1:4 resistive splitter/combiner PCBAs
(Download the Data Sheet)
![rfcomb4r-att-pcba.jpg](../../../images/rfcomb4r-att-pcba.jpg)
The rfcomb4r series features a couple of miniaturized 1:4 resistive RF splitter/combiners.
In applications where high insertion loss is desired, those type of splitter/combiners are significantly lower cost and smaller size than the usual RF splitter/combiners on the market, which are optimized for exceptionally low insertion loss.
A 1:4 resistive splitter/combiner is basically nothing else but five resistors connected together at one terminal. The theoretical insertion loss is 12dB, plus losses in connectors, substrate, etc.
Common features of all models:
small, 30x30mm 4-layer printed circuit board
four mounting holes in the corners, spaced 25mm, intended for mounting using M3 screws/spacers
common port is SMT SMA jack
four tributary ports are IPX/U.FL, ideal for direct connection to cellular modems via IPX/U.FL pigtails
rfcomb4r
This is the basic variant with just the resistive splitter/combiner and no additional on-board attenuators. As a result, it features identical insertion loss (14dB) between the tributaries and the SUM port as isolation between the tributaries
![VNA plot of rfcomb4r insertion loss](../../../images/rfcomb4r-1.png)
rfcomb4r-att30
This combiner features an additional on-board attenuation of 20dB in each tributary and 10dB in the SUM port. This results in an overall insertion loss of about 43dB. The isolation between tributaries is 10dB higher.
![VNA plot of rfcomb4r-att30 insertion loss](../../../images/rfcomb4r-att30-3.png)
![VNA plot of rfcomb4r-att30 isolation](../../../images/rfcomb4r-att30-iso.png)
rfcomb4r-att40
This combiner features an additional on-board attenuation of 30dB in each tributary and 10dB in the SUM port. This results in an overall insertion loss of about 53dB. The isolation between tributaries is 20dB higher.
![VNA plot of rfcomb4r-att40 insertion loss](../../../images/rfcomb4r-att40-4.png)
![VNA plot of rfcomb4r-att40 isolation](../../../images/rfcomb4r-att40-iso.png)
Mechanical Outline
![mechanical outline of rfcomb4r](../../../images/rfcomb4r-att-mechanical.png)