RF, PW, PRI, and PRF questions Flashcards
What factors of radar performance, or radar design, does frequency (RF) affect?
Antenna Size, Range and Beamwidth.
Frequency (RF) is inversely proportional to wavelength (λ) f = c / λ.
How does this affect antenna size?
Antennas are designed to match the signal wavelength, therefore the longer the wavelength (lower RF), the larger the antenna and vice versa.
How is RF energy affected passing through the atmosphere?
RF energy passing through the atmosphere will be attenuated via
absorption and scattering.
- Absorption effects EM energy at RFs above 100Mhz.
- Scattering effects EM energy at RFs above 3000Mhz.
What aspects of a radars performance / capabilities are affected by PRI.
Maximum Theoretical Range, Average Power, Blind Speeds, Pulses
Per Paint.
What factors of a radars performance / capabilities are affected by PW?
Range resolution, Minimum Range and Average power.
How could a radar be designed with a large PW (long range due
high average power) without the subsequent loss of range resolution?
Pulse compression. Pulse is coded for transmission so that it can
be compressed by the receiver.
What factors of a radars performance / capabilities are affected by Scan Rate?
Pulses per Paint.
What does PRI effect
Maximum theoretical range = from greater PRI
Therefore lower PRF (data rate)
What does PW effect
Greater PW = Greater average power
therefore Reduced Range Resolution and Increased minimum range (Bad)
What does Frequency effect
Higher Frequency = Smaller antenna, therefore narrower beam (greater directivity, increased range)
