# 47 CFR 73.160 - Vertical plane radiation characteristics, f(θ).

(a) The vertical plane radiation characteristics show the relative field being radiated at a given vertical angle, with respect to the horizontal plane. The vertical angle, represented as θ, is 0 degrees in the horizontal plane, and 90 degrees when perpendicular to the horizontal plane. The vertical plane radiation characteristic is referred to as f(θ). The generic formula for f(θ) is:

(b) Listed below are formulas for f(θ) for several common towers.

(1) For a typical tower, which is not top-loaded or sectionalized, the following formula shall be used:

(2) For a top-loaded tower, the following formula shall be used:

See Figure 1 of this section.

(3) For a sectionalized tower, the following formula shall be used:

See Figure 2 of this section.

(c) One of the above f(θ) formulas must be used in computing radiation in the vertical plane, unless the applicant submits a special formula for a particular type of antenna. If a special formula is submitted, it must be accompanied by a complete derivation and sample calculations. Submission of values for f(θ) only in a tabular or graphical format (i.e., without a formula) is not acceptable.

(d) Following are sample calculations. (The number of significant figures shown here should not be interpreted as a limitation on the number of significant figures used in actual calculations.)

(1) For a typical tower, as described in paragraph (b)(1) of this section, assume that G = 120 electrical degrees:

θ | f(θ) |
---|---|

0 | 1.0000 |

30 | 0.7698 |

60 | 0.3458 |

(2) For a top-loaded tower, as described in paragraph (b)(2) of this section, assume A = 120 electrical degrees, B = 20 electrical degrees, and G = 140 electrical degrees, (120 + 20):

θ | f(θ) |
---|---|

0 | 1.0000 |

30 | 0.7364 |

60 | 0.2960 |

(3) For a sectionalized tower, as described in paragraph (b)(3) of this section, assume A = 120 electrical degrees, B = 20 electrical degrees, C = 220 electrical degrees, D = 15 electrical degrees, G = 140 electrical degrees (120 + 20), H = 235 electrical degrees (220 + 15), and Δ = 115 electrical degrees (235−120):

θ | f(θ) |
---|---|

0 | 1.0000 |

30 | 0.5930 |

60 | 0.1423 |