Insertion Loss

The insertion loss of our chokes is very small, quite a bit less than 0.1 dB.  Such a small amount of loss does not make any discernable difference in signal strength, either on receive or transmit.

However, even this small loss causes some power to be dissipated by the choke, which in turn causes heating of the ferrite core and the coax used to wind the choke.  This heating turns out to be the primary limitation that determines how much power the choke can handle.  This is why insertion loss is important.

Insertion loss is a function of frequency, rising with higher frequencies.  Worst case for these HF chokes will always be on the highest frequency used.  

For our broadband choke, Black Beauty "Broad" 160-10, this worst case insertion loss is about 0.06 dB at 30 MHz, which is 1.38%.  Best case loss for the same choke is on 160 meters where the loss is only 0.01 dB, which is 0.23%.  The Insertion Loss plot below tells the whole story.

Black Beauty HD Low 160-40 is optimized for 160 and 80 meters, and has very little loss on those bands.  The Insertion Loss plot for this choke, shown below, demonstrates this.  Worst case loss on 80 meters is about 0.005 dB, or about 0.12%.  This insertion loss is small enough so that it does not limit the power handling ability of the choke on 160 or 80 meters.  The power limitation in that case is the power limit of the coax used to wind the choke.  The HD (Heavy Duty) in the name of this choke alludes to this high power handling capability as well as to the use of two ferrite cores.  As a "bonus" this choke is also effective on 40 meters, where the insertion loss is about .02 dB, or 0.46%.  

Power limitations are illustrated on the Power page, click here to go to the Power page.  

Below are two charts that show the measured Insertion Loss of several Watts Engineering Labs Common Mode Chokes.

This measurements were made with an SWR very close to 1:1

Increased SWR causes increased Insertion Loss.  As a result, these Insertion Losses should be adjusted based on the SWR seen by the choke.  For any specific value of SWR, multiply the loss shown in the chart by the factor in this table.  That will yield the actual Insertion Loss in a system with that SWR.

The insertion loss of our chokes is very small, quite a bit less than 0.1 dB.  Such a small amount of loss does not make any discernable difference in signal strength, either on receive or transmit.

However, even this small loss causes some power to be dissipated by the choke, which in turn causes heating of the ferrite core and the coax used to wind the choke.  This heating turns out to be the primary limitation that determines how much power the choke can handle.  This is why insertion loss is important.

Insertion loss is a function of frequency, rising with higher frequencies.  Worst case for these HF chokes will always be on the highest frequency used.  

For our broadband choke, Black Beauty "Broad" 160-10, this worst case insertion loss is about 0.06 dB at 30 MHz, which is 1.38%.  Best case loss for the same choke is on 160 meters where the loss is only 0.01 dB, which is 0.23%.  The Insertion Loss plot below tells the whole story.

Black Beauty HD Low 160-40 is optimized for 160 and 80 meters, and has very little loss on those bands.  The Insertion Loss plot for this choke, shown below, demonstrates this.  Worst case loss on 80 meters is about 0.005 dB, or about 0.12%.  This insertion loss is small enough so that it does not limit the power handling ability of the choke on 160 or 80 meters.  The power limitation in that case is the power limit of the coax used to wind the choke.  The HD (Heavy Duty) in the name of this choke alludes to this high power handling capability as well as to the use of two ferrite cores.  As a "bonus" this choke is also effective on 40 meters, where the insertion loss is about .02 dB, or 0.46%.  

Power limitations are illustrated on the Power page, click here to go to the Power page.