The Bird RF company is based in the US and is widely known for supplying RF measurement instruments including the iconic Bird 43 power meter

Founded in 1942 by J Raymond (Ray) Bird, the company has been making RF test and measurement products which have gained a unique place in the industry.

Bird 43 thuline - inline wattmeter / power meter that gives forward and reverse power readings that can be converted to VSWR.
Bird 43 Thuline ® Wattmeter that provides forward and reverse power

The Bird company manufactures and supplies a host of RF products ranging from RF power measurement instruments, through to coverage testing tools as well as radio infrastructure equipment off air testing systems.

Although the Bird company is probably most famous for its iconic Bird 43 through line directional power meter, it has a very much wider offering these days.