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We iron out the confusion – Radio Fidelity

    Radios use radio waves to transmit acoustic messages and information for communication. These waves are classified as either long or short, resulting in longwave and shortwave radios. Because of how they work, there is confusion between longwave and shortwave radio. What’s the difference and how do they work?

    A long wave radio tunes to long wave radio signals with low frequencies between 30 and 279 kHz. On the other hand, shortwave radios tune to higher frequency shortwave radio signals in the range between 3 and 30 MHz (3,000 and 30,000 kHz).

    In the rest of this article, I will discuss longwave and shortwave radios to clear any confusion. I’ll also talk about longwave and shortwave to help you understand the main differences.

    Let’s begin!

    What is a longwave vs shortwave radio?

    A long wave radio is a radio transmission technology that operates on frequencies between 30 and 279 kHz. It is mainly used for straight line communication as these waves can maneuver obstacles.

    Long waves follow the contours of the earth or travel beyond the horizon to reach the target receiver.

    The long wavelength means these radios have coverage a greater distance in a single transmission. Therefore, they can travel several kilometers from the transmitting antenna to the receiving antenna.

    In contrast, shortwave radio is a broadcasting technology that operates on shortwave and higher frequencies in the range between 3 and 30 MHz (3,000 and 30,000 kHz).

    It is mainly used for International communication over longer distances.

    In contrast to long-wave radios, short-wave radios are based on the principle of reflected signals from the Earth’s ionosphere before it reaches the recipient.

    Black shortwave radio on a table with a red band around the antenna
    A shortwave radio can transmit radio waves over long distances because of its receiving antenna.

    Because the ionosphere contains a high proportion of free electrons, it vibrates and re-emits the shortwave signals back to Earth at the same frequency.

    Shortwave radio broadcasts can travel several thousand miles from the transmitting point to the receiving antenna due to the radiative effect of the ionosphere. This makes shortwave broadcasting ideal for:

    ● International News

    ● Mobile phone communication

    ● Maritime communication

    ● Ham Radio

    What is the difference between shortwave and longwave?

    The difference between shortwave and longwave is theirs Frequency ranges in the electromagnetic spectrum.

    While shortwave has higher frequencies, between 3,000 and 30,000 kHz, longwave has lower frequencies, less than 300 kHz.

    The best way to distinguish between short and long waves is to look at the Relationship between frequency and wavelength of a wave.

    According to the Center for Science Education, frequency and wavelength are inversely proportional.

    Therefore, short waves have shorter wavelengths and higher frequencies, while long waves have longer wavelengths and lower frequencies.

    What about Range between shortwave and longwave? Which bridges greater distances? The answer to this question depends on the wavelength definition of a wave.

    Northwestern University states that the wavelength of a wave is the distance between two consecutive wave crests.

    Therefore, long waves have a larger inter-ridge spacing, while short waves have shorter inter-ridge spacings, as shown below.

    Comparison of longwave and shortwave

    Old: Shorter and longer wavelengths. Source: Northwest University

    The greater the distance between two consecutive wave crests, the greater the distance traveled and the farther it can be traveled in a single transmission.

    This explains why longwave radio transmissions can cover longer distances in a single transmission.

    However, long waves are unsuitable for international communication because they can only be transmitted over straight lines.

    Therefore, they have to overcome obstacles such as tall buildings or mountains, which consumes a lot of energy.

    Shortwave radio is a better option for international communication because it bounces off the Earth’s ionosphere before reaching the receiver.

    Long Wave vs Short Wave: How Do They Work?

    Longwave and shortwave radios operate on the following principles.

    Transmission: A transmitter at one end modulates or encodes messages. It does this by varying the frequency or amplitude of the waves, much like Morse code.

    Reception: A recipient at the other end receives and decodes the message into the desired form such as image, data or sound. In order for the decoding process to take place, the receiver must be tuned to the same frequency as the transmitter.

    Although these radios operate on the basic principles outlined above, they route their signals differently.

    Long waves travel in a straight line and risk hitting obstacles and losing momentum.

    However, although these waves travel in straight lines, they can maneuver through barriers to get to the receiver.

    For example, they can walk over the horizon or follow the contours of the earth to reach their destination.

    Short waves, on the other hand, spread reflection from the ionosphere. The transmitter directs the short waves at an angle to the ionosphere for reflection.

    As soon as they hit the ionosphere, they are reflected back to the receiver, overcoming the horizon obstacle.

    Consequently, shortwave bridges greater distances and is therefore ideal for long-distance and international communication.

    Why are long wave radios used in maritime communications?

    Long-wave radios are used in maritime communications because they excel at sending long-distance signals at low power. The power requirement makes them energy efficient and ideal for ships communicating with inland supply stations.

    In addition, long wave radios can maneuver obstacles to reach their destination, making them suitable for sea navigation.

    The table below compares longwave and shortwave radio.

    reference point longwave radio shortwave radio
    type of signal Tune to longwave signals Tune to shortwave signals
    Purpose Daily reception of signals distant communication
    How signals travel On a straight path Reflection from the ionosphere
    best for community radio station Shortwave broadcasters and areas where some broadcasts are prohibited. They are also suitable for emergencies
    popularity Moderately popular around the world Popular in the 20thth Century. It also gained popularity in 2020 during the Covid-19 pandemic lockdown
    frequency Lower frequency due to the longer wavelengths Higher frequency due to the shorter wavelengths

    Table 1: Comparison of longwave and shortwave radio


    Longwave and shortwave radio are broadcasting technologies with different operational characteristics.

    Although long waves travel in a straight path, they can maneuver through obstacles to reach the receiver.

    Shortwave radios work by bouncing signals off the earth’s ionosphere to get to the receiver.

    Hopefully that clears things up!