Telephone

As a frequency gets higher, the wave length gets shorter, and the directness and refractiveness increase, It approaches the properties of light.

Also, if there is an obstacle that is hard for the radio wave to pass through, on the other side of this obstacle, the radio wave becomes weak, it refracts and multi-path noise (feedback) occurs.

* Basically, when a wave length is long, the cordless phone's antenna should be long. However, when a wave length is short, the antenna should be also be short, This is why the length of antenna of the 900 MHz cordless phone is shorter than 43/49Mhz cordless phone.

When a radio wave is weak, (when the electric signal is small), noise increases. For example, the further the distance between the base unit and the portable unit (inverse proportion to distance squared), the radio wave will become weaker And, at a certain level, the noise (radio wave disturbance). There is also the possibility that the cordless phone may receive interference when operated near a radio or TV station, electric cable, etc.

Points to pay attention to
Even within a normal transmission range of 100m, if there is a building, a wall or something that might cause interference, the transmission conditions become worse. In cases that are extremely bad, the transmission range narrows extremely down to only 5 - 30m.

With the spread of electrical products and the increase of wireless communication products, noise and interference also occur in large quantities.

In some cases where noise is interfering with the cordless phone's radio waves, as the cause, which is this noise, cannot be seen by the eye, many people think that the phone is no good or is defective. Careful attention concerning this is necessary.

In usage, please note the following

A cordless phone's radio wave (electric field strength) is transmitted in a fixed direction. Therefore, in a weak electric field, (when the radio waves are weak) using the portable unit in an inclining position (not up and down) will increase possibility of noise occurrence.

Environmental conditions of radio wave
(Effect on Radio Waves)

virtually no influence small influence
marginal influence strong effect

In the case of ferroconcrete walls, there is no difficulty with conversation in the same room. However, a conversation that is in a room divided by a ferroconcrete wall may be difficult. This is because the radio waves will not transmit well.