Articles

All You Need To Know About Antennas

Posted by Michael Gonzalez on in Antenna, Articles, Television Broadcast, Wireless Trasmission

A television antenna is designed for receiving wireless broadcast television signals. It can classified based on the

  • Frequency and size
  • Directivity
  • Physical Construction
  • Application

Frequency and Size

Antennas of television used for High Frequency differ from the ones used for Very High Frequency. The wavelengths of these are different at different frequencies. They even differ in size to spread out signals at the correct wavelength. They are transmitted at the frequency from 41 to 250MHz in the Very High Frequency (VHF), and 470 to 960 MHz in the Ultra High Frequency (UHF) in various countries. They’re manufactured based on the indoor type and outdoor type. In the indoor, they’re present on the top or beside the television. Whereas outdoor have antennas present on the top of the house.

Directivity

Antennas can be either Omni-directional, sectorial or directive. The antennas which are Omni-directional radiate in the same pattern in 360 degrees and the most common types are the Dipole-Type and the Ground Plane.

The Sectorial antennas unlike omni-directional radiate only in a specific area. It can be as broad as 180 degrees, or as narrow as 60 degrees. Directive antennas beam width is narrower even than the sectorial antennas. There are used for long distance links and its types are the Yagi, the biquad, the horn, the helicoidal, etc. Usually the best antennas are those which are highly directive as they can easily discard signals from other sides. The directivity can be determined through the front-to-back ratio which is measured in decibels.

AntennaPhysical Construction

The construction of the Antennas can be done in many different ways. It can range from simple wires to parabolic dishes, up to coffee cans. Based on the design, they are again divided into 4.

Wire antennas— these are regularly employed in lower frequency.

Aperture antennas— these are utilised in microwave frequency.

Printed Planar Antennas— these are used in microwave frequency.

Reflector antennas—these are used for operating at microwave frequency.

Application

Based on the application, the antennas are categorised into two. They’re Base Station and Point-to-point. Depending on the purpose, different antenna types are used. Base Stations are used for multipoint access, whereas Point-to-Point case is used for connecting two single locations together.

Non- directional or omni-directional antennas are fundamental dipoles or monopoles. Whereas; the complex, directional antennas consists of compilation of elements like dipoles, or make use of one active and numerous passive elements, like in the Yagi antenna.

Broadcast Filters and Combiners

Posted by Michael Gonzalez on in Antennas Masts & Towers, Articles, Broadcast & Management Systems, Broadcasting Networks, Cable, Connectors & Conductor Machineries, Content & Asset Management, Studio Production, Transmission And Distribution

Broadcast sector is a very wide and dynamic industry. Not only in terms of delivering or broadcasting information through different media, but also the technical infrastructure behind the screen plays a very vital role for its successful deliverance. Filters and Combiners are the components that connect the technical infrastructure at studios, stations and even at domestic broadcast equipment like video, audio, data transformation service systems, etc.

Broadcast Filters and Combiners

In the recent years a lot of innovations evolved and came in availability to the industry. One of the major technical advancements in combiner and filters for broadcast industry is through the entrance of the modules. The combiner units forms the backbone of media set network. Shively Labs, a broadcast equipment designing and manufacturing company came up with balanced combiner modules that allow any number of stations to be combined into a common antenna. Systems have been designed to handle up to 21 analog stations, along with their digital counterparts. The frequency spacings as close as 0.8 MHz are routine, even on large systems and the design allows stations to be added in any frequency order without the need to reconfigure the existing combiner chain – making them ideal for sites where future expansion is planned.

Many industry events like NABSHOW are venues for companies to showcase and introduce their new products. Filters and combiners presented at NABSHOW 2012 attracted attention of the market. Radio Frequency Systems has added technology innovations and new models to its line of filters and combiners with the introduction of PeakPower+ at the event.

Trend of Combining Units

A lot of scope is recognized by the manufacturers for the combiners and filters. The evidence is the evolution ofCombining Units, which is a replacement for lot of technical material surrounded by the broadcast equipment.

The PeakPower+ line of filters and combiners is specifically aimed at safely sustaining the very high peak power of digital television, and represents a major breakthrough in coaxial filter technology.

By removing the peak power handling limitations imposed on digital transmitter filter & combiner systems, PeakPower+ TM allows broadcast operators to safely run their systems without fear of interruptions, and boost revenues by adding digital channels and services to their existing infrastructure, without having to upgrade to waveguide technology.

Features

  • Very compact for easy integration into equipment.
  • Very low insertion loss for filter size, (lowest IL for each size).
  • Highest power rating for size/class of filter.
  • Tunable over full UHF band (470 – 862 MHz)
  • Adjustable bandwidth, available for 6, 7 & 8 MHz channels for ALL global applications.
  • Symmetrical response characteristics.
  • External, non-invasive coupling adjustment
  • Tunable for both ETSI and ISDB-T critical and non-critical, and ATSC applications.
  • -5 to 55 degree ambient temperature operation.

DSL line combiners are from Pace plc that subscribers get “splittered” service, where DSL and telephone service are terminated into the home on separate lines. This has 2 types. Line Inline Filter with Giveback Jack and Line Inline Filter with Giveback Jack are the types available in this product.

Bandpass filters and Transmitting Combiners from Com-Tech Italia SpA are 4 types each.

  • UHF TV Filters / Combiners
  • VHF B.III TV Filters / Combiners
  • VHF B.I-II TV Filters / Combiners
  • VHF B.III DAB Filters / Combiners

The Bandpass Filter is a terrestrial broadcasting of the television signal for Analog TV (ATV) and Digital TV: DVB-T, DVB-H, ATSC (DTV), needs a high degree of linearity by the output amplifiers. So, the more an amplifier is pushed in power, the more it generates products from distortion within and outside the transmitted channel.

The Com-Tech Transmitting Combiners and Multiplexers are devices that can able to sum various inputs with different frequencies on a single output and this is a suitable application in television broadcasting as transmission of various channels take place on a single broadband antenna.

AISG/3GPP- compatible DC connections of Spinner Atlanta’s is a model that allows the transfer of control signals and power supply to antenna pre-amplifiers. The core advantage is that all the frequency combiners are suitable for indoor and outdoor installation.

While, in broadcast applications multi-channel combiners are used to combine the signals of two or several channels on to one antenna. Depending on the channel spacing Spinner has solutions for combining.

  • When the channels are close together or when retuning is required filter combiners are used mainly.
  • The starpoint and manifold combiners are usually designed as 2- or 3-way combiners.
  • The strechline combiners are 2-way combiners when spacing is larger than three channels.

The broadcast industry market scope and demand is there at every corner of the globe. The quality and robustness of its products and services from the industry players would build up an enviable reputation for the manufacturers.