All posts by Sheetal Rajput

LNB the Crucial Satellite TV Transmission Device

Low Noise Block Downconverter – LNB – also called a low noise block – is a receiving device that is fitted on satellite dish antennas for satellite TV reception.

It collects radio frequency waves beamed by a relevant satellite, on the dish antenna, and converts them into signals to be sent through coaxial cable to the receiver or a set-top box placed indoors of a home.

The set-top box powers the LNB, using the same coaxial cable, which feeds the dish antennas signals into it. It is the front section of a satellite receiver which down converts the block of frequencies to lower block of intermediate frequencies (IF).

The down-conversion of the signals is crucial for it to be carried to the indoor satellite TV receiver-through coaxial cable.

If original satellite signals were to be used straightaway for TV transmission, it would require the use of an expensive waveguide technology which is impractical. And therefore, the use of LNB gains significance.

Further, Intelligent designing techniques and the use of expensive and high-performance components such as HEMTs reduces the noise generated by LNBs which makes it a perfect choice for satellite TV transmission system.

Among the different types of low noise block downconverters, widely used are 1) the Multi-output and 2) Quattro LNBs, for DTH TV systems.

Multi-output LNB’s are a single feed horn with multiple ports for multiple tuners. The Quattro LNB is used for a shared dish antenna system to deliver signals to multiple users. Many models are available from RADITEK Inc. with details on the website.

SSPA – Used in SATCOM (Satellite Communications)

SSPA stands for Solid State Power Amplifier. Amplifiers, irrespective of their types, are used to enhance the amplitude of the radio frequency received by the satellite antennas.

Specifically used in satellite communication technology, it is an active device that drives the transmitter.

Intensifying the amplitude of the RF results in relative increase of noise, distortion, and loss of power and therefore, a suitable SSPA is used for varied applications.

However, incredible advances made in solid state technology have made the solid state power amplifier the most accomplished and sound device in the field of the satellite communication field, and especially over the traveling wave tube amplifier (TWTA).

The tenacious workhorse devices of amplifiers are the Gallium Arsenide (GaAs) or Gallium Nitrate (GaN) transistors, a component that does the bulk of the amplification work.

Gallium Arsenide (GaAs) SSPA system is popularly in use for over 4 decades now due to its quick replacement advantage though in terms of temperature tolerance GaN-based amplifiers fare better.

Gallium Nitrate (GaN) based solid state amplifiers were the first among the two to be developed by the department of defense for its use as jammers of the improvised explosion device (IED) in Iraq and other electronic warfare systems.

Commercial use of Gallium Nitrate (GaN) based SSPA, initially, was developed initially for low frequency L, S, and C band satellites. Now, it is also been used for higher frequencies like X, Ku, and Ka frequency bands. Both models are available from RADITEK Inc with details on the website.

About Waveguide Rotary Joints

Used in microwave communication applications, a waveguide rotary joint allows one part to be rotated while connected to a fixed part. An example is a rotating radar antenna

In the moving parts, the electrical continuity is achieved using λ/4-chokes which do away with metal contacts.

Waveguide rotary joint facilitates the continuous and regular flow of radio frequency with low insertion loss and well enhanced power-handling capabilities.

Waveguide rotary joint is used in all the high-frequency transmission systems like satellite communication, radars, air traffic control, and surveillance systems.

Different waveguide rotary joints are available which can handle various frequency ranges up to 40 GHz.

Top-quality waveguide rotary joint are now available with very low VSVR -voltage standing wave ratio- and low insertion loss.

Waveguide rotary joint can be custom designed to suit different applications.

The most common mechanical configurations of the waveguide rotary joints are;

U-style-where both the ports are at a right angle to the rotation axis,

L-style-where one port is at a right angle to the rotating axis.

I-style-both transmission lines are in straight lines.

F-Style-One port at right angle rotates and the in-line port is fixed into housing.

These configurations bring versatility and freedom electrical connections.

Raditek Inc. offers all types of  Waveguide rotary joints check out their website.

Utility of Dielectric Resonator Oscillators

Dielectric resonator oscillators or DROs make use of dielectric resonator as a frequency-determining element to generate frequencies signals with very high stability and low micro-phonics

The physical dimensions of dialectical material used, it shape-rectangular or a disc-and the dielectric constant, determine the resonant frequency of the dielectric resonator oscillators.

The resonant frequency of the dielectric resonator oscillators can vary based on the variance in the bias voltage capacitance of the varactor diode. (electrical tuning)

The frequency of these dielectric resonator oscillators is fixed. However, by using a self-locking screw a slight mechanical tuning over a small band, can be achieved successfully.

Dielectric resonator oscillators have better stability as compared to free-running cavity oscillators. They also have a better power efficiency.

Dielectric resonator oscillators have superior frequency pulling (oscillators’ sensitivity to VSWR changes – factor as compared to other oscillators).

Dielectric resonator oscillators have a high Q-factor and a low phase-noise. They exhibit superior temperature stability.

Dielectric resonator oscillators are available in a range of wide varieties to suit all applications.

Dielectric resonator oscillators are mainly used in micro-wave snd millimeter wave electronic oscillators (3 to 42GHz) to control the radio wave generated.

Raditek offers a full range of DRO and PLO (phase locked DRO) on its website.

Microwave Amplifier – A Vital Electronic Device

Microwave Amplifiers take in a very low-level signal input from a lossy transmission medium to amplify it to a calibrated level with a minimal additive noise.

Microwave amplifiers are solid-state amplifiers. These amplifiers have a frequency range of 1 to 100GHz.

Microwave amplifiers are extensively used in electromagnetic compatibility systems (EMC), electromagnetic interference (EMI), defense systems, medical and diagnostic systems, laboratory, and field testing appliances, Telecommunication’s and Satcom.

A transistor used in the microwave amplifiers is the main active component that amplifies the RF signals.

These days, advanced transistors have Gallium Arsenide (GaAs) or Gallium Nitrate (GaN) which is responsible for actual amplification of the input signal.

Gallium Arsenide – GaAs has the best linearity and Gallium Nitrate – GaN – has the best of efficiency.

Besides, the applications mentioned above and other numerous applications, microwave amplifiers are used for high power radio frequency generation for radio transmitters, inter-stage amplifiers, and amplifiers used in cancer treatment equipment and radio frequency receivers.

Microwave amplifiers are specified mainly by its frequency coverage and output power. Power gain by microwave amplifiers is a factor of the source and load impedance.

Microwave amplifiers generate a lot of heat which necessitates the use of state-of-art in-built cooling systems like convection heat sink or forced air cooling to maintain ambient operating temperatures. Water cooling systems are also used in ultra-high power microwave amplifiers.

Customers’ due-diligence is crucial to ascertain their requirements which would help to determine the right type of microwave amplifier needed. Raditek offers a wide range on its website.

Power Splitter – An Important Device for Radio Frequency Equipment

A Power splitter is one of the most conventional passive devices which receives an input signal and delivers multiple output signals to different output ports, with a specific phase and amplitude characteristics.

In other words, the power splitter apportions the signal input, received by the base station antenna, to multiple output ports for its further processing.

There are different power splitters known by the number of splits or output power/signals it can generate from a single input power source, namely – two-way power splitter, three-way power splitter, and a four-way power splitter.

A power splitter is a reciprocal passive device, and so the same power splitter can be used as a combiner – multiple input signal vectors combined into one output signal vector. In words, the vector sum of the signals will appear as a single output at the splitter output port.

The following functions can be achieved by using a power splitter or a combiner-the power splitter in a reciprocal application.

  1. 1. Add or subtract signals vectorially.

  2. 2. Attain multi-phase proportional output signals from different sources.

  3. 3. Split an input signal into multiple output signals-from 2 ports to 32 ports.

  4. 4. Combine signals from multiple input sources to obtain a single port output.

  5. 5. Attain a capability to get RF logic arrangements.

Power splitter is available in conventional housing and T-style housing which covers all wireless band frequencies from 200MHz to 18GHz and narrowband to multi-octave versions too. Raditek offers a wide range on it’s website.

Band Pass Filter – The Concierge of Radio Frequencies

Band Pass Filter is an electronic device that permits the frequencies of a selected range to pass while baring other signals at unsolicited/unrequired frequencies from going getting into the receiver set and create disturbances thereby.

The main functions of a band pass filter circuit to pass or amplify certain frequencies and accentuate other frequencies. It restricts the bandwidth of the output signal to the band assigned for transmission.

This functionality of a band pass filter prevents the transmitter from interfering with other wireless stations.

There are four major types of filters 1) The low pass filter 2) The high pass filter 2 the band pass filter and 4) the band stop filter.

Please note that the word “Low” and “High” do not indicate any absolute frequency values, but nonetheless, are relative values of the cut-off frequency.

Further, the band pass filter can be placed in 2 categories-1) Active and 2) Passive, depending upon their responsivity and capability of dealing with high and low frequencies.

Passive band pass filter is most amenable to a frequency range of 100Hz to 300MHz. Hi-tech designs can extend the use of passive filters in the gigahertz range.

Active band pass filters are very effective in dealing with very low frequencies-nearing 0Hz. They can yield a voltage gain, which the passive band filters cannot. Active band pass filters are unsuitable for very-high-frequency applications.

Band pass filter perform a critical role in application like power supplies, audio electronics, and radio communications.

Many filters can be found on the Raditek website.

SSPA – Inextricable Satellite Communication Device

SSPA stands for a solid-state power amplifier. This is one among the two types of microwave amplifier, the other one being traveling wave tube amplifier-TWTA.

Amplifiers come in varied shapes and sizes, especially in the satellite communication sector. Whether it is SSPAs, vacuum-tube amplifiers, magnetic amplifiers or negative resistance amplifiers, all have their inherent usefulness and drawback or inapplicability, basis their utilization.

Irrespective of the types of amplifiers, it is the most important component which makes satellite communications possible by enhancing the power of radio frequencies received by antennas.

An SSPA system based on Gallium Arsenide (GaAs) is in use for over 4 decades now and are popular.

However, Gallium Nitrate (GaN) based SSPA was first designed by the department of defense, in 2000 and were used for improvised explosion device-IED-jammers in Iraq.

Commercial use of Gallium Nitrate (GaN) based SSPA, initially, was developed for low-frequency L, S and C band satellite communications. Now, it is also been used for higher frequencies like X, Ku, and Ka frequency bands.

SSPA based on GaAs and GaN transistors are used for microwave and millimeter-wave electronics purposes like satellite, radar, communications and electronic warfare systems.

The temperature is a crucial aspect of SSPA’s performance, Gallium Nitrate-GaN-based SSPA can perform better, without degradation, as compared to a GaAs SSPA.

Gallium Nitrate based SSPA is voted to be the most intrinsically reliable SSPA compared to other amplifiers, as it has a reduced maintenance down-time that results in OPEX cost saving.

Many GaAs and GaN SSPA can be found on the Raditek website.

LNB – The Marvel Component That Made the DTH Concept Possible

It is a modern-day technological miracle that we are able to receive crisp pictures, clear sound in our television sets, from satellites, orbiting thousands of miles up in the space.

The electronics that made this possible is a wonderful weather-proof device called the LNB-Low noise block downconverters.

Low noise block downconverters-known as LNB-is a receiving device that is installed on the DTH dish antenna used for TV reception.

Satellite signals become very weak during the time it travels over 22000 miles to reach a dish antenna. The “dish” part of an antenna works like a lens that focuses most possible signals on LNB and therefore the curvature on the dish.

LNB receives low-level microwave frequency beamed by the satellite that is projected by the dish antenna, amplifies it, down converts the signals to a lower frequency band and sends them through a cable to a receiving set in an apartment or a building.

Therefore, the LNBs perform two functions-1) that of an amplifier and 2) and that of the down converter of super-high satellite signals to a lower frequency conducive for TV reception.

Both these functions are important to deliver the signal through a regular cable.

However, it is found that only older satellite dishes used LNBs. The newer and the modern versions of dish antennas use a more compact LNBF-Low Noise Block Downconverters plus Freedom.

As the industry has totally shifted to the use of LNBFs so much so that they don’t even highlight the “F”-for freedom-anymore. LNBFs have completely replaced the LNBs.

Power Splitter – The Amicable Segregator

The power splitter is used, mostly in radio technology. Radio Frequency (RF) power splitters are used to split or divide a single frequency line into several lines or pathways.

When the power splitters are used the other way round, it turns into a combiner where it combines more than one frequency line into a single line. Therefore, this power splitter is also a combiner. It is a reciprocal device.

Types of Power Splitters / Combiners: There are two types of power splitter/combiner.

1)  Resistive Power Splitter: These power splitters use resistors hence they are able to maintain the required impedance of the system. The use of resistors introduces a loss above the loss caused by splitting. However, it provides credible performance over a broad range of frequencies and maintains the required impedance match.

2)  Hybrid Power Splitter: These power splitters use transformers which result in a low level of power loss due to the splitting action. The major loss in this type of splitters is the loss that arises out of the splitting process as the same signal is shared a number of outputs.

Different types of power splitter/combiners are available in the trade, for example that can be used to split and/or combine signals in any ratio by selecting the correct values of the components used in their configuration.

There is some inherent power loss with the insertion of splitters/combiners in any system as no component is totally loss-free. These losses cannot be calculated in absolute numbers; however, it can be minimized.