Thruline^® Series

RF Wattmeters, Plug-In Elements and Line Sections

Bird offers a wide selection of portable insertion-type instruments for measuring forward and reflected power in coaxial transmission lines. Thruline® instruments can be left in the line for continupus monitoring of the transmitter power output or the amount of RF power reflected by an antenna.

Bird RF wattmeters and other thru-line instruments are based on a "lumped constant" directional coupler. The directional coupler is called an element. Many users also call it a "slug" ro "plug-in". Each plug-in element (or coupler) samples the voltage at the point of insertion and samples the current via a loop. Turning the element 180° reverses the loop (and consequently the current pick-up) while the voltage sample remains inchanged. By proper combination of the two parameters, we obtain an RF voltage proportional to the square root of main line RF power. The RF sample is then rectified and a DC signal proportional to the RF envelope is delivered to the meter.

Compatible Bird Plug-In Elements

• 7/8" RF Elements for QC-TYpe or 7/8" Line Sections
• 1-5/8" RF Elements for 1-5/8" Line Sections
• 3-1/8" RF Elements for 3-1/8" Line Sections
• 4-1/16" RF Elements for 4-1/16" Line Sections
• 6-1/8" RF Elements for 6-1/8" Line Sections