What is space wave propagation? State the factors which limit its range of propagation. Derive an expression for the maximum line of sight distance between two antennas for space wave propagation.
CBSE OUTSIDE DELHI - SET 1 NORTH 2016
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Space Wave Propagation: The mode of propagation in which radio waves travel, along a straight line, from the transmitting to the receiving antenna. Limiting Factors:
From the figure, we have $(\text{R} + \text{h})^{2} = \text{R}^{2} + \text{d}^{2}$ Or $2\text{Rh}\cong\text{d}^{2}(\text{as}\text{h}^{2} < < 2\text{Rh})$ $\therefore , \text{d} = \sqrt{2\text{Rh}}$ For a transmitting antenna of height$\text{h}_{T}$, and a receiving antenna of height$\text{h}_{R}$, the maximum line of sight distance becomes, $\text{d}_{M} = \sqrt{2\text{Rh}_{T}} + \sqrt{2\text{Rh}_{R}}$.
- Curvature of the earth.
- Insufficient height of the receiving antenna.
From the figure, we have $(\text{R} + \text{h})^{2} = \text{R}^{2} + \text{d}^{2}$ Or $2\text{Rh}\cong\text{d}^{2}(\text{as}\text{h}^{2} < < 2\text{Rh})$ $\therefore , \text{d} = \sqrt{2\text{Rh}}$ For a transmitting antenna of height$\text{h}_{T}$, and a receiving antenna of height$\text{h}_{R}$, the maximum line of sight distance becomes, $\text{d}_{M} = \sqrt{2\text{Rh}_{T}} + \sqrt{2\text{Rh}_{R}}$.
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