A microwave, power splitter/combiner (20) is formed as part of a multilayer laminate (27, 28, 29, 33, 34) such that two ports (22, 23) are connected by plated vias (31, 32) to conductive pads (29, 30) connected across an isolation resistor (27). Furthermore, a microwave circuit is provided in the form of a multi-layer laminate including a substrate carrying a resistive layer which has been etched to define at least one resistor, a dielectric membrane covering the resistor, a conductive layer defining at least part of an electrical circuit, and said at least one resistor is electrically connected to the conductive layer by vias extending through the dielectric membrane.