Daniel Nyberg

Characterization of multi-port Eleven antenna for use in MIMO system

The purpose of the present paper is to investigate the MIMO performance of the L-band multi-port Eleven antenna. Both a single- and dual-polarized lab model are investigated, both having 4 ports per polarization. The 4 ports per polarization are normally combined in a 180 deg hybrid to produce sum and difference patterns, but we investigate them here as individual ports in an antenna for a MIMO system. The embedded element efficiency, diversity gain and maximum available capacity of both models have been measured in a Bluetest reverberation chamber. The measured results show that the Eleven antenna is a flexible antenna that can be used with around 11 dB gain and arbitrary single or dual polarization in a Line-Of-Sight system and with 4 or 8 independent ports in a MIMO system, and it can easily be switched between these two modes by appropriate combination of the antenna ports.

User’s head and hand influence on the diversity performance of neutralized two-antenna systems for UMTS handsets

In this paper, we presented the influence of the userpsilas head and hand on the diversity performance of 0.1 lambda0 spaced PIFAs for UMTS handsets. If the DSG of the PIFAs of the handset positioned in free space is found to be very high (more than 8.5 dB), the DSG is severely degraded in the presence of the user. However, it seems that there is still an interest to add a second antenna for diversity purpose as the DSGs are around 3 dB in the UMTS Rx band. Further results with even more closely spaced PIFAs (down to 0.03 lambda0) will be presented at the conference.

THz smooth-walled spline horn antennas: Design, manufacturing and measurements

We describe a versatile and cost-efficient method for producing smooth-walled spline horn antennas for applications in THz radiometry. Specifically, the development of four different horns for radiometer receiver applications at frequencies 120, 183, 340 and 874 GHz is presented. General methods for efficient optimization of the spline profiles have been developed which enable the horn designs to be tailored to each application. All four designs display high Gaussicity (typically ~98%). Manufacturing methods based on numerical milling in splitblocks, lathing and drilling have been tested and compared. Milled splitblock horns with integrated receiver circuits (Shottky mixers in this case) allow for lower losses in the receiver system at the expense of higher cross-polarization levels. The radiation pattern of three designs at 183, 340 and 874 GHz have been measured using planar and rotational scanners.

Port balance, efficiency and correlation impact evaluation for MIMO compact multiantenna systems

The diversity gain and efficiency of two multiantenna prototypes have been evaluated with the reverberation chamber, which represents an advantageous measurement method due to its low time consumption and its high accuracy. The relation between port balance, efficiency, correlation and diversity gain has been analysed for the two compact multiantenna prototypes: Q-dime and 4-square, following a procedure according to Figure 1. Taking into account the good behaviour of both antennas regarding correlation (rho lower than 0.1), it can be said that the apparent DG difference of 0.8 dB between both prototypes is due to the amplitude unbalanced ports: since there is a branch much worse than the other three in case of 4-square patch, only the 3 good elements will be used in the selection combining, becoming a 3times3 system. The effective DG difference between the two structures is approximately 2 dB of which 0.8 dB is due the contribution of the port unbalance. The additional 1.2 dB increase is caused by the higher losses in the antenna elements, which is in accordance with the efficiency measurements.