Consider the following statements about RF/microwave attenuators: 1) A dissipative attenuator has a fixed value of attenuation. 2) A reflective attenuator has a fixed value of attenuation. 3) Both dissipative and reflective attenuators are available only with fixed attenuation. 4) Both dissipative and reflective attenuators are available with either fixed or variable (tunable/step) attenuation. Which of the above are correct?

Introduction:
Attenuators reduce signal power by a known amount. They can be dissipative (absorptive) or reflective (using controlled reflection). The question tests knowledge of whether these attenuators are limited to fixed attenuation or may be variable.

Given Data / Assumptions:

• Dissipative attenuators use resistive networks or PIN-diode/RFIC absorptive elements.
• Reflective attenuators vary mismatch to control returned vs delivered power.
• Commercial parts exist in fixed pads and variable/step forms.

Concept / Approach:
Dissipative attenuators are available as fixed pads (e.g., 3 dB, 6 dB) and as variable/step attenuators using PIN/FET elements. Reflective attenuators (e.g., shunt PIN diode bridges) can also provide continuously variable or step attenuation by changing bias, not just fixed values.

Step-by-Step Solution:

Verification / Alternative check:
Catalogs show fixed pads (X dB) and step/continuous attenuators in both absorptive and reflective designs.

Why Other Options Are Wrong:

• A/B/C: Each includes false claims that attenuation must be fixed.

Common Pitfalls:
Confusing reflective attenuators with isolators; assuming only pad-style attenuators exist.

Final Answer:
4 only