I'm working on a 915MHz mixer design, and just run into a challenge of unavailability of these components

1.Varactor diode BB131 (philips)
2.Feedback amplifier transistor AT-41486 (agilent)
3.Schottky diode BAT15-04W
4.RF transformer JTX-2-10T

pls I need suggestions for possible substitutes for the components. thanks in advance