RF Fundamentals

Which of the following is true about VSWR? Choose all that apply.

1)To prevent VSWR in a circuit, use impedance-matched cables and connectors 2) A possible effect VSWR can have on RF circuits is damaged transmitter circuits. 3)VSWR is the result of an impedance mismatch in an RF circuit.

What unit of measurement is used to express the gain of an antenna?

Decibels over, or under 1 milliwatt (mW).

What is Equivalent Isotropically Radiated Power (EIRP)?

The power actually radiated by the antenna element.

T/F: Absorption occurs when an RF signal strikes an object and is absorbed into the material of the object in such a manner that it does not pass through, reflect off, or bend around the object.

True

T/F: The bending of a radio wave as it passes through a medium of different density is called refraction.

True

In what manner do radio waves propagate (move) away from the source (antenna)?

In a straight line in all directions at once.

T/F: Reflection occurs when a propagating electromagnetic wave impinges upon an object that has very large dimensions compared to the wavelength of the propagating wave.

True

T/F: The term used to describe an increase in an RF signal's amplitude is called gain

True

T/F: When the medium that a wave travels through consists of objects that have dimensions smaller to those of the wavelength of the signal and the number of obstacles per unit volume is large, scattering occurs.

True

Which of the provided voltage standing wave ratios (VSWR) shown here is best for transferring radio frequency (RF) energy between connections?

1.2:1

Given an access point (AP) with 100 milliwatts (mW) of output power connected through a cable with 3 decibels (dB) of loss to the antenna with a 10 decibels isotropic (dBi) gain, what is the approximate Equivalent Isotropically Radiated Power (EIRP) level from the antenna in mW?

500 mW.

A transmitter outputs 100 milliwatts (mW). An antenna cable connects the transmitter to an amplifier, and the power into the amplifier's input measures 50 mW. The amplifier increases the signal to the original transmitter's power level and sends the signal to the antenna. The antenna receives the signal from the amplifier at 75 mW, and then transmits at 150 mW. What is the intentional radiator's (IR) power level in this radio frequency (RF) circuit?

75 mW.

How does radio frequency line-of-sight (RF LOS) differ from visual LOS?

LOS is accompanied by a Fresnel Zone, a series of concentric ellipsoid-shaped areas around the visual LOS path.

Why is the Fresnel zone important to the integrity of the radio frequency (RF) link or path?

The Fresnel Zone defines an area around the RF line-of-sight (RF LOS) that can introduce RF signal interference if blocked.

What are some measures that can be taken to prevent high voltage standing wave ratios (VSWR) in transmitters and receivers?

Tighten connections between cables and connectors and use impedance-matched hardware throughout.