Path obstructions are also a possibility but are rare occurrences in today's times. Examples of trees growing in the path, or leaves blocking a path from spring into summer. Buildings erected after a path was put in are also a possibility.

    Absorber material that falls from the inside of a shielded antenna could fall onto the feed in front of the window causing the signal to fail.

    Other less signal issues such as -3 to -15 could be the same as described above. In addition incorrect feed frequency or feed length can cause low signal levels. Severely damaged or bent feeds from falling ice can also place a feed out of the focal length. Active paths can also be in a "fade" and thus low signal is temporary and may return. A broken feed guy wire can also pull a feed off the center orientation-reducing signal.

  1. What are the operational and installation temperature limits of my antenna?
    The operational range for microwave antennas are -50C to 70C (-58F to 158F) and meet the requirements of EIA/TIA Standards 222E and 195C. (Page 49 of Cat. 38). Each individual or company determines installation limits.

  2. Can my antenna work out of band? (VSWR)
    Antennas are designed and manufactured to certain specifications. These typically fall within guidelines of market bands (at the time of initial antenna development). The factory will VSWR tune feeds beyond the upper and lower frequency (start / stop freq.) by 20 MHz. For individual requests, there are no performance guarantees. Each feeds needs to be VSWR swept across the required "new" frequency band to determine its performance. Typically the VSWR level rapidly rises out of band and poor performance can be expected.

  3. What feed does this antenna go into to make what antenna?
    Querying a "where used" in SAP may help narrow the search

  4. What is the feed focal length?
    This is the "optimum" positioning of the feedhorn to the reflector to achieve the maximum efficiency and best overall performance. This length is predetermined and no field adjustment is required. In cases where many different size reflector and feeds are available, installers may need to "pair up" the two. The "theoretical" dimensions are listed below. As actual readings are not practical to measure due to the exact reference points, the general points are the feed window, and feed mounting plate.
    Standard Antennas
    Size dia Focal length F/D
    2ft 29" (228.5mm) .375
    4ft 18" (457mm) .375
    6ft 27.5" (698.5mm) .382
    8ft 35.8" (909mm) .298
    10ft 35.8" (909mm) .298
    12ft 48" (1219mm) .333
    15ft 60" (1524mm) .333
    Focal Plane Antennas
    Focal length F/D
    n/a n/a
    12" (305mm) .250
    18" (457mm) .250
    24" (609.5mm) .250
    30" (762mm) .250
    36" (914.5mm) .250
    45" (11434mm) .250

    By using these values an installer should be able to sort feeds. Note, that PAR, and PARX series feeds for 6 ft and 8 ft antennas are focal plane type NOT standard reflectors.

  5. What is regulatory compliance?
    Government bodies in each country set up special radiation pattern requirements. These categories set certain electrical requirements that all manufactures must meet in order to have their customers license an antenna in areas regardless of frequency congestion. Typical guidelines include frequency, beam width, front to back ratio, and general patterns. The listing for current requirements are found next to each antenna listed in the catalog.
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