What is Radio Meteor Obseration ? (mechanism)
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Radio Meteor Observation uses VHF(30MHz-300MHz) radio wave. A VHF transmitting station is located at a very far distance from observing (receiving) station. It therefore is impossible to receive the direct radio wave from transmitting station at receiving station. When a meteor enters atmosphere, it ionizes atmosphere and separates between free electrons and plus ions. Then the density of electrons increase and an "ionized trail" us produced around there. Free electrons has a principle which is scattering of VHF radio wave. When a meteor appears, therefore, we can receive VHF radio wave from ionized trail at receiving station. The right figure is the image of mechanism of meteor scattering.
Radio Meteor Observation has two observing methods. One is a back scattering and another is a forward scattering. The back scattering has a principle which is that the receiving and transmitting stations are located at same position. It therefore is possible to obtain detail meteor information such as meteor geocentric velocity and beginning and ending height. This observation is also called "Radar Observation". Although this method is useful for analyzing meteor phenomenan, it needs a lot of costs. It therefore is difficult for amateur observers to do. The forward scattering observation is major observation because this method is very easy and simple to start. There are over 150 observing stations in the world. In particular, there are many observing stations in Japan. Although this observation is simple, there are some serious problems. One of them is the charactristic of reflection mechanism. The forward scattering basically satisfys that incident angle is equal to reflection angle. The reflection point changes and depends on the change of radiant elevation. We therefore have to understand charactistics of forward scattering observation well.
Like this , Radio Meteor Observation mainly means the forward scattering. Of course, by using radio wave, it is possible to observe and monitor meteor activity even if in bad weather and at daytime. Then if there is a stable transmitting station, it becomes possible to observe continuously by using computer and observing software. Since observing equipments are not expensive, it is easy to start.
Using frequency type
When you start Radio Meteor Observation, you have to select the transmitting station. There are many VHF radio stations in the world, you have to select the best transmitting stations. Generally, Japanese and Korean observers can use Ham-band radio wave at 53.750MHz (located at Fukui, Japan). In Europe, many observers use TV radio wave and FM broadcast radio wave at about 50 - 90MHz. In Europe, however, the Ham transmitting station will be installed soon around 50MHz. European observers, therefore, please contact me. I give you the latest information. Then American observers use FM broadcast stations around 80MHz. Some observers, however, use TV radio wave at around 50MHz. Since many radio observers use around 50MHz radio band, you had better select 50MHz radio transmitting staion. If you do not find the transmitting station, please contact me. I introduce a radio observer in your country (or area).