Microstrip phased-array antennas : a finite-array approach

XII+195hlm.;24c

Increased operational range for implantable UHF RFID antennas

This paper discusses the main design challenges of implantable UHF RFID antennas in lossy environments. A novel cylindrical implantable antenna concept is presented. The proposed antenna shows good performance inside lossy environments, like a human body. The RFID tag is able to work in a range up to 3 m for implantation depths in the range of 1 - 2.5 cm. A basic demonstrator with RFID integrated circuit (IC) was manufactured and tested in order to prove the proposed design strategy

Miniaturization of robust UHF RFID antennas for use on perishable goods and human bodies

Design guidelines for electrically small and robust UHF RFID antennas are derived for operation in complex environments, such as perishable goods (e.g. meat and milk) or human bodies. A prototype UHF RFID antenna tag with an embedded Integrated Circuit (IC) is developed and tested in a RFID system. Water and meat tissue are used as environments. The obtained range of operation appears to be very robust. Measurements show a range of 3 m for the meat case and 2.5 m for a water environment at 868 MHz

On the pattern synthesis for focal plane arrays using the iterative method optimization

This paper presents a general technique for the synthesis of the antenna radiation pattern which does not require the calculation of derivatives or calculation of the Fourier transform. A new alternative formulation will be presented for the intersection method. The main concept of this method is to find a common point of many different sets using the projection matrix algorithm. The method with necessary amendments is then employed for focal plane arrays to find the proper excitation coefficients which fits the pattern into the desired mask. The method is found to be faster than the gradient search algorithm which is commonly used for beam synthesis. Numerical results for a focal plane array are shown and advantages discussed

Antenna-on-chip integration in mainstream silicon semiconductor technologies

\u3cp\u3eThe mobile data traffic is rapidly increasing. Several bands have been identified in the millimetre-wave spectrum that could be used to support the expected average smartphone traffic of 6.8 GB in 2021. Due to the short wavelength at those frequencies, the antennas can and should be integrated together with the front-end electronics. This paper provides an overview of integration approaches developed at the Centre for Wireless Technology Eindhoven. Moreover, it provides a comparison of the presented concepts in terms of performance and relative cost. The conclusion is drawn that in-package antennas seem to be the best integration approach for frequencies considered for 5G and a general guideline is provided for frequencies beyond 5G.\u3c/p\u3

Guidelines for millimeter-wave antenna measurements

\u3cp\u3eThe characterization of physically small antennas in the millimeter-wave range has proven to be a challenge. Several research groups have developed new antenna measurement systems to be able to characterize millimeter-wave antennas. These measurement systems mainly focus on the establishment of a well-defined connection between test equipment and the antenna-under-test (AUT) for radiation pattern measurements. However, uncertainties affecting the measurement results are not always well understood. We have investigated the effect of misalignment, the effectiveness of an anechoic environment for frequencies up to 90 GHz and the impact of spurious radiation of the probe.\u3c/p\u3

Broadband material characterization method using a CPW with a novel calibration technique

When combining contactless power and data transfer, antennas are often placed near magnetic materials with unknown RF properties. While permittivity measurement methods for dielectric materials at RF frequencies are well established, methods for permeability measurement are relatively scarce and often cumbersome. We propose a versatile and easy-to-use method that is applicable to both dielectric and magnetic materials, which uses a coplanar waveguide structure to measure the complex permittivity and permeability in the 1–16 GHz range. We combine the Nicolson–Ross–Weir algorithm with a robust root selection and a conformal mapping method to extract the permittivity and permeability from the measurement data. Moreover, we propose a novel calibration method that uses a single reference dielectric to increase the accuracy of the measured permittivity significantly, even when measuring magnetic materials

Theoretical and experimental performance of a wideband wide-scan-angle rectangular waveguide phased array (for radar application)

A wideband wide-scan-angle phased array using rectangular waveguides as radiating elements is described. The design, theoretical performance, and experimental verification of the wideband phased array are presented. The verification of scan performance was performed on a 15*15 element array and included element pattern and mutual coupling measurements. The array will be applied in a multifunction active phased array radar codenamed EXPAR. Oepn-ended waveguide elements were preferred above printed circuit dipole and stripline notch radiators because of their accurately predictable performance and good cross polarization behavior in an array environment. A unique feature that favors the waveguide element is its highpass filter characteristics due to the cutoff frequency of the waveguide modes

5G millimeter-wave beam adaptation for indoor moving users

\u3cp\u3eThis paper presents the results of a preliminary measurement campaign on beam adaptation for indoor moving users, comparing the path loss on a typical modern office floor and a lab floor. The performance of a static user beam is compared to that of an optimized user beam for the scenario of a user walking through a corridor. Results show that beam optimization is most beneficial when a line-of-sight is present. The gain of beam optimization decreases when the number of reflections required to establish a path increases. It is shown that the average path loss after beam optimization is lower on the office floor than on the lab floor that has a similar layout, but mainly metal instead of glass walls. The presented results show that glass walls on the office floor provide low-loss paths via reflections, while a glass window at the lab floor blocks paths.\u3c/p\u3