Log Periodic Antenna Feed Arrangements

- notes and details on the feed or feeder arrangements and system used feeding a log periodic dipole array.

Log periodic antenna tutorial includes:

    •  Log periodic array basics
    •  Log periodic theory
    •  Feeder arrangements

Feed arrangements

The log periodic dipole antenna presents a number of difficulties if it is to be fed properly. The feed impedance is dependent upon a number of factors. However it is possible to control this by altering the spacing, and hence the impedance for the feeder that connects each of the dipole elements together. Despite this the impedance varies with frequency, but this can be overcome to a large extent by making the longer elements out of a larger diameter rod. Even so the final feed impedance does not normally match to 50 ohms on its own. It is normal for a further form of impedance matching to be required. This may be in the form of a stub or even a transformer. The actual method employed will depend to a large degree on the application of the antenna and its frequency range.

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