Link Design For Satellites

VSAT Satellite Antenna

VSAT Satellite Antenna

Satellites are designed to deliver voice/data services, broadband net solutions, television broadcast and communications to distant areas. Satellite link technology includes both a downlink and also an uplink to facilitate the transfer of data. The satellite Uplink will transfer from an earth terminal to the satellite and Downlink connects the satellite to the receiving earth terminal.

The signal quality in the uplink connection relies on just how solid the signal is transferred from the source terminal as well as exactly how the satellite receives it. On the downlink side, a high signal quality depends upon how strong the satellite retransmits the signal and exactly how the earth station can receive it.

Earth satellite antennas are most often classified into three categories.

  • VSAT which stands for Very Small Aperture Terminal, will have a smaller antenna size, generally with a diameter from 1/3 meter to 1 meter.
  • Small earth stations will have an antenna diameter of somewhere between 1 and 10 meters in size.
  • Large stations will usually have a antenna dish diameter larger than 10 meters.  Most are smaller than 30 meters, however larger antenna do exist.

There are three earth terminal system specifications that should be taken into consideration when making satellite telecommunication links.

  1. Transmitter EIRP (Effective Isotropic Radiated Power) gauges the signal power sent out from the transfer earth station.
  2. Figure of Merit is the measure of the sensitivity of the receiving station and the signal quality received there.
  3. System Noise Temperature determines the quantity of noise power produced by the receive earth station.

A good satellite link design will maximize the link data throughput while minimizing the error rate of the transmitted signal (called the BER or bit error rate). The design must meet requirements for BER within the constraints of transmission power and RF bandwidth.

The major concern in design as well as evaluation of a satellite link is to determine C/N in which C is the obtained provider power in the earth station/satellite and N is the sound plus noise (caused by nearby earth station antennas) power in the receiver.

ATM Microwave Pyramidal Horn AntennasHorn Antennas and Pyramidal Microwave Horn Antennas are used quite often in microwave RF satellite link designs and applications. Horn antennas like those shown at right are available from http://www.atmmicrowave.com

Loss because of rainfall is the most crucial problems to the transmission of a satellite signal. Rainfall attenuation is a function of rainfall rates at the earth station as well as satellite link carrier frequency. Typical rainfall rates in a given area can be obtained from the division of Meteorology of that nation. Rain effects end up being extreme depending on the size of the raindrops. Added transfer power is needed to conquer the maximum attenuation generated by the rain if the satellite link is to preserved throughout a rainstorm without interruption. Precise assessment of expected rain loss needs to be made when evaluating satellite link criteria.

Satellite Earth Station Antenna Maintenance

The earth antenna look angle (azimuth & elevation) can be determined utilizing the longitude of the geosynchronous satellite plus the latitude as well as longitude of the planet station. Antenna loss has to be reviewed carefully in satellite link designs. It must be considered carefully since it affects both transfer and receive antennas.

Vive la France

A summary of upcoming editorial coverage and related events for August through October including the EuMW in August, Satellite and Radio Communications issue and Military Microwaves supplement in September and Passive and Control Components in October.

Source: Microwave Journal Editor – Blogs

Comparing PCBs for Microstrip and Grounded Coplanar Waveguide

Circuit designers must often select a circuit technology, such as microstrip or grounded coplanar waveguide (GCPW) circuitry, with a particular design and circuit material to achieve optimum performance. Circuit technologies, such as microstrip and GCPW, each have their strengths and weaknesses, and it may help to take a closer look at these two circuit technologies in particular to see how they stack up.

Source: Microwave Journal Editor – Blogs

New Business Opportunities Taking Shape

 The Obama administration has opened up relations with Cuba and Iran to some degree – do these actions have any significant business opportunities for RF and microwave companies? Cuba is a very underserved with wireless infrastructure so perhaps a large rollout could produce significant additional business for components although it is not a large country. 

Source: Microwave Journal Editor – Blogs

How Wireless Works

Skyworks is pleased to announce the launch of “How Wireless Works” – a short, animated video explaining what happens each time we use our smartphones, tablets or other wireless device. Wireless connectivity is everywhere and an integral part of our daily lives. Yet very few understand how it all works. This non-technical video is fun, informative and created for those who want to simply understand what enables all those seamless connections. Watch it directly at http://www.skyworksinc.com/HowWirelessWorks.aspx

ATMMicrowave Product Listings

ATMMicrowave.com Product Listings on RFEngineeringDirectory.com

Advanced Technical Materials, Inc. ( ATMMicrowave.com ) has listed 11 of it’s product lines in the RFEngineeringDirectory.com RF Business Directory, one of the primary websites for Microwave RF Component Manufacturers.

The listings describe the major lines of microwave components manufactured by ATM, and offer brief explanations of the components available in those product lines.

Here is a list of the pages in the directory

For more details on microwave products offered by ATM, please visit the links above to see the RF Engineering Directory listings or visit the website directly at http://www.atmmicrowave.com

Hall of Famers

Humankind, which includes me, has a primal fascination with those who have achieved excellence, fame or notoriety in their field.

Source: Microwave Journal Editor – Blogs