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Log Periodic Dipole Array

Log Periodic Dipole Arrays, or LPDA is a directional antenna with relatively constant characteristics across it's wide frequency range. Before you start constructing your own LPDA using the LPDA calculator below, please read chapter 10 of the 20th Edition of the ARRL Antenna Book (Other editions of the ARRL Antenna Book work as well, but may have the LPDA described in another chapter.) The LPDA calculator below calculates an 13 element LPDA based on the design parameter τ, the lowest frequency you shall use, and the design parameter σ. You need to decide which values you want to use, and the LPDA calculator will do the rest of the math for you. You don't need to build an LPDA with all the 13 elements, it you for some reason wants to have a shorter boom length, or doesn't need a bandwidth that large, you just stop by the element that suits your preferences.

Design parameter τ:		Select a value between 0,80 and 0,98, usually between 0,88 and 0,95.
Lower design frequency (MHz):		Insert value
Design parameter optimal σ:		Calculated
Design parameter σ:		A value between 0,03 and 0,06 is usually used.
Angle α:		Calculated
Length of shorting stub (m):		Calculated
Length of Element Ln (m):		Calculated
Length of Element Ln+1 (m):		Calculated
Length of Element Ln+2 (m):		Calculated
Length of Element Ln+3 (m):		Calculated
Length of Element Ln+4 (m):		Calculated
Length of Element Ln+5 (m):		Calculated
Length of Element Ln+6 (m):		Calculated
Length of Element Ln+7 (m):		Calculated
Length of Element Ln+8 (m):		Calculated
Length of Element Ln+9 (m):		Calculated
Length of Element Ln+10 (m):		Calculated
Length of Element Ln+11 (m):		Calculated
Length of Element Ln+12 (m):		Calculated
Distance Dn (m):		Calculated
Distance Dn+1 (m):		Calculated
Distance Dn+2 (m):		Calculated
Distance Dn+3 (m):		Calculated
Distance Dn+4 (m):		Calculated
Distance Dn+5 (m):		Calculated
Distance Dn+6 (m):		Calculated
Distance Dn+7 (m):		Calculated
Distance Dn+8 (m):		Calculated
Distance Dn+9 (m):		Calculated
Distance Dn+10 (m):		Calculated
Distance Dn+11 (m):		Calculated
Total length of array (m):		Calculated
Upper frequency limit (MHz):		Calculated
Upper frequency limit with Ln+11 as last element:		Total length with Ln+11 as last element:
Upper frequency limit with Ln+10 as last element:		Total length with Ln+10 as last element:
Upper frequency limit with Ln+9 as last element:		Total length with Ln+9 as last element:
Upper frequency limit with Ln+8 as last element:		Total length with Ln+8 as last element:
Upper frequency limit with Ln+7 as last element:		Total length with Ln+7 as last element:
Upper frequency limit with Ln+6 as last element:		Total length with Ln+6 as last element:
Upper frequency limit with Ln+5 as last element:		Total length with Ln+5 as last element:

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This page was last updated 15.05.08 .