The television like any other kind of receiver of radio waves – require an antenna to capture energy efficient high frequency, and this is processed and decoded images and sounds generated by the TV.
In the areas away from the transmission towers, the incoming signal is weak and the quality of the image and sound is considerably affected.
Cartoon of a man sitting in front of the television.
To increase the quality of the signal received by the TV, must increase the gain of the antenna (conversion capacity of the electromagnetic waves in high frequency energy or electric current of high frequency which is directed towards the receptor, which is expressed in decibels [ dB ]).
Summing up in simple terms, the more gain our antenna has, the better the perceived signal will be.
Summary
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- 1 which antenna to use
- 2 Channel frequency
- 3 Build an antenna for television
- 4 Some models proposed
- 1 Universal television antenna (channels 2 to 13)
- 2 High gain antenna (for extremely weak signals)
- 5 See also
- 6 Sources
Which antenna to use
As the transmission towers are located at a fixed point (which do not move from position) the use of directional antennas is suggested, which once oriented towards the transmitter will give us the maximum possible gain of said antenna.
Channel frequency
Each television channel transmits on a certain radio frequency , hence if we want to improve the reception of a particular channel we must have an antenna that is designed to have its maximum gain on the frequency of this channel.
Television broadcasts are divided into two bands
VHF and UHF or low channels (2 to 6) and high channels (7 to 69)
Some examples of channels and their corresponding frequencies:
| CHANNEL | Frequency (MHz) | CHANNEL | Frequency (MHz) |
| two | 54 – 60 | 7 | 176 – 180 |
| 3 | 60 – 66 | 8 | 180 – 186 |
| 4 | 66 – 72 | 9 | 186 – 192 |
| 5 | 76 – 82 | 10 | 192 -198 |
| 6 | 82 – 88 | eleven | 198 – 204 |
| 12 | 204 – 210 | 13 | 210 – 216 |
Build an antenna for television
It is suggested to calculate the antenna for half wave since otherwise the antenna would sometimes be too large depending on the frequency.
How is a 1/2 wave calculated?
Using the following formula = 142.5 divided by the frequency in MHz
For example: the average frequency of Channel 10 Television is 195 MHz .
So:
142.5 divided by 195 = 0.73 m = 73 cm
Some proposed models
Universal television antenna (channels 2 to 13)
The small folded dipole or director should calculate the half wave for the channel or the highest frequency.
The large folded dipole should calculate the half wave for the channel or the average frequency.
The rear element or reflector should calculate the half wave for the channel or the lowest frequency.
67 cm, 168 cm and 250 cm, respectively, are suggested; although – for practical reasons – it is left at 67, 168 and 177 cm respectively.
High gain antenna (for extremely weak signals)
For the central dipole or excited element, the half wave of the central average channel must be calculated.
79 cm is suggested.
For reflector elements, a 60% wavelength must be calculated
95cm is suggested for each.
The total length of the entire reflector system will be equivalent to 2 waves.
3.16 meters is suggested.
These two models of Yagi antennas are designed for low and high channels respectively, thus achieving greater gain in both bands, which with a single antenna is poorly stable.
