XPost: rec.radio.amateur.moderated

KB6NU's Ham Radio Blog

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Funny stuff from /r/amateurradio

Posted: 19 Jan 2022 07:54 AM PST https://www.kb6nu.com/funny-stuff-from-r-amateurradio/?utm_source=feedburner&utm_medium=email


One of the reasons I like the subreddit /r/amateurradio are the funny
things that are posted to it. Here are three of the latest.

This was posted with the headline, Those ReCaptchas are getting out of
hand ;-).



I thought this one was really funny, too.



Im not a Baofeng hater, but you gotta admit this is amusing.

Need to hoist an antenna? Most hams lack this simple tool from
HamRadio



The post Funny stuff from /r/amateurradio appeared first on KB6NUs Ham
Radio Blog.


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2022 No Nonsense Technician Class License Study Guide: Radio wave characteristics

Posted: 18 Jan 2022 06:54 PM PST https://www.kb6nu.com/2022-no-nonsense-technician-class-license-study-guide-radio-wave-characteristics/?utm_source=feedburner&utm_medium=email


Heres the third chapter from the 2022 version of the No Nonsense Technician Class License Study Guide.Dan

Frequency, wavelength, and the electromagnetic spectrum

Radio waves are what amateur radio is all about. Amateur radio operators generate them and send them off into space. Then, we capture them and demodulate them.

Radio waves are also called electromagnetic waves because they consist of
both an electric field and a magnetic field. The two fields are at right
angles to one another as they travel through space.

T3B03

What are the two components of a radio wave?

A. Impedance and reactance

B. Voltage and current

C. Electric and magnetic fields

D. Ionizing and non-ionizing radiation

T3B01

What is the relationship between the electric and magnetic fields of an electromagnetic wave?

A. They travel at different speeds

B. They are in parallel

C. They revolve in opposite directions

D. They are at right angles
All electromagnetic waves, including radio waves, travel at the speed of
light, or 300 million meters per second.

T3B04

What is the velocity of a radio wave traveling through free space?

A. Speed of light

B. Speed of sound

C. Speed inversely proportional to its wavelength

D. Speed that increases as the frequency increases

T3B11

What is the approximate velocity of a radio wave in free space?

A. 150,000 meters per second

B. 300,000,000 meters per second

C. 300,000,000 miles per hour

D. 150,000 miles per hour

An important characteristic of a radio wave is its frequency, or the number
of cycles per second. As mentioned earlier, the unit of frequency is the
Hertz. We abbreviate Hertz as Hz, and one Hz is one cycle per second.

A characteristic of a radio wave that is related to frequency is its wavelength. A wavelength is the distance that a radio wave travels during
one cycle. Because radio waves travel at the speed of light, or 300,000,000 meters per second, the wavelength is 300,000,000 divided by the frequency.
To make this easier to calculate, you can divide both the speed of light
and the frequency by one million. That makes the equation:

wavelength (m) = 300/f (MHz)
The converse of this equation is:

f (MHz) = 300/wavelength (m)
As you can see from the equations, the lower the frequency, the longer the wavelength, and vice versa, the higher the frequency, the shorter the wavelength.

T3B06

What is the formula for converting frequency to approximate wavelength in meters?

A. Wavelength in meters equals frequency in hertz multiplied by 300

B. Wavelength in meters equals frequency in hertz divided by 300

C. Wavelength in meters equals frequency in megahertz divided by 300

D. Wavelength in meters equals 300 divided by frequency in megahertz

T3B05

What is the relationship between wavelength and frequency?

A. Wavelength gets longer as frequency increases

B. Wavelength gets shorter as frequency increases

C. Wavelength and frequency are unrelated

D. Wavelength and frequency increase as path length increases
In amateur radio, we sometimes use the frequency and sometimes the
wavelength when talking about a radio signal. We use wavelength, for
example, when we refer to the amateur radio bands. The 2 m amateur radio
band, for example, spans 144 MHz to 148 MHz. A radio wave with a frequency
of 148 MHz, would have a wavelength of 2.03 meters.

T3B07

In addition to frequency, which of the following is used to identify
amateur radio bands?

A. The approximate wavelength in meters

B. Traditional letter/number designators

C. Channel numbers

D. All these choices are correct
For convenience, we split the entire range of radio frequencies into sub-ranges, including high frequency (HF), very high frequency (VHF), and
ultra high frequency (UHF).

T3B10

What frequency range is referred to as HF?

A. 300 to 3000 MHz

B. 30 to 300 MHz

C. 3 to 30 MHz

D. 300 to 3000 kHz

T3B08

What frequency range is referred to as VHF?

A. 30 kHz to 300 kHz

B. 30 MHz to 300 MHz

C. 300 kHz to 3000 kHz

D. 300 MHz to 3000 MHz

T3B09

What frequency range is referred to as UHF?

A. 30 to 300 kHz

B. 30 to 300 MHz

C. 300 to 3000 kHz

D. 300 to 3000 MHz
A radio signal of any frequency is called a radio frequency, or RF, signal.

T5C06

What does the abbreviation “RF” mean?

A. Radio frequency signals of all types

B. The resonant frequency of a tuned circuit

C. The real frequency transmitted as opposed to the apparent frequency

D. Reflective force in antenna transmission lines
Properties of radio waves and propagation modes
As amateur radio operators, we should always try to use the right frequency
and the right mode when communicating. To do this, we need to know how
radio signals travel from one point to another and what effect frequency,
our antennas and even our location have on signal propagation.
Communications at VHF and UHF frequencies are generally “line-of-sight” communications. This means they normally travel in a straight line from the transmitter to the receiver. For this reason, they are normally used for
local communications.
Because VHF and UHF signals are line-of-sight, at some distance, the
signals will be blocked by the curvature of the Earth. The maximum distance
for line-of-sight communications is called the radio horizon. The radio
horizon extends somewhat farther than the visual horizon.

T3C11

Why is the radio horizon for VHF and UHF signals more distant than the
visual horizon?

A. Radio signals move somewhat faster than the speed of light

B. Radio waves are not blocked by dust particles

C. The atmosphere refracts radio waves slightly

D. Radio waves are blocked by dust particles

T3C01

Why are simplex UHF signals rarely heard beyond their radio horizon?

A. They are too weak to go very far

B. FCC regulations prohibit them from going more than 50 miles

C. UHF signals are usually not propagated by the ionosphere

D. UHF signals are absorbed by the ionospheric D region
Some signals bounce off the ionosphere. This gives them the ability to
travel much further than line of sight. We’ll talk more about the
ionosphere later.


One problem often encountered when using VHF and UHF frequencies is
multipath propagation. Multipath propagation occurs when your signals
arrive at a receiving station via two or more paths. Since the signal paths
may be different lengths, the signals may arrive out of phase and cancel
one another or arrive in phase and reinforce one another. Moving an antenna only a few feet, say when you’re operating mobile, can cause the received signal strength to vary greatly.

T3A01

Why do VHF signal strengths sometimes vary greatly when the antenna is
moved only a few feet?

A. The signal path encounters different concentrations of water vapor

B. VHF ionospheric propagation is very sensitive to path length

C. Multipath propagation cancels or reinforces signals

D. All these choices are correct
This can be a real problem for mobile operation, as your transmitter and antenna location is constantly changing. This means that the signal
strength at the receiving station constantly changes as well. This rapid fluctuation in received signal strength is sometimes called picket fencing.

T3A06

What is the meaning of the term “picket fencing”?

A. Alternating transmissions during a net operation

B. Rapid flutter on mobile signals due to multipath propagation

C. A type of ground system used with vertical antennas

D. Local vs long-distance communications
Because it can cause signal strength to vary greatly, multipath propagation affects both voice and digital transmissions. Since reliable digital transmissions rely on the signals being relatively constant and strong, multipath propagation can cause errors to occur.

T3A10

What effect does multipath propagation have on data transmissions?

A. Transmission rates must be increased by a factor equal to the number of separate paths observed

B. Transmission rates must be decreased by a factor equal to the number of separate paths observed

C. No significant changes will occur if the signals are transmitted using FM

D. Error rates are likely to increase


Knowing how VHF and UHF signals propagate can help you communicate even in adverse conditions. When trying to use a repeater, for example, you may
find yourself in a place where a direct path to the repeater is not
possible. If you find yourself in this situation, you could try using a directional antenna and bounce your signal off buildings or other
obstructions.

T3A05

When using a directional antenna, how might your station be able to
communicate with a distant repeater if buildings or obstructions are
blocking the direct line of sight path?

A. Change from vertical to horizontal polarization

B. Try to find a path that reflects signals to the repeater

C. Try the long path

D. Increase the antenna SWR
Another phenomenon you might use when a direct path to a repeater is not possible is “knife-edge” diffraction. You might be able to use this phenomenon to get your signal around a building in an urban setting or over
a mountain peak in an outside setting.

T3C05

Which of the following effects may allow radio signals to travel beyond obstructions between the transmitting and receiving stations?

A. Knife-edge diffraction

B. Faraday rotation

C. Quantum tunneling

D. Doppler shift
A condition that could impede the transmission of UHF and microwave signals
is heavy vegetation. So, keep your antennas out of trees or above trees.

T3A02

What is the effect of vegetation on UHF and microwave signals?

A. Knife-edge diffraction

B. Absorption

C. Amplification

D. Polarization rotation


Antenna polarization is important at VHF and UHF frequencies. How you mount
an antenna directly affects its polarization. When the radiating element of
an antenna is vertical, the transmitted radio waves will have a vertical polarization. When the radiating element of an antenna is horizontal, the
radio waves will have a horizontal polarization.

T3B02

What property of a radio wave defines its polarization?

A. The orientation of the electric field

B. The orientation of the magnetic field

C. The ratio of the energy in the magnetic field to the energy in the
electric field

D. The ratio of the velocity to the wavelength

T3A04

What happens when antennas at opposite ends of a VHF or UHF line of sight
radio link are not using the same polarization?

A. The modulation sidebands might become inverted

B. Received signal strength is reduced

C. Signals have an echo effect

D. Nothing significant will happen
When using a repeater, vertical polarization is most often used. So, when
using a handheld transceiver, make sure to hold it so that your antenna is straight up and down. Different activities use different antenna
polarizations, though.

T3A03

What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?

A. Right-hand circular

B. Left-hand circular

C. Horizontal

D. Vertical
The reason for this is that operators transmitting CW and SSB signals are
often using what are called beam antennas, and it’s much easier to mount
and operate beam antennas horizontally than it is to mount them vertically.


Even though VHF communications are most often line-of-sight, there are some propagation modes that make it possible to communicate over long distances.
For example, sometimes VHF signals will bounce off the E layer of the ionosphere. This phenomenon is called “sporadic E” propagation because it happens only sporadically.

T3C04

Which of the following types of propagation is most commonly associated
with occasional strong signals on the 10, 6, and 2 meter bands from beyond
the radio horizon?

A. Backscatter

B. Sporadic E

C. D region absorption

D. Gray-line propagation
Other interesting propagation phenomena at VHF frequencies include auroral backscatter, meteor scatter, tropospheric scatter, and tropospheric
ducting. Bouncing signals off the earth’s aurora is very interesting to do, but the signals usually become distorted and signal strength can vary
greatly. This is because the aurora itself is constantly changing.

T3C03

What is a characteristic of VHF signals received via auroral backscatter?

A. They are often received from 10,000 miles or more

B. They are distorted and signal strength varies considerably

C. They occur only during winter nighttime hours

D. They are generally strongest when your antenna is aimed west
Some hams also bounce signals off meteor showers. This propagation mode is called meteor scatter. Meteor scatter propagation is most pronounced on the 6-meter band.

T3C07

What band is best suited for communicating via meteor scatter?

A. 33 centimeters

B. 6 meters

C. 2 meters

D. 70 centimeters
One question that I often get is whether or not the weather affects radio
wave propagation. The short answer is no, but there are, of course,
exceptions to this rule. One way that weather can affect radio propagation
is when there is a temperature inversion in the atmosphere. A temperature inversion occurs when a layer of cooler air gets trapped below a layer of warmer air in the troposphere. The troposphere is the lowest region of the atmosphere, extending from the earth’s surface to a height of about 6–10 km..
When this happens, a tropospheric duct may form. VHF signals entering this
duct may propagate through the duct for hundreds of miles.

T3C06

What type of propagation is responsible for allowing over-the-horizon VHF
and UHF communications to ranges of approximately 300 miles on a regular
basis?

A. Tropospheric ducting

B. D region refraction

C. F2 region refraction

D. Faraday rotation

T3C08

What causes tropospheric ducting?

A. Discharges of lightning during electrical storms

B. Sunspots and solar flares

C. Updrafts from hurricanes and tornadoes

D. Temperature inversions in the atmosphere
Another exception to the rule occurs at microwave frequencies.
Precipitation, including rain, snow, or ice can absorb microwave signals, thereby decreasing range. At lower frequencies, however, precipitation has little or no effect on propagation.

T3A07

What weather condition might decrease range at microwave frequencies?

A. High winds

B. Low barometric pressure

C. Precipitation

D. Colder temperatures

T3A12

What is the effect of fog and rain on signals in the 10 meter and 6 meter bands?

A. Absorption

B. There is little effect

C. Deflection

D. Range increase


The post 2022 No Nonsense Technician Class License Study Guide: Radio wave characteristics appeared first on KB6NUs Ham Radio Blog.

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