Profile: Quinstar Technology, Inc. specializes in millimeter-wave products, microelectronic assembly, rapid prototyping and mass customization. We also provide RF signal generating, amplifying and conditioning components to fully integrated & customized assemblies and subsystems for digital & analog sensor, communications & test applications. Our QMF series mode filters provide a solution to the critical need for mode purity when using TE01 mode circular waveguide. Due to the similarities between the TE01 and TM11 modes, even the slightest irregularities in the circular waveguide cause mode conversion from TE01 to TM11. The large waveguide diameters will readily propagate TEM1 modes, which degrade the purity of the TE01 signal. Each QMF series mode filter consists of a section of lossy wall waveguide. Because the higher order modes (TMM1,TEMN) have wall currents, they are sharply attenuated and do not propagate. Although the energy transferred to these modes is minimal, mode filters must be placed periodically along the transmission line. The TE01 mode, which does not have wall currents, passes through this section unaffected. The QMF series mode filters are available in circular waveguide sizes from 12.4 to 140 GHz. The QEP series balanced phase detectors enable phase comparison of two RF signals. They utilize GaAs beam lead diodes which offer significant advantages over other detector types. The diodes are carefully matched to achieve high isolation between RF ports, low DC offset, noise cancellation, and suppression of the adverse effect of amplitude modulation. The detected output is proportional to phase differences up to 180 degrees for two equal amplitude signals at the same frequency. Balanced phase detectors are typically used in phase bridges and phase modulated receiver systems. We are an ISO 9001:2000 certified company.