Question E2A04:
What is meant by the “mode” of an amateur radio satellite?  

Choices:  
A: Whether the satellite is in a low earth or geostationary orbit  
B: The satellite’s uplink and downlink frequency bands  
C: The satellite’s orientation with respect to the Earth  
D: Whether the satellite is in a polar or equatorial orbit    

Correct Answer is  B: The satellite’s uplink and downlink frequency bands  

Correct answer: B — The satellite’s uplink and downlink frequency bands.

Why B is correct:
- In amateur satellites, “mode” names the pair of frequency bands used: one for the uplink (you transmit to the satellite) and one for the downlink (the satellite transmits to you).  
- Example: Mode U/V means uplink on the 70 cm band and downlink on the 2 m band.

Why the other choices are incorrect:
- A: Orbit type (LEO vs GEO) describes altitude and orbital period, not the frequency bands used.
- C: Orientation is the satellite’s attitude, unrelated to its operating bands.
- D: Polar vs equatorial refers to orbital inclination, not the radio bands.

Useful rules of thumb:
- Two-letter “modern” notation: first letter = uplink band, second letter = downlink band.
  - V: 2 m band, about $144$–$148$ MHz
  - U: 70 cm band, about $420$–$450$ MHz
  - L: 23 cm band, about $1260$–$1270$ MHz (uplinks commonly around $1268$ MHz)
  - S: 13 cm band, about $2400$–$2450$ MHz
  - X: 10 GHz band (X-band), about $10.4$ GHz
- Legacy “Mode” letters you may still see:
  - Mode B = U/V (uplink 70 cm, downlink 2 m)
  - Mode J = V/U (uplink 2 m, downlink 70 cm)
- Mode indicates frequency bands only; it does not specify modulation type (FM vs linear), bandwidth, or transponder style.