Questions :-
- What’s a PCB?Printed Circuit Board.
- Name some band definitions. L-Band - 1-2 GHz, S-Band - 2-4 GHz, C-Band - 4-8 GHz, X-Band - 8-12 GHz, Ku-Band - 12-18 GHz.
- What’s the definition of gain? The signal going into the device is smaller than the signal going out.
- What’s a definition of an amplifier? It’s a device that exhibits gain.
- Insertion loss? The signal going in is greater than the signal that’s coming out.
- Thermal impedance? A measure of how hot the device gets with varying electrical input.
- What’s the relation between dB and change of signal? +3 dB is 2 times bigger, +10 dB is 10 times bigger.
- What’s an octave? The bandwidth characterized by higher band being twice as much as lower band (100-200 MHz).
- What’s a decade? A bandwidth, where the higher band is 10x the lower band (100 MHz - 1 GHz).
- Skin effect? The signal is reported on the surface of the object, but not inside, e.g. a solid brick wall.
- VSWR? Voltage Standing Wave Ratio. The numeric representation of the device leak, written like X:1 where X is greater when the leak is greater and 1:1 is the absolute no-leakage VSWR.
- Describe an impedance matching circuit. A circuit capable of changing the impedance with different values for incoming and outgoing impedance.
- Describe circular polarization. The signal travels both vertically and horizontally.
- What’s the job of the amplifier? To increase the incoming signal.
- What is noise figure? The level of noise that a low-noise amplifier (LNA) is capable of discriminating.
- What’s a transfer curve? It is a graph of the output power versus the input power of an amplifier.
- What’s the 911 point? The point where the input power results in flames on the other end.
- What’s saturation point? The point where the amplifier loses its linearity of the transfer curve.
- What does balanced amplifier consist of? Two amplifiers stuck together.
- What is the filters function? To filter out all the unwanted radio signals.
- What filter types are there? Low-pass (all frequencies below are allowed to pass in), high-pass, bandpass (all frequencies of a given bandwidth are allowed) and band-reject.
- What are saw filters used for? Very low frequency filtering.
- What are mixers used for? To change the frequency of the signal.
- What’s a superheterodyne receiver? It’s a receiver that uses two mixers in a row.
- Describe VCO. Voltage-controlled oscillators change the frequency of the produced sine wave depending on the voltage they receive.
- Who is responsible for PLLs? Phase-locked loops are done by synthesizer, that samples the sine wave and if it’s not good enough, changes it.
