Mikko Komulainen

A Frequency Tuning Method for a Planar Inverted-F Antenna

A novel method is presented for electrically tuning the frequency of a planar inverted-F antenna (PIFA). A tuning circuit, comprising an RF switch and discrete passive components, has been completely integrated into the antenna element, which is thus free of dc wires. The proposed tuning method has been demonstrated with a dual-band PIFA capable of operating in four frequency bands. The antenna covers the GSM850, GSM900, GSM1800, PCS1900 and UMTS frequency ranges with over 40% total efficiency. The impact of the tuning circuit on the antennas efficiency and radiation pattern have been experimentally studied through comparison with the performance of a reference antenna not incorporating the tuning circuit. The proposed frequency tuning concept can be extended to more complex PIFA structures as well as other types of antennas to give enhanced electrical performance.

Frequency-tunable DVB-H antenna for mobile terminals

In this paper a frequency-tunable inverted F-antenna (IFA) for DVB-H reception is presented. The antenna is suitable for small mobile devices (40 mm times 90 mm times 10 mm). The operating frequency of the antenna is tuned with a varactor component. The varactor loads the IFA element and thus enables it to resonate at different frequencies. This kind of tunable narrowband antenna is suitable for DVB-H reception, since one channel in a bandwidth of 8 MHz is received at a time. The antenna presented in this paper can be compared with a frequency- tunable IFA of Ying (2005), presented in a recently published patent. This proves the potential of this kind of DVB-H antenna solution in commercial applications. A special advantage of the proposed antenna is that, since it can be located in a vertical position on the long side of the ground plane, as opposed to the work of Ying (2005), GSM antennas can be located in their optimal position at the upper part of the device.

Low-Sintering-Temperature Ferroelectric-Thick Films: RF Properties and an Application in a Frequency-Tunable Folded Slot Antenna

This investigation is one of the first steps toward the realization of low-cost, mass-producible, tunable antenna applications utilizing an integrated ferroelectric-thick film made of bariumstrontiumtitanate material. The dielectric properties of the electric-field-adjustable fired BST thick film are presented in the frequency range of 16 GHz. The key advantages of the material are high tunability (25% with 2.5 V/mum), compatibility with silver electrodes, and the ability to produce film thicknesses down to 25 mum. The utilization of the material is demonstrated by tuning the operating frequency of a folded slot antenna with an integrated variable capacitor. In addition, the impact of tuning on the antennas total efficiency and radiation pattern is experimentally studied through a comparison with the performance of a reference antenna not incorporating the varactor.

Capacitive Sensor Arrangement to Detect External Load on a Mobile Terminal Antenna

The feasibility of using a capacitive sensor to sense the proximity of an external load, especially a finger, to a mobile terminal antenna was experimentally studied using a PIFA-type antenna as one of the sensor’s electrodes. It was found that with the proposed arrangement it is possible to detect objects with permittivity close to that of body tissue or the conductivity level of aluminium and the size of a human finger at distances up to 15 mm.

Low-Loss and Wideband Package Transitions for Microwave and Millimeter-Wave MCMs

This paper presents high-performance flip-chip, through-substrate via and board-level BGA transition designs applicable in microwave and millimeter-wave multichip module (MCM) assemblies. Full-wave electromagnetic analysis was performed to achieve optimized transition structures. Interconnection test structures were fabricated in ceramic substrates and their performance was validated using on-wafer scattering parameter measurements. Both the flip-chip transition and the through-substrate via transition with a height of 800 mum exhibited return losses better than 25 dB and 20 dB, respectively, with low transmission losses up to 50 GHz. Furthermore, the wideband board-level BGA transition with a standoff height of 500 showed low insertion loss (< 0.5 dB) over a wide frequency range, from direct current (dc) up to 32.5 GHz.

Frequency-reconfigurable dual-band monopole antenna for mobile handsets

The main purpose of this paper is to present a method for electrically reconfiguring the operating frequency of a planar monopole antenna. In this method a tuning circuit composed of a RF PIN diode switch and two discrete passive components is built inside the antenna structure. This allows a DC control voltage to be brought to the diode switch along with the RF signal. Thus, this method of tuning does not require separate DC wiring, unlike commonly used structures proposed by Zachou et al. The method presented is demonstrated with a dual-band monopole antenna applicable in a mobile handset. The antenna has the capability of switching the lower band between the GSM850 and GSM900 frequency ranges with only a minor impact on the upper band. The upper band covers the frequency ranges of the GSM1800 and DCS 1900 telecommunication standards. Along with the antenna structure, the measured return loss and far-field gain are presented and discussed.

High performance vertical interconnections for millimeter-wave multichip modules

This paper presents high performance flip-chip and through-substrate via transition designs applicable in millimeter-wave single or multichip module assemblies. Full-wave electromagnetic analysis is performed to achieve an optimized transition topology. Interconnection test structures were fabricated in ceramic substrates and performance was successfully validated by on-wafer scattering parameter measurements up to 50 GHz. Both the flip-chip transition and the through-substrate via transition with a height of 800 /spl mu/m exhibited return loss better than 25 dB and 20 dB, respectively, with very low transmission losses within the entire measured band.

Frequency reconfigurable planar inverted-F antennas for portable wireless devices

In this paper, two approaches for frequency reconfigurable planar inverted F-antennas (PIFAs) are proposed and experimentally studied. In the first PIFA, an electrically-controlled frequency shift is achieved with a tuning circuit designed for the grounded PCB beside the antenna, while in the second PIFA the tuning circuit is integrated directly into the antenna with no separate DC wiring. The measured return losses, radiation patterns and total efficiencies of the antennas are presented and briefly discussed.

In-Band Frequency-Tunable Ceramic Planar Inverted-F Antenna (PIFA) Utilizing an Integrated BST-Based Variable Capacitor

The dielectric properties of low-sintering-temperature (LTCC) Barium Strontium Titanate (BST) thick film paste at high frequencies (0.8–5 GHz) are briefly presented. The utility of the BST paste was demonstrated by tuning the resonance frequency of a ceramic PIFA for mobile terminals operating at 2 GHz. The frequency tuning achieved can be used to compensate frequency detuning caused by the proximity of the user to the antenna. The impact of tuning on the antennas total efficiency and radiation pattern was experimentally studied through a comparison with the performance of a reference antenna not incorporating the varactor.

Switching a dual-band planar inverted-F antenna to operate in eight frequency bands

This paper describes the implementation of a dual-band planar inverted-F antenna that is electrically switched to operate in eight frequency bands. The eight bands are achieved by combining two frequency tuning concepts studied in our previous works. The complete tuning circuitry, consisting of three RF PIN diode switches and four passive components, is implemented without increasing the overall volume of the antenna. The antenna covers the 750-1080 MHz band with 25% and the 1560-2270 MHz band with 50% total efficiency margins.