Overview

From APPLIED MICROWAVE & WIRELESS, VOL. 12, NO. 6, JUNE 2000

When stand-alone passive components are not readily available as standard off the shelf commercial units, lab-built engineering models are often the best solution. At other times, passive circuits may be critically needed as test accessories when unanticipated problems arise during final subsystem and system testing. In these situations, time constraints can be met with prototype units that can be designed, assembled, and tested in only a few hours, as long as printed circuit boards (PC boards) are not used.

This type of component construction is readily accomplished at low power levels with frequencies below 100 MHz. At VHF, passive circuits such as band-pass filters can be readily implemented using standard die cast aluminum boxes as housings. Coaxial connectors and some of the circuit elements are screw assembled to the housing. Other circuit elements are assembled using soldered connections inside the housing.

Many standard commercial components are regularly manufactured without PC boards, but are available for surface mounting to higher level PC boards. They include passive units, such as low-pass and high-pass filters, equalizers, attenuators, terminations, RF transformers, DC blocks, power dividers, and directional couplers. Quasi-active units such as mixers, detectors, and frequency multipliers are also produced without PC boards. Active capabilities are achieved via external excitation. Many tubular components operating...