Millimeter wave radar systems offer several advantages such as the combination of high resolution and the penetration of adverse atmosphere like smoke, dust or rain. This paper presents a monolithic millimeter wave integrated circuit (MMIC) transmitter which offers four channel beam steering capabilities and can be used as a radar or communication system transmitter. At the local oscillator input, in order to simplify packaging, a frequency tripler is used to multiply the 76.6 - 83.3 GHz input signal to the intended 230 - 250 GHz output frequency range. A resistive mixer is used for the conversion of the intermediate frequency signal into the RF domain. The actual beam steering network is realized using an active single pole quadruple throw (SP4T) switch, which is connected to a integrated Butler matrix. The MMIC was fabricated in a 35 nm InGaAs mHEMT process and has a size of 4.0 mm × 1.5 mm
A millimeter-wave spectroscope for the detection of triatomic gases has been constructed and characterized for frequencies between 230 and 325 GHz (H-band). The achieved results demonstrate a high sensitivity and low threshold detection. A circular lensed horn antenna transmits millimeter- waves into a gas-filled vacuum tube and excites triatomic gas molecules to a higher energy level, if the rotational resonance frequency of the molecule matches with the excitation frequency. At the other end of the tube a second lensed horn antenna receives the propagated electromagnetic wave and the millimeter-wave power is measured by a heterodyne receiver. By sweeping the radiated transmit frequency, the molecules' specific absorption can be detected. The measured absorption results are superimposed by standing wave effects within the tube. To eliminate the standing wave effects, spectroscopy on the basis of rotational spontaneous millimeter-wave emission was examined. This kind of spectroscopy decouples the transmitted from the received signal, whereby independent excitation and detection of the molecules are realized. The use of additional absorbers at the end of the gas tube decreases the decay time of the radiated wave inside the gas cell. In this paper, the detection of spontaneous emission of triatomic gas molecules with the use of a pulse-controlled transmitter and receiver is shown. Optimizations improved the stability and reproducibility of the measurements, and the detection threshold of nitrous oxide could be decreased to a ratio of 1/400. Furthermore, the implementation of a differential measurement method reduces the measurement time by a factor of 150 and simultaneously decouples of environmental influences.
The use of millimeter-waves for imaging purposes is becoming increasingly important, as millimeter-waves can
penetrate most clothing and packaging materials, so that the detector does not require physical contact with
the object. This will offer a view to the hidden content of e.g. packets or bags without the need to open
them, whereby packaging and content will not be damaged. Nowadays X-ray is used, but as the millimeter-wave
quantum energy is far below the ionization energy, it is less harmful for the human health. In this paper we report
an active millimeter-wave imaging tomograph for material analysis and concealed object detection purposes. The
system is build using in-house W-band components. The object is illuminated with low-power millimeter-waves
in the frequency range between 89 and 96GHz; mirrors are used to guide and focus the beam. The object is
moved through the focus point to scan the object pixel by pixel. Depending on the actual material some parts
of the waves are reflected, the other parts penetrate the object. A single-antenna transmit and receive module
is used for illumination and measurement of the material-specific reflected power. A second receiver module
is used to measure the transmitted wave. All information is processed for amplitude and phase images by a
computer algorithm. The system can be used for security, such as detecting concealed weapons, explosives or
contrabands at airports and other safety areas, but also quality assurance applications, e.g. during production
to detect defects. Some imaging results will be presented in this paper.
At this paper we report on a W-band direct detection radiometer cascading a single-pole four-throw switch with
integrated 50 Ω load as a reference noise source, a 3 x 20 dB low-noise amplifier chain, and a broadband Schottky-diode
detector. All components are designed and fabricated in 100 nm metamorphic high electron mobility transistor
(mHEMT) technology and use waveguide packaging. By using 2 channels of the switch module the Dicke-principle is
implemented to drastically reduce the inherent amplifier noise. The multi-throw switch insertion loss is less than 3.5 dB
on the chip level and 4.4 dB on the module level. The entire W-band direct detection radiometer chain is also integrated
on a single chip and packaged into a waveguide module, which was successfully tested and is now ready for system
Millimeter-wave monolithic integrated circuit (MMIC) technology is now widely recognized as a key to many modern applications in safety and security, ranging from near and far-field imaging and sensing to non-invasive material inspection. In this paper, we apply our
state-of-the-art MMIC technology to the analysis of gaseous media by spectroscopic techniques. The paper presents recent developments of amplifying and frequency-translating MMICs based on metamorphic HEMT technology and their application to the spectroscopic analysis of the frequency range from 250 to 330 GHz, including the important absorption line of water around 321 GHz.
Recent advances in MMIC-based solutions dedicated to imaging and sensing applications in the atmospheric windows located around 140, 200 and 300 GHz are presented. The MMICs comprise the individual components of a typical architecture of heterodyne analog frontends, and their combination into MMICs performing several functionalities or with full receiver capability. We discuss low-noise amplifiers up to 300 GHz, frequency multipliers and mixers operating up to 300 GHz, a power amplifier MMIC achieving more than 11 dBm of output power at 140 GHz, and a 200 GHz multi-functional, heterodyne receiver MMIC driven by a subharmonic local oscillator signal with low power requirements.
We report on MMIC-based analog frontend components for imaging radar and radiometry at high millimeter-wave frequencies. The MMICs are realized in our metamorphic HEMT technology. In W-band, the focus is on analog frontends with multi-pixel capability. A compact four-channel receiver module based on four single-chip heterodyne receiver MMICs achieves a noise figure of 4.2 dB and a conversion gain of 7 dB. A W-band five-to-one switch MMIC with less than 3.5 dB insertion loss addresses four antenna ports and uses an integrated reference termination for pixel normalization. Both components operate in a frequency range from 75 to 100 GHz, making them suitable for broadband imaging systems with high geometrical resolution. After an overview of MMIC amplifier performance over the entire millimeter-wave frequency range, we present a chip set for imaging radar at 210 GHz, comprising linear and frequency-translating circuits.