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.

Verotec contributes to THAAD systems

Terminal High Altitude Area Defense (THAAD) is a U.S. Army anti-ballistic missile system designed to shoot down short, medium, and intermediate ballistic missiles in their terminal phase using a hit-to-kill approach. The interceptor missile carries no warhead, but relies on the kinetic energy of the direct impact to destroy the incoming threat. Verotec has supplied Lockheed with custom 4U, 750 mm deep 19 inch VPX chassis that houses a signal integrity testing subsystem, the reconfigurable and analogue Self Test Subsystem.

RF Power Shakeout

 ABI Research just released numbers for the RF power market from 2014 showing that RF Power Semiconductors for Wireless Infrastructure “blew off the charts in 2014”. China and the Asia-Pacific region in general continued to be the main drivers for the RF Power Semiconductor devices that were sold into the mobile wireless infrastructure segment. 

Source: Microwave Journal Editor – Blogs

RF Power Shake Out

 ABI Research just released numbers for the RF power market from 2014 showing that RF Power Semiconductors for Wireless Infrastructure “blew off the charts in 2014”. China and the Asia-Pacific region in general continued to be the main drivers for the RF Power Semiconductor devices that were sold into the mobile wireless infrastructure segment. 

Source: Microwave Journal Editor – Blogs

ANADIGICS Wi-Fi infrastructure solutions selected by Buffalo for new 802.11ac router

ANADIGICS Inc., a world leader in radio frequency (RF) solutions, announced that the company is shipping production volumes of its AND0281 and AND0581S Wi-Fi infrastructure front-end integrated circuits (FEICs) to Buffalo for the new WXR-1750DHP router. This high-performance 802.11ac router features three antennas with simultaneous dual-band capabilities and four gigabit wired Ethernet ports.

Silence Filter Harmonics with Composite Circuit Materials

 Microstrip edge-coupled bandpass filters (BPFs) can help clean the spectrum around a desired center frequency. Fabricated on printed-circuit-board (PCB) materials, these compact filters can be integrated with other circuit functions to provide dependable filtering of communications bands and high-frequency signals for a wide range of applications. 

Source: Microwave Journal Editor – Blogs

Peregrine Semiconductor awarded QML certification

Peregrine Semiconductor Corp., founder of RF SOI (silicon on insulator) and pioneer of advanced RF solutions, announces that it has been awarded qualified manufacturers list (QML) certification, class Q (military) and V (space). After a thorough evaluation, Peregrine demonstrated to the Defense Logistics Agency (DLA) Land and Maritime that it fully complies with MIL-PRF-38535, the performance specification used by the Department of Defense for monolithic integrated circuits that operate in severe environments.