UWB_RECEIVE_ANTENNA

This component consists of an SBlock component that reads a file of S-parameters representing the RF frontend and antenna of the receiver. The receive antenna also contains a loss component to allow scale of the overall loss of the antenna.

S-parameters can be measured using a network analyzer. In the default setup, they are created by conducting RF simulations of a series of filters. HighPassFilter_RFsim.dsn is used to generate the default S-parameter file.
After reading the S-parameters from the file, the SBlock component produces the equivalent impulse response for use in ADS Ptolemy simulations. For a practical impulse response to be produced, a high-frequency cutoff lowpass filter must be applied when S-parameters for a highpass filter are generated.

Note The SBlock N value must be large enough for the filter impulse response to adequately decay. The impulse response will be truncated after a time of N×TStep. Using the lowest acceptable value of N will speed simulation.

A receive antenna can capture only a portion of this energy; the portion of the total radiated power that a receive antenna can capture is determined by the receive antenna aperture, the distance between transmit and receive antennas, and the antenna gains. The receive antenna is modeled using an additional SBlock component and an attenuator. The receive antenna contains a 1/frequency roll-off term to account for the reduction of antenna aperture with frequency. An additional attenuator is applied to adjust the total loss of the antenna at each frequency to the expected value at 3 meters. For example, the antenna aperture at 5.5 GHz is given by the equation

l is the signal wavelength and the expected aperture loss of the antenna at three meters is given by the equation

If the directional gain of the antenna relative to an isotropic antenna is 0, then at 5.5 GHz the signal level the receive antenna delivers to the receiver is 57 dB below the total transmit power at 3 meters. The loss of the default receiver SBlock component is 45 dB at 5.5 GHz, so 12 dB of loss is applied by the attenuator. To adjust the signal level for distances other than 3 meters, the propagation loss model is applied with do equal to 3 meters.

The signal from the receive antenna goes to an amplifier; the noise figure of this amplifier can be set by the user. A lowpass filter following the amplifier limits the noise bandwidth of the receiver frontend.

For more details regarding generating S-parameter files, refer to UWB_TRANSMIT_ANTENNA.

Subnetwork

Name	Description	Default	Unit	Type	Range
TStep	Time step of the simulation	10 psec	Time	Real	>0

Pin	Name	Description	Signal Type
1	Input	Input to receive antenna	Timed

Pin	Name	Description	Signal Type
2	Output	Receive antenna input waveform modified by front-end and antenna characteristics. Signal level is adjusted to account for amount of energy capture in antenna aperture at distance do.	Timed