ESAT RHM2 Part3 201 to 300

Is the process of adjusting the position of a directional antenna on the ground.

It is an orbit which rotates in the same direction as Earth's rotation (counterclockwise, west to east) and having an angular velocity greater than the Earth

Find the orbital period of a satellite in a circular orbit 500 km above the earth's surface

Is a private telephone system for larger organizations which is located at the subscriber and connected to the telephone network.

It is a type of signaling wherein the frequencies that are used for the signaling pulse fall outside the range of the information.

It is a type of signaling wherein there is a dedicated line for each for the signaling and voice information.

A ____ wave whose surfaces of constant phase are infinite parallel planes normal to the direction of propagation.

The reason why only a finite number of modes can propagate along the fiber.

It is the apparent height of the ionized layer and it is measured by sending a wave vertically to the layer.

A ____ wave whose surfaces of constant phase are infinite parallel planes normal to the direction of propagation.

It is the most common type of fading caused by mixing of two or more signal components propagating along different paths.

It is caused by solar flare activities and particularly affects the lower frequencies.

Calculate the power gain and bandwidth of a microwave dish antenna with a 3m mouth diameter when used at 10 GHz.

All communication frequencies throughout the spectrum are affected in varying degrees by the:

The ability of the ionosphere to reflect high frequency radio signals depends on:

What happens to signals higher in frequency than the critical frequency?

Irregular cloud-like patches of unusually high ionization. Often forms at heights near the normal E layer.

A pyramidal horn has an aperture (opening) of 58 mm in the E plane and 78 mm in the H plane. It operates at 10 GHz. Calculate its gain in dBi.

An irregular ionospheric disturbance that can totally blank out hf radio communications.

A type of substance, such as frosted glass, through which some light rays can pass but through which objects cannot be seen clearly.

The first person to produce circular polarization (circularly polarized light).

It is the surface containing every point for which the sum of the distance from that point to the two ends of the path is exactly half wavelength longer than the direct path.

Is a path wherein the microwave beam barely touches the obstruction.

It is the vertical angle formed between the direction of travel of electromagnetic wave radiated from an Earth station antenna.

It is the geographical representation of a satellite antenna's radiation pattern.

A category of footprint that covers 20% of Earth's surface.

It is caused by excessive pressure and tension and generally occur when fibers are bent during handling or installation.

It is a PN junction diode that is usually made up of aluminum gallium arsenide or gallium arsenide phosphide.

It is a depletion layer photodiode and is probably the most common device used as a light detector in fiber optic communications system.

Numerical aperture is used to define the ______ of an optical fiber.

Mode theory is used to describe the _______ of plane waves able to propagate along an optical fiber.

Skew rays tend to propagate near the edge of the fiber core. A large portion of the number of skew rays that are trapped in the fiber core are considered to be ________

It is also known as direct wave propagation or line-of-sight propagation, and it is the propagation mode wherein the radio waves leave the transmitting antenna and travel in a straight line toward the receiving antenna.

It reduces the signal strength by bending the ray away from the receiving point.

It is also known as ionoscatter, and works much the same as tropospheric scatter, except that the scattering medium is the E region of the ionosphere, with some help of the D and F layers.

What does maximum usable frequency mean?

What is one way to determine if the maximum usable frequency (MUF) is high enough to support 28 MHz propagation between your station and western Europe?

At what point in the solar cycle does the 20-metre band usually support worldwide propagation during daylight hours?

The propagation of radio waves in the troposphere by means of scatter.

Waves radiated with the E field component perpendicular to the earth's surface.

A small section of an expanding sphere of electromagnetic radiation, perpendicular to the direction of travel of the energy.

It is defined by the radiated power by an antenna in its favored direction, taking into account as referenced to the isotropic radiator.

It is the RF signal level impinging on the far end receiver antenna as if it were an isotropic antenna.

It is the most important parameter considered when evaluating the performance of a microwave system. It is a pre- detection (before FM demodulator) signal- to-noise ratio.

A subscriber makes three phone calls of three minutes, four minutes, and two minutes duration in one hour period. Calculate the subscriber traffic in erlangs, CCS, and Cm.

A set of standards established by the ITU for handling call signaling on the PSTN (public switch telephone network).

It allows a subscriber to place domestic long distance calls directly from his own set without the need of operator assistance by dialing special access codes.

The reason why only a finite number of modes can propagate along the fiber.

The change in the propagation constant for different wavelengths is called _________.

Modes traveling in an optical fiber are said to be ________.

It is the range of wavelength values that can be used for a given photodiode.

It is permanently attaching the end of one optical fiber cable to another.

It is the measure of conversion efficiency of a photodetector. It is the ratio of the output current of photodiode to the input optical power.

Are stronger than backscatter signals using the same general area of ground scattering.

The visible aurora fluorescence at E layer height is a curtain of ions capable of refracting radio waves in the frequency range of about 20 MHz.

Consider a space-diversity microwave radio system operating at an RF carrier frequency of 1.8 GHz. Each station has a 2.4-m-diameter parabolic antenna that is fed by 100 m of air-filled coaxial cable. The terrain is smooth, and the area has a humid climate. The distance between stations is 40 km. A reliability objective of 99.99% is desired. Determine the system gain.

A type of communication between two or more points on Earth.

Communication on the 80 metre band is generally most difficult during:

During summer daytime, which bands are the most difficult for communications beyond ground wave?

The distance a disturbance travels during one period of vibration.

Hat effect does tropospheric bending have on 2-metre radio waves?

It is a general term applied to the reduction in signal strength at the input to a receiver.

It is the attenuation allowance so that anticipated fading will still keep the signal above specified minimum RF input.

Defined as the system without built-in redundancy and a function of MTBF (mean time before failure) and MTTR (mean time to repair).

The electric field is perpendicular to the direction of propagation and the magnetic field is in the direction of propagation.

The magnetic field is perpendicular to the direction of propagation.

This penetrate further into the cladding material and the electrical and magnetic fields are distributed more toward the outer edges of the fiber.

Wave that travels directly from transmitter antenna to receiver antenna, reaching only about as far as the horizon.

The curvature of Earth presents a horizon to space wave propagation. This is called:

Another term for sky wave propagation.

That portion of the radiation kept close to the earth's surface due to bending in the atmosphere is called the:

On which amateur frequency band is the extended-distance propagation effect of sporadic-E most often observed?

It suggests that there is more than one transmission path or method of transmission available between a transmitter and a receiver.

Where in the ionosphere does auroral activity occur?

It is more than one receiver for a single radio-frequency channel.

It is a form of hybrid diversity and provides the most reliable transmission but most expensive. It combines frequency, space, polarization, and receiver diversity into one system.

Is a term associated with a table showing the position of a heavenly body on a number sates in a regular sequence.

The body of the satellite remains fixed relative to the Earth's surface while an internal subsystem provides roll and yaw stabilization.

Is a communications path formed between two or more ground station transmitting and receiving radio communications traffic via satellite

It determines how many modes a fiber can support.

Single mode fibers are capable of transferring higher amounts of data due to _____?

What happens as the number of mode increases in multimode fibers?

This is sometimes used to determine the critical frequency.

This is defined as the loss incurred by an electromagnetic wave as it propagated in a straight line through a vacuum with no absorption or reflection of energy from nearby objects.

Excluding enhanced propagation modes, what is the approximate range of normal VHF tropospheric propagation?

What kind of propagation would best be used by two stations within each other's skip zone on a certain frequency?

What is a characteristic of HF scatter signals?

Is the transmitted signal from the Earth station to the satellite.

It is the removal of satellite from service.

It is the loss of optical power as light travels along the fiber.

The portion of attenuation resulting from the conversion of optical power into another energy form, such as heat.

Caused by basic fiber-material properties.

Why are HF scatter signals usually weak?

When does scatter propagation on the HF bands most often occur?

Meteor scatter is most effective on what band?

What is the main cause of intrinsic absorption in the infrared region?

Caused by the electronic transition of these metal ions from one energy level to another.

Occurs when the size of the density fluctuation is less than one-tenth of the operating wavelength of light.

In which frequency range is meteor scatter most effective for extended-range communication?

As frequency decreases, and gain and beamwidth of a parabolic antenna: