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Multiband Antennas Versus Multibeam Antennas

Tamara Wilhite is a technical writer, industrial engineer, mother of two, and published sci-fi and horror author.

Introduction

Multiband antennas and multibeam antennas are very different devices, though their applications and potential uses often overlap. We’ll explain what multiband and multibeam antennas are and when their RF applications overlap.

What Are Multiband Antennas?

A multiband antenna is an antenna that works on many frequencies or “bands” This includes log periodic antennas, planar disk antennas and Vivaldi antennas. Wideband antennas and ultrawideband (UWB) antennas are by definition multiband antennas.

Most of these multiband antennas are directional. For example, a log periodic antenna can receive a wide variety of frequencies but the beam will only emanate from the tip of the antenna. Each of the elements in a log periodic antenna are for a single frequency, but the multiple antenna elements combine to create a multiband antenna.

A multi-band antenna, a 850-6500 MHz log periodic antenna designed by Kent Britain, WA5VJB.

A multi-band antenna, a 850-6500 MHz log periodic antenna designed by Kent Britain, WA5VJB.

What Are Multibeam Antennas?

A multi-beam antenna, multiple beam antenna or MBA antenna is simply one capable of creating more than one “beam”. It can create several, independent beams from a single aperture. Most multi-beam antennas are passive. They may take the form of beamforming circuits, phased array antennas that rely on phase-shifting methods, digital MBAs that are akin to software defined radios, and quasi-optical components. One common method is using digital channelizers or DCs to digitally assign bandwidth to each beam based on traffic demands.

Passive beamforming networks can be used to create omnidirectional antennas that are also able to work on a variety of wavelengths. This is in stark contrast to omnidirectional wheel antennas that can receive signals from any direction but can only receive a single frequency.

In theory, the multi-beam technology increases their range and efficiency so that it is comparable to that of a directional antenna. When applied to cell phone systems, they are able to send and receive data without the need for repeater stations.

Multi-beam antennas designs are often based on space division multiple access or SDMA techniques. This technology is already used to optimize the use of available spectrum. A multi-beam system allows them to cover up to 48 sectors, while the conventional SDMA technique lets them cover three sectors in a 360 degree coverage area. This allows the cell phone tower to serve many more customers with the same antenna without much more interference. They have a high signal-to-noise ratio. More importantly, they increase capacity and service quality over single beam (especially directional antennas) and dual beam networks.

Multi-beam antennas are increasingly rolled out for event-specific mobile coverage, dramatically increasing the number of 3G and 4G customers who can be served without increased latency or higher risk of dropped calls. However, the multi-beam antennas are typically installed at a lower elevation to maximize traffic and minimize interference.

Multi-beam antennas are being tested for use in 5G wireless communication systems, since they can support a high data transmission rate, spectral efficiency and signal-to-interference and signal-to-interference ratios. Multi-beam antennas are being adopted by communication satellite service providers to lower their overall cost of service, too. Satellite communications regularly use Digital Channelizer Beamformers or DCB.

These wideband antennas count as multiband, and the Vivaldi antenna is used to test multibeam antennas as well as cell phones.

These wideband antennas count as multiband, and the Vivaldi antenna is used to test multibeam antennas as well as cell phones.

Multibeam versus Multiband Antennas - How They Differ from Each Other

One way multi-beam antennas differ from multi-band antennas is that the multi-band antenna may generate many beams operating at the same frequency. Or it may produce several beams, each at a slightly different frequency. In short, multibeam antennas may or may not be multiband. However, multiband antennas are rarely multi-beam.

The Overlap between Multibeam Antennas and Multiband Antennas

Both multibeam and multiband antennas are being used in software defined radio or SDR. Multiband antennas are necessary for a software-defined radio to be able to receive a wide range of frequencies. A multi-beam antenna allows the software defined radio to send out multiple signals in different frequencies and directions.

Ultrawideband or multiband antennas are used to test software defined radios in the lab. These antennas can be directional, since they’re emulating a person on a cell phone or other signal generator. In this regard, multiband antennas are regularly used to test the performance of multibeam antennas.

© 2019 Tamara Wilhite