Which Antenna Duplexer is right for you?
There are several factors involved in choosing the right duplexer for your application. Most consider only TX power and frequency offset when deciding whether a duplexer fits their application. While these factors are essential, there are a number of other considerations that should be taken into account before settling on the dupllexer that best fits the needs of your application.
Cost: Getting something that works well for less is always good. Getting something for less that works poorly can lead to frustration. When Purchasing or Accounting are making product decisions on cost analysis, short terms gains often turn into long term losses.
Form Factor: Site rental costs often include the amount of vertical rack space utilized. Customers may have a small space for their radio equipment or may have filled their rack/cabinet with other equipment. As so, the space they have to work with is limited.
Transmit (TX) Power: RF equipment has power limitations. Most PA’s don’t exceed 150 watts and most equipment fits up to 150 watts with the main exception being mobile duplexers.
TX-RX Offset: This will determine the size and number of cans required to achieve the necessary TX-RX and RX-TX to prevent receiver desense. The more narrow the offset means larger cavity resonators and/or more cans.
TX-RX and RX-TX Isolation: Along with TX-RX offset this will determine the size and number of cavities required to prevent receiver desense.
Insertion Loss: This typically falls out based on the “type” choice of duplexer (bandpass, pass notch, hybrid bandpass and pass notch), the TX-RX offset, and the number of cans required to meet the necessary TX-RX and RX-TX isolation needed to prevent receiver desense.
Site Density (collocated transmitters and receivers): This factors into which “type” duplexer is the right choice (bandpass, pass notch, hybrid bandpass and pass notch).
Single frequency or pass bandwidth: A duplexer can be used for a repeater TX-RX pair, it can be used to route a combiner (multiple transmitters) and multicoupler (multiple receivers) to a single antenna, and it can be used to route two simplex radios to a common antenna.
Every “advantage” you obtain from your choice in duplexer will have it’s cost and sometimes costs.