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Field Strength

RF Signal Level Calculator... VE3KL

Input Area

See instructions below ... 50 Ohm System...Half wave dipole
Enter positive numbers greater than zero


Field Strength
[Microvolts per meter]

Reference Bandwidth
(Spectrum Analyzer Bandwidth)

Receiver Bandwidth

Electric Field [dBuV/m]
(with respect to Reference Bandwidth)
Received Power [dBm]
Received Voltage [Microvolts]
Received S Units

What This Calculator Does

This calculator computes the received noise levels in a communication receiver given the input frequency and electric field strength. The following assumptions are made:

The receive antenna is a standard dipole tuned to the frequency of operation.

The input noise level (usually measured with a spectrum analyzer with a noise bandwidth called the Reference Bandwidth) is given in microvolts (RMS) where the spectrum is assumed to be flat over the bandwidth of the measurement.

The Receiver noise Bandwidth is known. Typical values are 2.4 KHz for SSB operation, and 50 Hz for PSK31 operation.

How to Use The Calculator

Input the frequency in MHz.

Input the electric field strength at the receive antenna position in MicroVolts per meter.

Input the Reference Bandwidth in KHz (usually 10 KHz).

Input the Receiver Bandwidth in KHz ( 2.4 KHz for SSB, 50 Hz for PSK31).

The calculator then computes the received power and voltage at the input to the receiver as well as the power measured in S Units

The relationship between PdBm and S Units is given as:

Sunits = (Pdbm +73)/6.00 + 9.0

Amateur Radio Requirements...RF

For SSB operation the base noise level (noise floor for a typical receiver) for the 1.8-18 MHz band is -129 dBm while the base noise for the 10-30 MHz range is -132 dBm. These noise levels only produce a 10 dB SNR at the receiver output. The minimum signal level for effective communication is approximately 6 dB above the base noise level The noise figure of typical receivers is 11 dB for the low frequencies and 8 dB for the high frequencies.