RF Parameters

Gain is often incorrectly used as a one-stop measure of performance comparison between antennas, where the model with the highest gain figure represents the highest performance. As its alias suggests, gain represents the directivity of an antenna in the sense that performance is increased in the direction or axis of peak gain by decreasing performance in another direction or axis. Intuitively an antenna cannot 'create' extra energy, instead energy is focused in one direction or axis.

As such ...

One of the key parameters of any radio transmission component is VSWR or Return Loss (RL), which both measure how well the component is matched to other system components. Both are used somewhat interchangeably, with VSWR providing the measure as a ratio, and Return Loss providing the measure as a decibel figure.

In this article we aim to provide an introductory understanding of these concepts.

The Voltage Standing Wave Ratio (VSWR) is defined as the ratio of the maximum amplitude to the minimum ...

Polarisation is a crucial characteristic of an antenna, describing the orientation of the electric field vector as it propagates through space. In simpler terms, it describes the directional movement of the wave as it travels.

It is an important parameter to understand as wireless communication requires transmit and receive antennas to operate on the same polarity. Misaligned antennas can result in significant signal losses, potentially as high as 20 to 30 dB under worst case scenarios.

Most ...

Passive Intermodulation (PIM) has over the years become a critical parameter in component design due to new technologies in wireless communications allowing the use of higher transmit powers, wider bandwidths, and multiband / combination antennas.

PIM lowers capacity and data rate by limiting receive sensitivity, and as wireless usage grows pressure is on operators to squeeze the most out of their spectrum.

Passive intermodulation is a form of intermodulation distortion that occurs in passive ...

Tilting antennas is an important concept for applications like cellular and multipoint base stations that require targeting of their transmission to obtain greater control over each antennas coverage area.

There are two general types of tilting mechanisms, electrical, and mechanical. While at first glance the two seem similar there are significant differences. Conventional mechanical downtilting involves a rudimentary arm bracket to tilt the antenna body forward to focus the antenna boresight ...

Half-Power Beamwidth (HPBW), or more commonly referred to as just 'beamwidth' is a simple metric used to describe the dominant direction of radiation, which helps RF engineers quickly assess suitability based on required transmission/reception aperture.

Two figures are provided on all antenna datasheets; Elevation Beamwidth, and Azimuth Beamwidth, representing both vertical and horizontal planes. The terms vertical and horizontal can be used interchangeably, however it is important to note that E ...

Defining an antennas maximum input power rating is important to ensure that, as a sensitive electrical component, the antenna is not damaged by overvoltage.

Manufacturers often also specify a maximum input power figure to ensure that performance can be guaranteed under a known input power, the antenna may handle a higher power without damage but datasheet specification would be invalidated.

It is also necessary to append Per Port to the parameter, to eliminate ambiguity in the case of MIMO and ...

The following article serves to build an understanding about the antenna parameter known as Inter-Port Isolation. The parameter, sometimes referred to as Port-to-Port Isolation, is a simple metric that allows RF engineers to understand how well any two signals on a multiport or MIMO antenna are isolated from each other. Understanding the parameter is particularly important in the design of cellular and multipoint base stations as selecting antennas with high isolation reduces the complexity and ...

This article serves to build an understanding about the antenna parameter known as Front-to-Back Ratio (F/B Ratio). The objective of any directional transmission is to ensure the most amount of power is radiated in the forward direction, with the least amount to the rear of the antenna.

This parameter is used to help engineers designing directional systems (such as microwave or cellular broadcast sites) understand the potential interference radiated backwards by the antenna into collocated and ...

The following article serves to build an understanding about the antenna parameter known as Cross-Polar Isolation. Cross polar isolation is a metric specific to orthogonally polarised antennas, and while similar, is not the same as the more generic Inter-Port Isolation. Likewise, cross-polar isolation is similar but not equivalent to Cross-Polar Discrimination (XPD).

Cross-polar isolation strictly refers to the amount of power coupled between two orthogonally polarised ports of a dual-polarised ...

An antennas frequency range is one of its most fundamental characteristics, which describes the range of frequencies that the antenna is capable of operating on with an acceptable level of efficiency. Defining a set range is also important so all other parameters can be reported consistently. For example, quite often an antenna is capable of operating outside the set range, but its gain, VSWR, and radiation patterns may be volatile or non-constant. The width of a frequency range is also referred ...

The following article serves to build an understanding about the antenna parameter known as Cross-Polar Discrimination (XPD). Cross-polar discrimination is important for a low level of correlation between the orthogonally polarized propagation channels. Correlation generated by the antenna can negatively affect receive diversity and MIMO downlink performance of the system.

For cellular and multipoint antennas, Powertec recommend a minimum level of 8 to 10 dB within the relevant sector or ...