The reliability of the system generally can be improved by the use of a second receiving antenna located at a different height (“space diversity”). Both antennas (primary and diversity) feed the receiver through appropriate switching devices. The space diversity improvement factor for vertically separated receive antennas is computed as: I = (7 x 10-5 x […]

The reliability of a system based on the computed fade margin is calculated based on the following equation (from Lenkurt) Undp = a x b x 2.5 x 10-6 x f x D3 x 10-F/10 where: Undp is the non-diversity outage probability. a is the terrain factor. b is the climate factor. f is the […]

The TAP fixed facility database includes a field for frequency diversity. If frequency diversity is not employed, set the “Diversity Frequency” field to zero (0). If frequency diversity is used, enter the second frequency in MHz. The improvement factor for frequency diversity is computed from the following equations, depending on the frequency of the system: […]

The TAP fixed facility database includes fields for digital fade margin values. These values can be used in addition to the computed thermal fade margin to compute a composite fade margin value. The additional fade margins included are: Dispersive Fade Margin (DFM) is the “contribution to outage that accounts for in-band distortion that can at […]

The climate factor used in the reliability calculation can be entered directly or computed from average annual temperature information. Lenkurt suggests the following values: .5 for gulf coast or similar hot, humid areas. .25 for normal interior temperate or northern areas. .125 for mountainous or very dry areas. The climate factor can be computed using […]

The terrain and humidity factor used in the microwave reliability calculation can be entered directly, or the value can be computed from humidity and terrain roughness information. Lenkurt (1970) suggests the following values: 4 for very smooth terrain, including over water. 1 for average terrain, with some roughness. .25 for mountainous, very rough, or very […]

Rain Attenuation The rain attenuation due to rainfall can be entered directly or computed by three different methods (see Ryde & Ryde, Medhurst, and CCIR). When you direct TAP™ to calculate rain attenuation, you will enter a rainfall rate (in either inches or millimeters per hour) and the portion of the path affected by rain […]

Several types of calculations are used to make microwave link reliability predictions. One of these is the microwave path free space loss. The free space loss is computed based on the path length and frequency using the equation: A = 96.6 + 20 LOG(F) + 20 LOG(D) where: A is the attenuation in dB. F […]

There is a great deal of confusion when engineers, technicians, and equipment salespersons talk about units of antenna gain and field strength. This FAQ discusses units of gain and field intensity and explains how to convert between some of these units when appropriate. Units of Antenna Gain While field strength at any location is independent […]

Using the 3D Display Module, it is straightforward to export path profile and area coverage study information to a KML file that can be displayed in Google Earth, ARCGis, GlobalMapper, and other mapping programs. TAP™ offers one-button export of KML files to Google Earth.  For large area coverage studies using Tile geometry, it is recommended […]