1. Why AM Radio Is Hard to Hear Inside Buildings
Have you ever noticed static or noise when listening to AM radio inside a concrete building? The Ministry of Internal Affairs and Communications explains that this happens for several reasons. First, buildings block AM radio waves. Second, the steel and concrete in walls weaken the signal inside. Third, electronic devices create electrical noise that interferes with the signal.[2]
This problem is known in Japan as "urban-type hearing loss." In contrast, FM radio waves tend to reach inside buildings more easily. They are also less affected by electrical noise.[5] The idea was simple: if AM programs were also broadcast on FM, the listening experience might improve. However, how well you hear the radio still depends on your specific location and equipment.
While fixing reception was important, it was only half the reason for starting Wide FM. The other major trigger was the 2011 earthquake.
2. What the Great East Japan Earthquake Showed About Radio Stations
During the Great East Japan Earthquake, people realized again that radio is a vital source of information during disasters. At the same time, a challenge emerged: how to protect AM (medium wave) transmitters, often located in low-lying areas or near water, from tsunamis.[3]
AM antennas require large plots of land, which is why they are often found near rivers or coasts. FM antennas, however, can be placed on mountains or tall towers. This means FM stations are less likely to suffer equipment damage from tsunamis compared to AM stations in low areas.[5]
After the earthquake, a committee recommended using FM waves to support AM broadcasting as a way to prepare for tsunamis.[3] It is important to note that this did not mean all AM stations stopped working during the quake. It was a plan to make the radio network stronger for the future.
If FM was the solution, where could these new FM signals go?
3. How Old TV Channel Frequencies Became Space for Wide FM
Radio waves are divided into frequency bands, and each band has a specific use. Before Wide FM, standard FM broadcasting used the range of 76 to 90MHz. Part of the band beyond that was used by analog terrestrial television. When analog TV ended, part of this band became empty.[4]
The Ministry of Internal Affairs and Communications assigned a part of this empty band (originally 90 to 95MHz) for the purpose of fixing urban reception issues and disaster preparedness.[4] In 2013, discussions began, and in fiscal year 2014, these new stations were officially established as "FM supplementary relay stations."[1][4]
So, Wide FM was created because three conditions aligned: the need to fix poor reception, the lessons from the earthquake, and the availability of empty frequencies. But there was a catch for listeners.
4. Why Some Old Radios Cannot Receive Wide FM
To listen to Wide FM, you need a radio that supports frequencies of 90.1MHz or higher. Older radios that stop at 90.0MHz are not compatible.[7]
This is likely because those radios were designed when FM only went up to 90MHz. You can check if your radio supports Wide FM by looking at the highest number on the frequency scale.
If you use a compatible radio, FM stereo broadcasts are said to have clear sound with little noise. Reception inside buildings and apartments may also be easier.[7]
5. When and Where Wide FM Broadcasting Began
In the Tokai region, CBC Radio (93.7MHz) and Tokai Radio (92.9MHz) started their FM supplementary relay broadcasts on October 1, 2015.[6]
In Tokyo, TBS Radio, Nippon Broadcasting System, and Nippon Cultural Broadcasting started on December 7, 2015. These three stations share an antenna on the Tokyo Skytree.[4]
The content broadcast on Wide FM is the same as the AM radio programs. It is not a new channel with new shows; it is a simultaneous broadcast.[1]
Radio stations also had business reasons for this change. As advertising revenue for radio decreased, Wide FM was hoped to be a way to change that trend.[4]
6. What AM Radio Stations Plan to Do Next
In 2021, 44 commercial AM radio companies, including TBS Radio, Nippon Broadcasting System, and Nippon Cultural Broadcasting, announced a goal. They aim to convert to FM stations by the autumn of 2028.[5]
This plan relies on the fact that many commercial AM stations are already using Wide FM. However, this is a goal, not a final decision. It does not mean AM radio will definitely disappear.
7. How to Check Whether Your Radio Supports Wide FM
If you have a radio at home, look at the FM frequency scale. If the maximum number is around 90MHz, your radio might not support Wide FM.
If you have a radio that receives both AM and FM, and you are in a concrete building, try listening to the same program on both bands. Write down the amount of noise and how clear the sound is. However, remember that radio conditions change depending on the location and time, so do not make a final judgment based on just one test.
For more information, you can read the purpose of the system on the Ministry of Internal Affairs and Communications page.[1] The details about the 2015 launch are also available in their press materials.[6]