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What makes a good antenna? |
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A good GSM antenna As an antenna serves as the electrical power conversion device between a circuit and the air, the keys to it’s efficiency are as follows:
- Input characteristics with the contact point on the circuit side
- Radiation characteristics from the contact point to the air
Input Characteristics of a good GSM antenna
Electric power is supplied efficiently to the antenna without reflecting back into the circuit at the feeding point
If the impedance between the antenna and the feed line is not matched correctly, the signal will reflect back and no power will be supplied to the antenna.
Radiation Characteristics The power supplied to the antenna is not lost within the antenna but is transmitted as a radio wave.
If the antenna is made of high loss material (conductors and dielectrics), then the power that was supplied to the antenna will be dissipated into heat and lost. The characteristics of a general antenna are shown below. Input Characteristics- Frequency –Return loss chart Where the return loss is low, indicates that the antenna is well matched at that frequency.
- Frequency – VSWR chart In the same way as the return loss chart, a low VSWR value shows a good matching of the antenna.
- Bandwidth The antenna is good to the extent of good matching and the width of the frequency domain.
Radiation Characteristics- Radiation Pattern The strength of the antenna emission is displayed. It shows that antennas emit well in their projected direction. It is usually displayed in three planes (XY, YZ and ZX planes).
- Gain [dBd] Given as a ratio to a standard antenna (half wave dipole). Usually displayed as the average of the three planes (XY, YZ and ZX planes). Designated as a combination of the vertical and horizontal polarity power gains.
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