10-60 db attenuator T pad in and out resistors to ground 51 ohm resistor between in and out: 10 db = 51 ohm (71 ohm ideal ground) 20 db = 220 ohm (61 ohm ideal ground) 30 db = 820 ohm 40 db = 2.7 kohm 50 db = 8.2 kohm 60 db = 27 kohm values are not ideal, but are common resistors grounding resistors SHOULD be higher values (60-70 ohm) for 10 and 20 db but you can use a dp6t rotary switch and just leave those two grounded off the common, OR if you have a lot of 50ish resistors you can make those dedicated also with adjusted values a dpdt toggle switch is also needed to allow for the attenuator to be out of line completely (0db attenuation). Get one with center-off to allow for antenna-out-of-line (air gap connection in switches) only also for maximum attenuation. or use a relay for a better air gap. make a -20db T atten with two 39 ohm and one 10 ohms make a -40db T atten with two 47 ohm and one 1 ohm