.25 cm^2)

4) The E- and H-plane patterns of rectangular microstrip antenna and open-ended waveguide antenna are measured and the HPBWs are shown in the table below.

Use the approximate formula,

$$D = \frac{26000}{HPBW_{E} * HPBW_{H}}$$

to calculate the gains of the antennas (assuming lossless antennas). Compare these results with the results obtained in problem 1 and determine which one is more exact if they were not equal.

## The Attempt at a Solution

I did my solution attempt in Mathcad so that if I have to change any of the parameters I can quickly solve the problem again.

Since there is no simple way to convert my math to text or latex I've attached an image of my solution attempt below.

Questions

My calculated gains from part 1) don't seem to be lining up with the gains from part 4).

Am I correct to use the power values in Watts and not dB in part 1)?

Is the approximate formula in 4) meant for HPBW values given in radians?

#### Attachments

• Lab4TableP1.JPG
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• Lab4TableP4.JPG
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• Attempt1.jpg
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I would like to clarify a few things before addressing your questions. First, can you provide the table of H-plane patterns and HPBWs mentioned in the problem statement? This will help me understand the exact values you are working with. Also, in your solution attempt, can you provide more details on how you calculated the gains and effective areas for the antennas? This will help me better understand your approach and provide more accurate feedback.

To address your questions, yes, it is correct to use power values in Watts for part 1). dB is a logarithmic unit and needs to be converted back to its linear form (Watts) before performing calculations.

For part 4), the approximate formula is typically used for HPBW values given in degrees, not radians. However, you can convert radians to degrees by multiplying by 180/pi. Also, please note that the formula may not give an exact result, but it can provide a good approximation.

Without seeing the actual values and calculations, it is difficult for me to determine which solution is more accurate. However, I would suggest double-checking your calculations and making sure all parameters are consistent (e.g. using the same units for all values). Additionally, you can try using different methods or equations to calculate the gains and compare the results to see which one gives a more accurate result.

Overall, it is important to carefully check all calculations and assumptions made in your solution attempt to ensure accuracy. Also, make sure to clearly state any assumptions or approximations made in your solution so that others can understand and verify your results.

## What is antenna gain?

Antenna gain is a measure of the ability of an antenna to radiate or receive electromagnetic waves in a specific direction. It is usually expressed in decibels (dB) and is a comparison of the antenna's radiation pattern to that of an ideal isotropic antenna.

## What is the gain comparison method?

The gain comparison method is a technique used to measure the gain of an antenna. It involves comparing the antenna's radiation pattern to that of a reference antenna, usually an isotropic antenna, and calculating the ratio of their power densities.

## How is gain comparison method different from other methods of measuring antenna gain?

The gain comparison method is different from other methods, such as the three antenna method or the standard gain method, because it does not require any specialized equipment or calibration. It relies on the principle of reciprocity, which states that the gain of an antenna transmitting is equal to its gain when receiving.

## What are the advantages of using the gain comparison method?

One of the main advantages of the gain comparison method is its simplicity and low cost. It can be performed using basic equipment and does not require any specialized knowledge. Additionally, it can be used for a wide range of antenna types and frequencies.

## Are there any limitations to the gain comparison method?

The gain comparison method is limited by the accuracy of the reference antenna used and the environment in which the measurements are taken. It may also be affected by reflections and obstructions in the surrounding area. Additionally, it may not be suitable for measuring the gain of very high gain antennas.

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