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diff --git a/4.-Antenna-Array-Setup.md b/4.-Antenna-Array-Setup.md index d66200c..dec259c 100644 --- a/4.-Antenna-Array-Setup.md +++ b/4.-Antenna-Array-Setup.md @@ -4,8 +4,39 @@ For standard direction finding you will need five identical omni-directional ant Note, when mounting antennas, the convention is to mount them in a clockwise direction when seen from a top-down perspective. So, antenna zero is the first antenna pointing towards zero degrees, antenna one is to the coordinate to the right of antenna one, and so on. -The explanations below provide more detail to the math behind the antenna spacing. However, in practice, you only need to decide what type of array you want to use, and then use an [Excel sheet calculator](https://docs.google.com/spreadsheets/d/1w_LoJka7n38-F0a3vgaTVcSXxjXvH2Td/edit?usp=sharing&ouid=113401145893186461043&rtpof=true&sd=true) to calculate the spacing and placement coordinates required. +The explanations below provide greater detail on optimizing your antenna array. However, the easiest way to get started is to simply use our Excel antenna array spacing calculator `Antenna_Array_Size_Calculator.xlsx` available on this repo at https://github.com/krakenrf/krakensdr_docs/tree/main/antenna_array +# Using the Excel Calculator +In the Excel calculator yellow boxes indicate numbers you can change. + +## Spacing Multiplier Explained +Both the spacing multiplier and frequency determine array sizing. The spacing multiplier is a value that is multiplied against the wavelength of interest resulting in the 'interelement spacing' of the array. The interelement spacing is the distance between each element in the array. + +In all situations the spacing multiplier must be kept under 0.5 to avoid ambiguities (more than one possible bearing solution). Ideally, you also want to keep the spacing multiplier above around 0.2. The larger the spacing multiplier the greater the resolving resolution of the array. This means better multipath handling. Below 0.2 the resolution becomes too poor. + +## Frequency to Array Radius +Enter your frequency here, and it will show you the antenna radius for that particular frequency, for a range of spacing multipliers. + +## Acceptable Frequency Range for a Fixed Array Radius +Once you have chosen a practical array radius for your application, enter the radius in this section. The green boxes will show you the range of frequencies that will work with this array radius. + +## Array Coordinates for Radius +This section will show you the exact coordinates to place your antenna elements, for a given array size. Note that these coordinates need to be rotated so that ANT-0 points towards the direction of movement. + +# Antenna Spacing Template +You may wish to use our antenna spacing template which will help with accurate antenna placement. The more accurate your array, the better your results will be. + +Files for 3D printing and paper printing can be found in this repo at https://github.com/krakenrf/krakensdr_docs/tree/main/antenna_array + +For both templates print the center pentagon and five arms separately, then glue them together. + +**Each hole is spaced at 50mm radius intervals.** So you have radius spacings of 100mm, 150mm, 200mm, and 250mm. These spacings cover the following frequency range: + +100mm : 510 - 1275 MHz +150mm : 340 - 850 MHz +200mm : 255 - 637 MHz +250mm : 204 - 510 MHz + # Antenna Arrangements ## Uniform Circular Array (UCA) |