Antenna & Radio Data Files

Microwave Antenna Data Files

A microwave interference analysis requires horizontal radiation pattern envelopes for the four polarization combinations (HH, VV, HV and VH). The same information is required for point to multipoint applications where the base antenna has a fixed orientation. This data is contained in separate antenna data files one for each antenna model. These files start as ASCII files following a standard format used by most antenna manufacturers and converted to a binary format inside the Pathloss program. The file contains the basic antenna specifications and the radiation pattern envelopes and can also include vertical radiation pattern data.
At present, the program includes ASCII and binary antenna files for approximately 3500 microwave antenna models.

Microwave Radio Data Files

In order to calculate the degradation of a digital receiver threshold in the presence of interfering signals of any bandwidth and modulation, the following parameters are required:

10-6 BER threshold
threshold to interference ratio (T-I) for a like modulation and capacity cochannel interferer
channel bandwidth
3 dB bandwidth of the transmit spectrum

The following curves will be used if available:

transmitter spectrum versus frequency
T-I ratio versus frequency for a like modulations and capacity interferer
T-I ratio versus frequency for a CW interferer
T-I ratio versus frequency for interferers with different modulations and capacities
Interference reduction factor versus frequency for a like modulation and capacity interferer.
Interference reduction factor versus frequency for interferers with different modulation and capacities

The above data and other general specifications is contained in radio data files. These files start as ASCII files and are converted to a binary format inside the Pathloss program. The binary file conversion will create default transmit spectrum and receive selectivity masks which will be used to determine the filter improvement if the required curves are not available.

At present, the program includes ASCII and binary radio data files for approximately 120 digital radio models from major manufacturers.

Threshold-to-Interference (T-I) Ratio Definition

The T-I ratio is defined as the ratio of to the desired to the undesired signal power that degrades the digital receiver 10-6 BER threshold by 1 dB. The advantages of T-I are that the difference in thresholds, due to bit rate, modulation technique, and noise figure, are all taken into account.

Measurement of T-I for a digital radio is accomplished by fading the receiver to the 10-6 BER threshold point. The signal level is then increased by 1 dB and interference is injected until a BER of 10-6 is again achieved on the link. The ratio of the initial power level of the desired received signal to the interference power is the T-I ratio. Note that this value will be different for different interferers, especially if the interfering signal is offset in frequency from and/or has a wider spectrum than, the victim receiver's bandwidth.

VHF-UHF Antenna Data Files

Vertical and horizontal radiation patterns are required in an receive signal area coverage analysis and in a point to multipoint application where the base station antenna has a fixed orientation. This data is contained in separate VHF-UHF antenna data files one for each antenna model. These files start as ASCII files following the format proposed by the NSMA and are converted to a binary format inside the Pathloss program. The file contains the basic antenna specifications and the horizontal and vertical radiation pattern. Unlike the microwave antenna patterns which are envelope patterns, the patterns for the VHF-UHF antennas are typical patterns.

The program includes approximately 1500 VHF-UHF antenna data files for several manufacturers in the frequency range 50 to 2500 MHZ.

Last Update: 08/06/99