Jonathan Mayer

MIMO OFDM radar system for drone detection

This paper presents a system setup based on MIMO OFDM radar that can be used for drone detection and detection of unpiloted aerial vehicles (UAVs) in general. In recent years UAVs have become more and more popular not only for commercial use but also as a private gadget. However, these drones can also be misused as a weapon by criminals, spies and terrorists. Therefore many research is done to be able to detect drones and prevent further harm. One possible approach is radar that has already been used successfully in automotive and military applications and offers many advantages like weather and daylight independent operation. It is also possible to detect drones that are emitting no electrical or optical signals. However, there are still many challenges that have to be solved before the implementation of reliably operating systems. This paper presents a system approach based on MIMO OFDM radar that can be used to survey large areas simultaneously and detect flying drones. Additionally, verification measurements with a drone in a real world scenario are presented demonstrating the successful operation of the system.

A compact pattern reconfigurable antenna utilizing multiple monopoles

A reconfigurable antenna for optimal radiation patterns used for automotive urban scenarios is proposed in this paper. The antenna is anticipated to radiate in the best sub-channels obtained from a channel simulation. The antenna consist of two serially fed monopoles placed on one substrate. The pattern switching is realized by changing the phase of the feeding signal. Thus, two directional patterns are realized, whereby the first is in and opposite the driving direction and the second is shifted by 90° in azimuth, thus orthogonal to the driving direction. The chosen frequency of operation is 2.45 GHz. As a proof of concept two prototypes of the antenna, one utilizing p-i-n diodes and one using MEMS (micro-electro-machanical switch) as switching elements have been fabricated and measured. The maximum gain achieved is about 5 dBi. The measurement results show that only slight improvement is achieved if MEMS are used instead of p-i-n diodes.

A trident like antenna with reconfigurable patterns for automotive applications

Within the scope of this work, a reconfigurable antenna for automotive applications has been developed and constructed. The concept of planar parasitic array has been chosen due to its size. Furthermore, as an improvement to this concept, the parasitic elements were also used as active radiators. The antenna realizes four reconfigurable patterns that cover the angular regions in and against the driving direction as well as those orthogonal to the driving direction. Additionally a DC feeding network using metamaterials to decrease its influence on antenna characteristics is proposed. The measurement results match the simulated results and maximal gain of about 8.5 dBi is obtained.

Channel Measurement Based Antenna Synthesis for Mobile Automotive MIMO Communication Systems

In this paper a multiple input multiple output (MIMO) radio channel measurement system is presented that utilizes several software defined radio (SDR) platforms at the transmitter and at the receiver. The system hardware buildup and its calibration technique are presented. The channel measurement results are afterwards exploited for a special antenna synthesis method that was already proofed by raytracing channel simulations. The antenna synthesis method is applied to a mobile single and to a mobile multiple channel receiver. The resulting synthesized antenna systems are evaluated in terms of antenna radiation patterns and the corresponding channel capacities. The results reveal the superiority of synthesized antenna systems compared to conventional omnidirectional antenna systems in the considered urban street scenario. Moreover, the findings from the antenna synthesis based on dynamically measured MIMO radio channels confirm the results from the raytracing channel simulation based antenna synthesis.