TMW Frequently-Asked Questions
(And Answers)

  1. What reflectors can be split?
    Some solid reflectors can be "cut" in half to allow ease of shipments in confined cargo containers such as ship holds, rail cars or aircraft. They also allow easy movement in elevators, and through hallways to rooftops on buildings, or other site-access situations where roads cannot support large transportation vehicles.

    Split reflectors are known as the "KD", or knockdown, series. The solid, spun reflectors are split, then assembled to ensure proper alignment; then taken apart, and painted and readied for shipment. Reflectors are reassembled in the field (on site) through the use of a 2" wide strip that overlaps the seam or cut. Half of the strip is permanently riveted to one side or half of the reflector. The other half is aligned then bolted together.

    Currently all (solid) 15ft (4.5m) reflectors are split. Most 12 ft. (3.7m) reflectors are split too. Splits are an added cost option for 8 ft. (2.4m) and 10 ft. (3.0m) diameter reflectors. "Split" reflectors are NOT available for 6 ft (1.8m) and smaller diameter reflectors.

    Knock-Down Parabolic series grids (KP), or Gridpak antennas are shipped in pieces and require complete assembly element by element. Pre-assembled units are currently not offered. Assembly is possible through Andrew Field Services.

  2. Are feeds interchangeable?
    Feeds for most terrestrial microwave (TMW) antennas physically fit in the mounting hole in the center of the reflector. However, more information is required before this should be attempted. Andrew Corporation guarantees antenna performance parameters when shipped complete from the factory. Changing components (even when they physically fit) in the field does not necessarily guarantee new antenna performance values. Frequency, antenna size, and existing equipment are the three considerations in question.

    As frequency increases (i.e. a change from 6 GHz to 10 GHz) the manufacturing tolerances also decrease. This means that if you are attempting to move "up" the band by replacing the feed only, the reflector, and some mount components may not be suited to guarantee specifications. And of course, focal lengths of feeds are different; i.e., 6 ft. and 8 ft feeds are not interchangeable.

    Generally any changes made to an antenna in the field are the responsibility of the customer or end user.

  3. Can I repair a feed in the field; can I send it in for repair?
    Minor repairs to feeds such as air pressure leaks can (and should) be field repairable. As moisture in the waveguide is probably the number one cause for loss of microwave signal after the initial installation has been completed.
    Waveguide
    Blown feed windows are fairly simple to repair in the field for "most" microwave feeds. Repair kit 39900 can be sent to the customer in most applications. Contact TMW product line regarding specific feed applications. General leaks due to poor soldering at flange locations can be repaired in the field. These types of pinholes can be filled with a good metal filler or epoxy (such as pacer loctite material). Other bent or damaged feed situations should be reviewed by submitting a photo to the product line, or the factory for estimates of repair prior to shipment back to the factory. (Requires RMA#)
    Coax
    Coax feeds are more difficult to repair than that of waveguide types. Air leak caused by a cracked Plexiglas window in should NOT be attempted in the field. Although the "mechanics" are not that difficult, there are sensitive tuning screws that control the VSWR performance levels of the feed.
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