1, Frequency range: The Distributor used in the entire cable television network, it should have broadband frequency characteristics;
Input output Impedance: Cable TV network RF interface impedance should be 75 euro, in order to achieve impedance matching, so the distributor input and output end impedance should be 75 euro;
2, Allocation of loss: in the system always want to access the distributor loss of the smaller the better. The allocation loss LS is related to the number of allocations of N, in an ideal case ls=10lgn, when the n=2 two distributor allocation loss of 3dB. In fact, in addition to the loss of equal signal, there is also a part of the distribution device itself has attenuation, so the total is larger than the calculated value. In the case of 550-750mhz, the loss of 3.5db,4 distributor often takes a value of 8dB for the allocation loss of the two distributor.
3, Mutual isolation: Mutual isolation is also known as distribution segregation. If a signal is added to one of the output terminals of the distributor, the difference between the signal level and that of the other outputs is isolated, and the output of the distributor is generally required to be more than 20dB in isolation. If the standing wave ratio is too large, the transmission signal will produce reflection on the input or output of the distributor, which has bad effect on the image quality, such as ghosting. The distributor is also divided into an overcurrent distributor, an outdoor distributor and an indoor distributor.
4, Standing wave ratio: all known as voltage standing wave ratio, also known as VSWR and SWR, for English voltage Standing wave ratio shorthand.
The standing wave ratio is a numerical value to indicate whether the antenna and the radio transmitter match. If the value of the SWR is equal to 1, it means that the radio waves transmitted to the antenna do not have any reflection, all launched, this is the ideal situation. If the SWR value is greater than 1, it means that some of the waves are reflected back and eventually become heat, causing the feeder to warm up. The reflected waves at the transmitter outlet can also produce quite high voltage, which may damage the launch pad.
5,Reflective loss refers to the load directly connected to the signal source on the power and due to the distributor mismatch caused by the ratio of reflection power to the DB representation
6, RF characteristics