Passive relay

Passive relay

Passive relay is special type of link, which enables to create a link „behind a corner“. It is suitable when there is no direct visibility and in the case that the distances are quite short. We place 2 antennas connected by short cable on place with direct visibility to both operating positions and set them on both. The main advantage of this link is that it does not need active device and power in the place of common visibility.

It is easy to define main link parameters with the help of our calculation.

How to proceed

Choose frequency range (by clicking on relevant box). Rewrite values in separate cells according to your parameter link, use only positive numbers, in decimal position put a dot!! If you do not use any of the elements (e.g. pigtail, lightning arrester...) enter 0 into the relevant cell. The results are shown immediately after each value change. You cannot enter into cells, which show results.

Calculated value

Radiated power

By this calculation you can check whether the maximum-radiated power allowed in your country is not exceeded. Allowed radiated power is different for 2,4 GHz and 5 GHz range. 5 GHz range is usually divided into several parts with different radiated power. You will find additional information in instructions for active Wi-Fi equipment and at telecommunication authority.

Receiving value

The value of received signal at the entry of the device is shown in this cell. For best function of this link it is necessary that the level is higher than sensitivity of the receiver (sensitivity is specified with particular Wifi appliance according to bit rate). Attention: sensitivity is given in negative numbers! It is also necessary to count with margin during unfavourable conditions (snow, rain, interference.)

Fresnel zone

Fresnel zone is an area where most of the power between antennas is transmitted, it is cigar shaped. If there is a barrier in this area, the transmission attenuation increases. Calculated radius is in the middle of the link and at the end it decreases.