By providing "dry" air under pressure, moisture is never allowing moisture to enter the feed and transmission line system. In addition, the dry air provides a low dew point inside the waveguide making it difficult for moisture to form.
    In some cases, small systems can go without pressurization; however, they utilize a static dedicator. These desiccators (SD-001, and 002) function using the effects of the "vacuum" or breathing. As temperature and barometric pressures change the moist air is drawn into the feed system; however, it passes through the dessicator, which is attached near or directly to the feed.

  1. What is the difference between UHX and HPX antennas?
    Although both antennas have the same appearance from the outside, and both are dual polarized, there are other electrical performance parameters that differ between the two antennas. For the UHX antennas, the inside of the shield is fully lined with absorber material; absorber is also placed on the feed, and additionally the feed contains a special illuminator plate around the horn aperture that provides better pattern control. The UHX provides the best solution for pattern control in highly congested areas. The "red right or red left" option allows the superior pattern side of the antenna to be selected in the field.

  2. What struts and how many are with my antenna?
    The best method for understanding struts is located in the current catalog 38/page 96, as it indicates how many struts are included with each general type of antenna. The high wind bulletin 3522 also indicates the struts that are supplied with those series antennas. Also on pages 124, 125, and 126 additional information on struts is provided. SAP can also be utilized when exploding the BOM for any specific antenna.

  3. General trouble shooting:
    My antenna is down in gain, what's wrong?
    Troubleshooting should be politely pushed back to the customer; we sell components, not systems. There are many qualifying questions to be asked to help determine the root cause of the problem; and this comes with much field experience. Excessive "loss" levels such as -15, to -30 dB and beyond can usually be placed into 3 categories. They are antenna mis-alignment, cross polarization, or a moisture / water related issue. A mis-alignment to the first side lobe (FSLS First side lobe syndrome) is a common mistake that occurs to new installers. It also can show up during short paths (5 miles), and in high frequency antennas (18 ghz). Low signal strength generally happens when the antenna is locked on the first side lobe, and the main beam is not found. Following the simple guide lines in the SP20-21, and SP20-35 can help the installer regarding the alignment, and also help in understanding antenna performance. Offer to send email or fax copies.

    Cross polarization, during initial antenna alignment occurs when one antenna is horizontal facing one that is vertical. At best low signal level down -20 to -30 or more will be seen. In some cases test equipment is not capable of displaying such low values, and it would appear that the antenna is not functioning.

    Lastly, moisture can provide erratic performance results. It can cause VSWR performance problems as well as signal loss. Eventually it can reduce the signal to noise ratio all the way down to NO signal, or to the noise floor. Moisture or water can "sneak" into an antenna or transmission line causing attenuation. Aside from loss of signal, a common symptom of is signal fluctuation early in the morning or early in the evening. When the sun is at the horizon in either case. Large temperature fluctuations occur at this time and the dew point within the cable changes causing moisture to block the internal signal path. Water or moisture entry can be caused by;
    Pin holes in the outer conductor due to lightning
    Bullet holes
    Missing or pinched gaskets
    Fatigued or cracked outer conductor, due to scoring of the copper when knife cutting away the jacket of cable.
    Or when hanger spacing is far apart and the cable vibrates back and forth over a long period of time.
    A faulty dehydrator that is just passing moist air through the unit into transmission line.
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