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#Localizer antenna code

I believe this is what is used for Aspen I-KPN. We see the signal radiated by the front lobe, but with an inverted signal, is equivalent to the signal radiated by the back-lobe in a conventional localizer.

Why using the front lobe of the radiation pattern? Just because this is the most efficient, the gain in the front lobe being larger than in the back lobe.įrom a signal standpoint, comparing front beam, back beam and back beam with reversed signal to create a "back-course" guidance: I believe each of the log periodic antennas has the shortest element on its front (up on the picture), and therefore the front lobes are used to transmit the guidance signal. I-KPN array, facing 303°, from Google Street View This is visible on this picture of the array taken from its NW: In the case of I-PKN, the signal is not sent by the back of the antennas, but by the front, like a regular LOC/ILS approach. It's only use is during the missed approach. It's not a back-course in the sense it would give an additional access to the opposed runway for free, like other localizers do using the back lobes of their antennas.

I-KPN course is referred to as a "back-course". I-KPN directed at 301° is used in the missed approach trajectory to provide the guidance to return to the holding via LINDZ waypoint. Aspen has a LOC/DME approach based on two localizers: I-ASE classic, directed at 331°, is used to land and has no back-course. If so, are there any airports where this has been done?Īspen back-course localizer I-KPN which motivates your question is possibly one of these localizers with inverted signal. While the very usual case is the back-course is sent using the back lobe (making back-course and back lobe near synonymous), in the unusual I-PKN, the front lobe is used to create a back course guidance.

One related to the approach procedure, the back-course, which refers to the direction opposite to the approach the localizer is primarily used for.

One related to the antenna, the back lobe, which is the area where the antenna radiates rearward, as many antennas do.

In this section I'm going to separate two concepts: See this array diagram showing signal amplitude and phase for each course and clearance antenna. As the inputs are symmetrical relatively to the array center, except the SBO phase, practically we would just have to invert SBO phase. This boils down to swapping the antenna inputs. Localizer array at Melbourne airport (seen from the back), source Conceptually this is obtained by reversing the order of the individual antennas of the localizer array, the leftmost antenna becomes the rightmost antenna, etc. Indicates if the navaid equipment has been flight checked.Can we reverse the guidance from the transmitter?Ĭan a Localizer Backcourse signal be reversed (at the site antenna)?įrom a technical standpoint it's entirely possible, but both beams, front and back, are reversed at the same time. The year the magnetic variation was measured. The accuracy of the measured angle between Magnetic North and True North at the VOR and at the time reported in dateMagneticVariation The following rule of thumb applies: ""variation east-magnetic least, variation west-magnetic best"". Therefore, magnetic bearing + magnetic variation = true bearing.

By convention, the measure is expressed as a positive number if Magnetic North is to the east of True North and negative if Magnetic North is to the west of True North. The measured angle between Magnetic North and True North at the VOR and at the time reported in dateMagneticVariation. Indicates if the navaid equipment is mobile.

#Localizer antenna code

The long name given to the navaid equipment.Ī code indicating the type of emission, as defined at the 1979 ITU World Administrative Radio Conference. The identifying code given to the navaid. The angular difference between True North and the station declination (Magnetic North - as indicated by the station).Īccuracy of the localizer course width, in degrees.Ī code indicating the usability of the localizer signal in the back course sector. Note : The True North is the north point at which the meridian lines meet.Īccuracy of the measured angle between the localizer beam and True North at the localizer antenna. The measured angle between the localizer beam and True North at the localizer antenna. The measured angle between the localizer beam and Magnetic North at the localizer antenna.Īccuracy of the measured angle between the localizer beam and Magnetic North at the localizer antenna.