Microwave links are a key element of communications systems ranging from broadcasting and mobile networks to private networks because they transmit large amounts of data efficiently. While they provide multiple benefits, proper testing during deployment, installation, and maintenance are necessary to overcome some of the challenges associated with microwave links, such as the need for line of sight.

What is a Microwave Link?

A microwave link transmits data from one fixed location to another using the microwave spectrum. They have been used for more than 80 years and continue to grow in deployments due to IoT, 5G, and the overcrowding of the RF spectrum.

One reason microwave links are used in so many emerging applications is that they are broadband, so large amounts of data can be transmitted at high speed. Other main features of microwave links include high spectral efficiency, automatic transmit power control, and adaptive coding and modulation. Microwaves are also able to penetrate rain, fog, and snow, so transmission is typically not adversely affected during poor weather conditions.

Microwave Link Considerations

A microwave link is either point-to-point or point-to-multipoint. It typically features a radio unit and a parabolic antenna. A clear line of sight is required between two antennas for signals to be successfully transmitted. Microwave beams are pointed directly at the receiving antenna. This allows nearby microwave systems to use the same frequencies without causing interference, unlike signals operating at lower frequencies.

In addition to 5G, microwave links are used extensively in 4G LTE and other legacy mobile networks. Broadcasters, government agencies and corporations in need of networks with high-performance, flexibility, fast deployment, and low operating costs also rely on microwave networks.

As the microwave signal travels from a radiating source, its energy scatters over a larger surface area, which is referred to as the Fresnel zone. The result is that the signal strength becomes weaker. Those responsible for deploying, installing, and maintaining wireless networks must factor this into consideration.

Necessary Testing

Microwave links can only be established provided the antennas work efficiently. If the microwave backhaul antennas are not tested for their gain, return loss, and VSWR, the performance of the microwave links could be severely hindered.

For these reasons, comprehensive testing must be conducted on microwave links. Among the key tests that need to be performed are:

Receive Signal Level — A measurement of the actual received signal level presented to the antenna port of a radio receiver from a remote transmitter.
Receiver Sensitivity — A measurement of the weakest RF signal level that a microwave radio needs to receive to demodulate and decode a packet of data without errors.
Antenna Gain — The ratio of how much the RF signal is boosted by an antenna over a specified low-gain radiator.
Transmit Power — A measurement of the RF power from transmitter antenna port measured in dBm, Watts or milliWatts.
Effective Isotropic Radiated Power (EIRP) — A calculation used to estimate the radiated output power of an isotropic antenna.
Signal-to-noise Ratio (SNR) — A measurement of the ratio in dB between the signal level received and the noise floor level for a designated signal.

Test Solutions

Anritsu has test solutions that can be used to ensure the proper deployment, installation, operation, and maintenance of microwave links.

Field Master™
The Field Master Pro field portable RF spectrum analyzer delivers the highest levels of RF performance available in a handheld, touchscreen spectrum analyzer, with an optional real-time spectrum analyzer, cable and antenna analyzer, interference hunting, and 5G/LTE base station testing. It is specifically designed to meet the test challenges of a full range of wireless technologies in use today.

Ultraportable Spectrum Master™
The Spectrum Master ultraportable spectrum analyzers are USB-powered and controlled from a Windows-based device, making them uniquely flexible for lab, manufacturing, or field use. The first solutions of their kind to provide continuous coverage to 170 GHz, they deliver best-in-class price/performance unmatched by traditional benchtop instruments.

Spectrum Master™
Spectrum Master handheld spectrum analyzers deliver high frequency/level accuracies and smart, intuitive features. As the de facto industry standard, Spectrum Master provides measurement flexibility in a lightweight, rugged package. With frequencies from 9 kHz to 20 GHz, Spectrum Master is ideal for spectrum clearing and monitoring, interference hunting and mitigation, and general-purpose measurements.

Site Master™
The Site Master handheld cable and antenna analyzer is for field installation, troubleshooting, and maintenance of coaxial and waveguide systems. Its internal architecture includes a four receiver, fully reversing, 2-port cable and antenna analyzer to provide high-resolution distance-to-fault (DTF) measurements. VNA and vector voltmeter (VVM) options extend the instrument’s powerful capabilities.

Vector Network Analyzers
The ShockLine MS46131A 1-port series, 1 MHz to 43.5 GHz, is ideally suited for making antenna measurements used in Microwave Links. E-band frequency options for the ShockLine MS46522B VNA offers tethered source and measurement modules to bring a new level of performance, cost, and convenience to banded millimeter-wave (mmWave) measurements used for testing microwave backhaul in 5G.