Radio and television reception How to select antenna for watching digital terrestrial television?

General rules for the construction of antenna installations for DVB-T and DVB-T2 television.

Correct installation of the receiving antenna is the basis for the reception of digital television regardless of the high class television or STB receiver. The most important issues to be addressed before performing the antenna receiving installation:

  1. The approximate location of the broadcasting facility in relation to the planned reception site.
  2. The number of the channel broadcast by the broadcasting facility(-ies).
  3. The emission power (ERP) of the channel broadcast by the broadcasting facility(-ies).
  4. Polarization of the DVB-T/DVB-T2 channel planned for reception.

Getting acquainted with the site of the broadcasting facility on the map will allow us to find out at what distance we are from the broadcasting facility and from what direction (azimuth) we should start attempts to receive the TV signal. If reception is not successful directly from the broadcasting facility site, attempts should be made to deflect the antenna to other azimuths, which will be especially applicable when broadcasting facility is not visible directly or there is more than one broadcasting station emitting the program via the same channel.

By tilting the antenna to other directions, we will try to receive the signal: reflected from the surrounding infrastructure or from another transmitting station, and the most advantageous, coming from the summation of signals from more than one transmitting station. A special case with which we can meet will be the implementation of a receiving antenna system in built-up areas, where it will not be possible to lift the antenna above the buildings. In this situation, we can receive a signal of good quality, reflected from an adjacent building being in a different direction than the broadcasting facility.

Information about the power and distance from the transmitting station will allow us to assess what a good chance we have for the realization of the correct reception and which broadcasting facility to choose for the first reception attempts. Generally, we choose the nearest facility with the highest ERP power, and the receiving antenna will be as high as possible to exceed the building located in the direction of this broadcasting facility.

The polarity of the receiving antenna (or the position of the receiving element in its axis) should be consistent with the polarity of the transmitting station, which is of key importance to obtain the maximum level of the reception signal at a given location. In order to receive many broadcasting stations operating in different polarizations, with a high signal level it is acceptable to use one antenna with polarization set in accordance with the station with a weaker signal.

There is no universal recipe for choosing the perfect antenna. With increasing distance from the broadcasting facility, the requirements for antenna installation are increasing. It should be remembered that in digital terrestrial television in the DVB-T standard, signal reflections from terrain obstacles add up and improve the reception.

Antenna installation should be selected according to local reception conditions. The general rule is to choose directional antennas, if possible without amplifiers. We do not recommend using room antennas.

The height of the antenna suspension is very important. The higher the antenna will be, the better. All terrain obstacles located between the transmitting structure and the receiving antenna obscuring the view have an impact on the reception quality. Remember that on DVB-T digital television, reflected signals add up to improve reception.

When selecting elements of a new antenna installation, one should be guided by technical parameters and antenna selection to local conditions, not price and marketing descriptions such as “DVB-T” or “DVB-T2” antenna, “enables HDTV reception” or its impressive stylish colours.

For the needs of receiving construction, the antenna system should be selected that best suits the antenna for a given location:

Room antennas:

The use of room antennas to receive terrestrial DVB-T or DVB-T2 digital television is limited to places with high signal strength, a short distance from the broadcasting facility. These antennas are characterized by low energy gain and, unfortunately, very often the use of high gain amplifiers. This means that despite the attractive appearance and often high price, this antenna may not be enough. Even if we receive a signal, the reception may be susceptible to local interference (walking around the apartment, switching on electrical devices, cars passing through the window) manifested by temporary interruptions in reception, “frozen images” or characteristic squares on the screen.

A variation of room antennas are panel antennas designed for outdoor installation. As a rule, they are characterized by the same electrical construction and the same reception problems (low antenna gain and amplifier that often aggravates the reception), therefore their use, although very convenient, is also limited to a small area around the transmitter.

Mesh antennas:

Another type of antenna designed for use in close proximity to the broadcasting facility is a mesh antenna. Antennas of this type are often equipped with an integrated balun and a broadband amplifier. Unfortunately, their quality depends on the implementation. If possible, grid antennas with amplifiers should be avoided.

Multi-element Yagi antennas:

The Yagi antenna is a directional antenna. In urban conditions, close to the sending facility, usually a multi-element antenna is enough, small, light and easy to install. The antenna should be equipped with a balun. With a weak signal it is possible to use a properly selected amplifier, but certainly better effects (more stable reception) will give the use of an antenna with a larger number of elements. For larger distances, it will be necessary to use more complex multi-element antennas. The real range of DVB-T reception at radiated power ERP 100kW is about 70 km, sometimes even more.

How to select an antenna:

Each type of antenna has its advantages and disadvantages as well as typical areas of application. Antenna selection should take into account the local reception conditions as well as the location and emission parameters of the broadcasting facility from which we intend to receive the signal. In case of problems with the selection or installation of antenna system components, it is best to outsource it to a specialist service.

Under typical reception conditions, you can use the instructions in the table below. However, due to differences in transmission parameters from individual broadcasting facilities as well as local reception conditions, this information can only be an indication that needs to be verified locally.

Type of antenna Max. 10km 10-30km 30-50km >50km
Room YES
Directional YES YES YES
Directional with high gain YES YES YES

When purchasing the elements of a new receiving antenna, pay attention to a few basic parameters:

Range of operational frequencies

For the purpose of receiving DVB-T or DVB-T2 digital terrestrial television, it is best to use broadband antennas, including the UHF band, 21 – 60 channels and the VHF band, from 5 to 12 channels.

Balun and antenna amplifier.

The balun is basically a standard and necessary element for connecting contemporary coaxial (coaxial) cables to the antenna. Only certain types of antennas (e.g. logarithmic and periodic) do not require such an element. When receiving weak signals from more distant broadcasting facilities, it may be necessary to use a properly selected amplifier. It should be an amplifier with the lowest possible noise ratio (so-called “low-noise” or “low-noise”). It should be noted here that the use of the amplifier should be avoided because they are often the reason for the disrupted reception of television and can become a source of interference to other devices in our home or in our neighbours.

Aerial energy gain and directionality.

This is an important parameter, it depends on how the antenna will deal with the weak signals that will come to receive it. The general rule is that the greater the antenna gain, the better. Remember, amplification of the signal through the amplifier will not replace the energy gain of the antenna! At longer distances from the transmitter and in more difficult reception conditions, the directionality of the antenna (higher efficiency of reception from one direction in relation to the other) allows at least partially to eliminate unwanted or disturbing signals. Keep in mind our table because the use of a good high gain antenna (multi-element antenna) in some cases may bring more problems with reception than benefits.

In addition to the antenna itself, the antenna cable is a very important element. It should be a good quality cable, intended for antenna installations. For outdoor installations, use weather-proof cable. It is also important that all plugs and connectors are well seated at the ends of the cable.

Antenna amplifier will not replace antenna gain, too strong amplifier can degrade or prevent digital TV reception and cause interference to neighbours.

In conclusion, the antenna installation is a key element of the television reception system. If it is necessary to replace or modernize it, it is worth to do it with particular attention, which will ensure long and trouble-free TV reception.

Let’s choose the solution that best suits our needs (oversizing is not always meaningful), always trying to ensure quality – better electrical and mechanical quality of the antenna, better quality of reception and longer operation. Avoid the cheapest antennas and accessories, pay attention to the materials used for production, metallization, galvanic coatings, plastics and general quality and durability.

Let’s not be fooled by manufacturers and sellers that the antenna they offer is “DVB-T2 ready” or “DVB-T2 UHD ready” and therefore costs more. Antennas packed in foil labelled “TV antenna” and “DVB-T2 antenna” in attractive packaging, standing next to it is often made of the same materials, in the same technologies, has similar parameters, dimensions, etc.

We install the antenna by directing it to the broadcasting facility broadcasting the DVB-T program, we assess whether there are any potential obstacles on the way that could impede or disrupt our reception. During the installation, we can control the quality and level of the received signal using your DVB-T or STB receiver. Let us try to get the receiving antenna as high as possible above ground level – it definitely improves the quality of reception. It is good to be aware that in some cases we may need a galvanized steel pipe 1.5 – 2 m long, which we will have to mount, for example, a special chimney band on our roof and we will install a receiving antenna on top of it.

Always remember and let our neighbours know: Be careful with amplifiers, use them only where the level of the receiving signal is too small and the use of an antenna with a higher gain is impossible mechanically! Particularly close to high-power broadcasting facilities may occur situations that the use of a receiving antenna with an amplifier will result in distortion of the received image.

We use good quality coaxial cables, connectors, plugs, distributors, crossovers. On such elements, we can lose a lot of useful signal if they are corroded, ill-fitting mechanically and electrically or simply made of poor quality materials.