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Wideband two-ray channel environment

**Library:**Phased Array System Toolbox / Environment and Target

The Wideband Two-Ray Channel block propagates wideband signals from one point in space to multiple points or from multiple points back to one point via both the direct path and the ground reflection path. The block propagates wideband signals by (1) decomposing them into subbands, (2) propagating subbands independently, and (3) recombining the propagated subbands. The block models propagation time, propagation loss, and Doppler shift. The block assumes that the propagation speed is much greater than the object's speed in which case the stop-and-hop model is valid.

When the origin and destination are stationary relative to each
other, the block output can be written as *y(t)
= x(t – τ)/L*. The quantity *τ* is
the delay and *L* is the propagation loss. The delay
is computed from *τ = R/c* where *R* is
the propagation distance and *c* is the propagation
speed. The free space path loss is given by

$${L}_{fsp}=\frac{{(4\pi R)}^{2}}{{\lambda}^{2}},$$

where λ is the signal wavelength.

This formula assumes that the target is in the far-field of
the transmitting element or array. In the near-field, the free-space
path loss formula is not valid and can result in losses smaller than
one, equivalent to a signal gain. For this reason, the loss is set
to unity for range values, *R ≤ λ/4π*.

When there is relative motion between the origin and destination,
the processing also introduces a frequency shift. This shift corresponds
to the Doppler shift between the origin and destination. The frequency
shift is *v/λ* for one-way propagation and *2v/λ* for
two-way propagation. The parameter *v* is the relative
speed of the destination with respect to the origin.

`phased.FreeSpace`

|`phased.LOSChannel`

|`phased.TwoRayChannel`

|`phased.WidebandFreeSpace`

|`phased.WidebandLOSChannel`

|`phased.WidebandTwoRayChannel`

`fogpl`

|`fspl`

|`gaspl`

|`rainpl`

|`rangeangle`

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