answersLogoWhite

0

Orthomode transducer

From Wikipedia, the free encyclopedia

Orthomode transducer, VSAT Kuband

Outdoor unit, includes feed horn, OMT, LNB and BUC

Orthomode transducer (Portenseigne, France)

Orthomode transducer, vertical and horizontal polarity

Antenna side of OMT

An orthomode transducer is a microwave duct component of the class of microwave circulators. It is commonly referred to as an OMT, and commonly referred as a polarisation duplexer. Such device may be part of a VSAT antenna feed Orthomode transducers serve either to combine or to separate two microwave signal paths. One of the paths forms the uplink, which is transmitted over the same waveguide as the received signal path, or downlink path. For VSAT modems the transmission and reception paths are at 90° to each other, or in other words, the signals are orthogonally polarised with respect to each other. This orthogonal shift between the two signal paths provides approximately an isolation of 40dB in the Ku band and Ka band radio frequency bands.

Hence this device serves in an essential role as the junction element of the outdoor, unit (ODU) of a VSAT modem. It protects the receiver front-end element (thelow-noise block converter, LNB) from burn-out by the power of the output signal generated by the block up converter (BUC). The BUC is also connected to thefeed horn through a wave guide port of the OMT junction device.

Orthomode transducers are used in dual-polarised Very small aperture terminals (VSATs), in sparsely populated areas, radar antennas, radiometers, and communications links. They are usually connected to the antenna's down converter or LNB and to the High Power Amplifier (HPA) attached to a transmittingantenna.

Wherever there are two polarisations of radio signals (Horizontal and Vertical), the transmitted and received radio signal to and fro the antenna are said to be "orthogonal". This means that the modulation planes of the two radio signal waves are at 90 degrees angles to each other. The OMT device is used to separate two equal frequency signals, of high and low signal power. Protective separation is essential as the transmitter unit would seriously damage the very sensitive low (µV) micro-voltage, front-end receiver amplifier unit at the antenna.

The transmission signal of the up-link, of relatively high power (1, 2,or 5 watts for common VSAT equipment) originating from BUC,(block up converter) and the very low power received signal power (µ-volts) coming from the antenna (aerial) to the LNB receiver unit, in this case are at an angle of 90° relative to each other, are both coupled together at the feed-horn focal-point of the Parabolic antenna. The device that unites both up-link and down-link paths, which are at 90° to each other, is known as an Orthogonal Mode Transducer OMT.

In the VSAT Ku band of operation case, a typical OMTOrthomode Transducer provides a 40dB isolation between each of the connected radio ports to the feed horn that faces the parabolic dish reflector (40dB means that only 0.01% of the transmitter's output power is cross-fed into the receiver's wave guide port). The port facing the parabolic reflector of the antenna is a circular polarizing port so that horizontal and vertical polarity coupling of inbound and outbound radio signal is easily achieved.

The 40dB isolation provides essential protection to the very sensitive receiver amplifier against burn out from the relatively high-power signal of the transmitter unit. Further isolation may be obtained by means of selective radio frequency filtering to achieve an isolation of 100dB (100dB means that only a 10−10 fraction of the transmitter's output power is cross-fed into the wave guide port of the receiver).

The second image demonstrates two types of outdoor units, a 1-watt Hughes unit and a composite configuration of a 2-watt BUC/OMT/LNB Andrew, Swedish Microwave units.

The following images show a Portenseigne & HirschmannKu band configuration, that highlights the horizontal the vertical, and circular polarized wave-guide ports that join to the Feed-horn, the LNB or BUC elements of an outdoor unit

User Avatar

Wiki User

14y ago

What else can I help you with?

Continue Learning about Movies & Television

How does 3Dimensional glasses work?

There are two types of 3-D glasses: 1) Different colored lenses. An image containing both colors is projected at your face, but the tint of each lens filters out one of the colors (the red lens prevents you from seeing the red image, while the blue lens prevents you from seeing the blue image), resulting in each eye seeing a slightly different image. This difference is the basis for depth perception and binocular vision. Your brain combines the two images, fooling itself into thinking the images have depth. 2) Polarization. If you have ever had polarized sunglasses, you know the effect. Imagine the polarized lens as a picket fence and light waves as pieces of wood that fit between the slats. The only wood pieces (light photons) that make it through the fence (the lens) are the ones oriented in the same direction as the slats in the fence. All other wood pieces (light waves) are filtered out. In this method, the two images are pre-polarized by a filter on the projector, which results each image consisting of only one wave form (it's convenient to thing of these wave forms as vertical and horizontal). On the glasses themselves, one lens is polarized vertically and the other horizontally, so the only the vertically polarized image goes through the vertical lens, and only the horizontally polarized image goes through the horizontal lens, again resulting in your brain seeing a slightly different image in each eye, which causes the illusion of depth.


Can a non polarized capacitor be connected to a direct current circuit?

Yes, you can connect a polarized capacitor to a direct current. Make sure you get your polarization is correct.A non polarized capacitor can be connected in a DC circuit as well. "Non Polarized" just means it does not matter which side of the capacitor is positive. If you attempt to connect a polarized capacitor in a DC circuit backwards, you will know when the capacitor explodes.


Can you watch 3D polarized movies on your laptop?

depends on your LCD


What is an unpolarized capacitor?

A capacitor that does not have a designated + and - side. Electrolytic capacitors are usually polarized. Ceramic capacitors are not.


What the function of polarized electrolytic capacitor?

Electrolytic capacitors are used for power filter, decoupling, signal coupling and time constant setting, DC blocking, etc. Polarized electrolytic capacitors usually play a role in power supply circuits or intermediate frequency and low frequency circuits for power supply filtering, decoupling, signal coupling, time constant setting, and DC blocking. Generally electrolytic capacitors cannot be used in AC power circuits. When used as filter capacitors in DC power circuits, its anode (positive) should be connected to the positive terminal of the power supply voltage, and the cathode (negative) should be connected to the negative terminal of the power supply voltage. Otherwise it will damage the capacitor. We're JYH HSU(JEC) Electronics Ltd (or Dongguan Zhixu Electronic Co., Ltd.), an electronic components manufacturer. You may google search "JYH HSU" to find our official website.

Related Questions

Do sunglasses polarize light vertically?

Yes, polarized sunglasses typically block horizontally polarized light while allowing vertically polarized light to pass through. This helps to reduce glare from reflective surfaces such as water or snow.


Is a wave length horizontal or vertical?

If you can visualize whipping a length of rope tied to a fixed spot back and forth, you can then perfectly visualize radio frequency waves. If you whip the rope up and down the wave is vertically polarized. If you whip it back and forth horizontally, it is horizontally polarized. If you use a set of "rabbit ears" (dipole) to transmit a signal and hold it so the antenna points up and down, the radiated waves will be vertically polarized. To receive vertically polarized waves best, you need to use a vertically polarized antenna. The same holds true for horizontally polarized systems. This is a very simple but applicable explanation. There are other kinds of polarization such as "circular" as used in FM broadcasting and space communications. Just remember that the transmitting antenna's design determines the polarization of a radiated wave. See the ARRL Handbook 621.384 in your library for more detail.


What are the advantages of using vertically polarized antennas in wireless communication systems?

Vertically polarized antennas offer better signal propagation in urban environments with tall buildings and obstacles, as the signal can penetrate through obstacles more effectively. They also help reduce interference from horizontally polarized signals, resulting in improved signal quality and reliability in wireless communication systems.


Why can you not use electromagnetic waves in water?

Because the electric field portion of the electromagnetic wave are rapidly attenuated in water, due to its conductivity. This is also why light becomes horizontally polarized when it reflects off water, the vertically polarized part of the electric field is absorbed during the process of reflection.


Which direction is the axis of polarization in a pair of polarized sunglasses?

The axis of polarization in a pair of polarized sunglasses is oriented to block horizontally polarized light. This means that the lenses are designed to allow vertically polarized light to pass through while reducing glare from surfaces like water or roads, which often reflect horizontal light. The specific orientation helps improve visibility and reduce eye strain in bright conditions.


What is plane polarized of light?

That's the simplest kind of polarization, and it simply means that all pieces of light - all photons - have the same orientation in space. For example, if the light shines horizontally, the light can be vertically polarized, or it may be horizontally polarized. Or at some other angle in between.


Light reflected from water is strongly polarized in the horizontal direction How would you design sunglasses for a ship pilot who needs to see objects on the water surface?

To reduce glare from horizontally polarized light reflected off water, sunglasses with vertical polarization filters can be used. These filters will block the horizontally polarized light waves, allowing the ship pilot to see objects on the water surface more clearly without the glare. It's important to ensure that the sunglasses provide UV protection as well for overall eye safety.


When sunlight reflects from a horizontal surface horizontally polarized light reflects more strongly than the rest of the sunlight. This reflection produces .?

This reflection produces glare, which can be uncomfortable and can affect visibility, especially when driving or near water. Using polarized sunglasses can help reduce this glare by filtering out horizontally polarized light.


If your driving towards the sun late in the afternoon you can reduce the glare from the road by wearing sunglasses that permit only the passage of the light that is?

polarized horizontally, as this type of polarization helps to block the horizontally polarized light that causes glare from reflecting off flat surfaces like roads. This can improve visibility and reduce squinting caused by intense sunlight.


What Happens When an AC of 5A and dc current of 5A flow simultaneously through a circuit?

it will be the polarized sum of the two quantity


In what direction is the polarization of the glare that reflects from a horizontal surface?

The glare that reflects from a horizontal surface is horizontally polarized, meaning the light waves are mostly oscillating in a horizontal plane. This polarization causes the glare to be more intense when viewed horizontally.


Polarized sunglasses work by?

When light reflects off flat surfaces, such as pavement or water, it becomes polarized. This means that instead of scattering in all directions, it travels horizontally. Humans experience polarized light as glare. Polarized sunglasses block polarized light with vertical filters that prevent horizontal light from passing through. Only light traveling vertically can pass through the vertical filter.