The transmitter is identical to the NEXRAD  WSR-88D transmitter and is supported by the NWS National Reconditioning Center in Kansas City, MO. The S-band transmitter  operates at dual RF pulsewidths of 1.5 and 5.0 μs and variable PRF (pulse repetition frequency) ranging between 300 and 1300 p.p.s. The transmitter has demonstrated a phase stability of better than 57 dB. The performance is achieved with a klystron amplifier cathode pulsed by an all-solid-state line-type modulator. Special attention is given to modulator pulse regulation, output regulation and inverter timing in the filament supply, and spectral conditioning in the solid-state RF driver. The peak modulator power level of 1.5 MW is capable of producing a peak RF output in excess of 750 kW. The transmit pulse is tapered and filtered for minimum RF interference. The 28 foot reflector is a high-compliance aluminum structure providing -28 dB first sidelobes and at least -31 dB integrated cross polar isolation.

Polarization switching is done by an NCAR built mechanical switch which will provide 49 dB transmit isolation. For alternating H/V pulses, this isolation is comparable to a dual transmitter configuration. A separate receiver for each channel provides 40 dB receive isolation. Copolar and  crosspolar receivers are used to provide high data quality differential reflectivity and differential phase measurements.

Pulse pair and dual polarization processing is performed by a Vaisala RVP8 receiver. The processor is PC based and ingests the I/Q time series from the RVP8. Real time ground clutter mitigation is accomplished with the NCAR developed CMD (Clutter Mitigation Decision)  algorithm. The spectral based clutter filter provides about 50dB clutter rejection.


S-PolKa Radar Characteristics


S Band

Ka Band


7, 20 ft. containers


Site requirements

leveling and access



Diesel generator



2.7 -- 2.9 GHz

34.7 GHz

Pulse width

1.0 to 1.5 µsec-tapered

0.3 to 0.5 µsec


30 -- 1300 Hz

800 – 1000 Hz

Peak power

>600 kW

50 kW

Receivers (2)

H & V simultaneously

H & V simultaneously

Noise power

-114 dBm

-104 dBm

Radar Noise figure

3 dB

5.3 dB

Dynamic range

90 dB

76 dB


1 MHz, typical

2 MHz, typical

Minimum detectable dBZ at 50km/1km

-10.4 dBZ/-44.4 dBZ

-6.3 dBZ/-40.4 dBZ

Polarization switching

H-V alternating, H-V simultaneous or H or V only

Transmit H, receive H and V or H-V simultaneous

Mechanical switch isolation

47 dB measured



Parabolic, center feed

Parabolic, center feed


44.5 dB including waveguide loss

45.9 dB


8.5 m (28 ft.)

0.7m (28”)


0.92 degrees

0.93 degrees

First sidelobe

better than -28 dB

-26 dB

Isolation (ICPR)

better than -31 dB

better than -22 dB

Scan rate

Up to 12°/s for PPIs; 6 deg/s for RHIs


Wind limit

30 m/s, operation / 54 m/s, survivability


Data system



Number of range gates

Maximum: 3092; Typically: 992

Typically: 1000

Gate spacing

37.5 -- 150m

45 – 75m

Number of samples



Clutter filter

50 dB suppression

50 dB suppression

Times series (I/Q) capability



Real time scientific display

CIDD, Jazz

CIDD, Jazz

Recorded variables

PHH, PVV, V, W, fDP, rHV, NCP, ZH, ZDR, LDR, Kdp, raw covariances


Recording medium

RAID, CfRadial format

RAID, CfRadial format