What is antenna gain ?

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Across
  1. 3. light
  2. 4. light : relative intensity
  3. 6. uniform in all direction
  4. 7. not wide
  5. 8. suppose
  6. 12. emit, give out
Down
  1. 1. towards the front
  2. 2. uses electricity
  3. 5. electrical waves, current
  4. 9. globe
  5. 10. reflecting device
  6. 11. light ray
  7. 13. circular