MICROWAVE MEASUREMENTS

Microwave Measurement devices

Network Analyzer

Spectrum Analyzer

Power Meter

RF Network Analyzer

RF Network analyzers are used to measure components, devices, circuits, and sub-assemblies. An RF network analyzer will contain both a source and multiple receivers.

An RF network analyzer looks for a known signal, i.e. a known frequency, at the output of the device under test, since it is a stimulus response system. With vector-error correction, network analyzers provide much higher measurement accuracy than spectrum analyzers.

Scalar Network Analyzer

As the name indicates, a scalar network analyser or SMA is a form of RF network analyzer that only measures the amplitude properties of the device under test.

Used to plot the response of a filter.

Filter Response using SNA

Vector Network Analyzer

The vector network analyzer, VNA is a form of RF network analyzer widely used for RF design applications. A vector network analyser is a test system that enables the RF performance of radio frequency (RF) and microwave devices to be characterised in terms of network scattering parameters, or S parameters

The key element of the vector network analyzer, VNA, is that it can measure both amplitude and phase.

Spectrum Analyzer

By contrast to RF network analyzers, spectrum analyzers are normally used to measure the characteristics of a signal rather than a device.

The parameters measured may include: signal or carrier level, sidebands, harmonics, phase noise, etc. They are most commonly configured as a single channel receiver, without a source. Because of the flexibility needed to analyze signals, spectrum analyzers generally have a much wider range of IF bandwidths available than most RF network analyzers.

Spectrum analyzers can be used for testing networks such as filters. To achieve this they need tracking generator. When used in this way, spectrum analyzers can be used for scalar component testing (magnitude versus frequency, but no phase measurements).

Handheld Spectrum Analyzers

Handheld Spectrum analyzers are portable and easy to use. These RF analyzers operate both standalone as handheld devices, plus they interface via USB cable to a PC running more sophisticated data acquisition and analysis software.

Features

Graphics LCD 128×64 pixels

Spectrum Analyzer mode with Peak Max and Hold, Normal, Overwrite and Averaging modes.

High capacity Lithium-ion polymer internal battery for 16hs+ of continuous run, rechargeable by USB.

Can interface to Windows PC running data acquisition and analysis software.

Wide band coverage includes: all popular sub-1Ghz ISM bands, 2.4x GHz (Wi-Fi, bluetooth, Zigbee), with maximum frequency reaching to 2700 MHz.

Satellite Television

Satellite television, like other communications relayed by satellite, starts with a transmitting antenna located at an uplink facility. Uplink satellite dishes are very large, as much as 9 to 12 meters (30 to 40 feet) in diameter.

The transponder 'retransmits' the signals back to Earth but at a different frequency band (a process known as translation, used to avoid interference with the uplink signal), typically in the C-band (4–8 GHz) or Ku-band (12–18 GHz) or both.

Basics of Satellite Communication

Satellite TV uses a special type of video file compression standardized by the Moving Picture Experts Group (MPEG). With MPEG compression, the provider is able to transmit significantly more channels.

With MPEG-2, the TV provider can reduce the 270-Mbps stream to about 5 or 10 Mbps

Satellite Dish

A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consists of a parabolic (bowl-shaped) surface and a central feed horn.

The central element in the feed horn is the low noise blockdown converter, or LNB. The LNB amplifies the radio signal bouncing off the dish and filters out the noise (radio signals not carrying programming). The LNB passes the amplified, filtered signal to the satellite receiver inside the viewer's house.

Testing of Microwave Ovens

A microwave oven, often shortened to microwave, is a kitchen appliance that heats food by bombarding it with electromagnetic radiation in the microwave spectrum causing polarized molecules in the food to rotate and build up thermal energy in a process known as dielectric heating.

A microwave oven heats food by passing microwave radiation through it. Microwaves are a form of non-ionizing electromagnetic radiation with a frequency higher than ordinary radio waves but lower than infrared light. Microwave ovens use frequencies in one of the ISM (industrial, scientific, medical) bands, which are reserved for this use, so they don't interfere with other vital radio services.

Microwave Oven Radiation

A Federal standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts (mW) of microwave radiation per square centimeter at approximately 2 inches from the oven surface.

This limit is far below the level known to harm people. Microwave energy also decreases dramatically as you move away from the source of radiation. A measurement made 20 inches from an oven would be approximately one one-hundredth of the value measured at 2 inches.

Radiation Injuries

The radiation emitted would interfere with electronic devices like pacemakers.

The FDA received reports in the past of serious skin burns or scalding injuries around people's hands and faces as a result of hot water erupting out of a cup after it had been over-heated in a microwave oven.