A volumetric W-band near-field (NF) antenna measurement system is presented and evaluated. The system supports measurements at arbitrary locations within the measurement volume with high positioning accuracy together with corresponding field transformations. The measurement performance of the system is carefully investigated with respect to accuracy and efficiency, e.g., by a comprehensive evaluation of room scattering and by laser scanner measurements. The fast irregular antenna field transformation algorithm (FIAFTA) is utilized to perform the necessary NF to far-field transformations. Due to the flexibility of FIAFTA, so-called nonredundant planar measurements become possible, which overcome the classical half-wavelength sampling requirement entailed by the fast Fourier transform-based transformation approaches. Thus, with a time-factor of about 35, accelerated planar measurement results are achieved by projecting angularly uniform sample grids on the minimum sphere around the antenna under test (AUT) onto the measurement plane, resulting in irregularly thinned planar measurement grids. The error levels between two completely independent measurements employing full and thinned grids are found at a level below -40 dB. Moreover, such measurements allow decreasing mutual interactions between the AUT and the probe by increasing the measurement distance, but without the need to collect more measurement samples.

This paper provides a comprehensive introduction of an emerging Near-Field (NF) antenna measurement technique using airborne NF-probes installed on Unmanned Aerial Vehicles (UAVs). It sums up the highlights of an ADVANCED Near-Field Antenna Measurement Technology which benefits most the UAV-based measurement approach. An example for the mission requirements will be given with special regard to the airborne segment as used in the new transportable “Hercules” antenna measurement system. The mission requirements will be given based on a planned first measurement campaign characterizing the complete spatial radiation performance of a satellite ground station antenna. The paper will conclude with basic design features of the “Hercules One” airborne platform.

A compact symmetric discone antenna for the 3 GHz to 20 GHz frequency range is demonstrated. The antenna design is optimized for a good transient response with low angular dependency. This property reduces antenna distortions and simplifies antenna de-embedding. The design is based on the well-known biconical antenna, which has been radically enhanced with different geometric features. Far field modal analysis has been used for both the development and the verification of the concept that ensures a constant radiation pattern. A prototype of the balanced antenna with an improved feeding mechanism based on two separate discone antennas together with a three-port balun is also presented. Measurements in the time and in the frequency domain have been performed in order to characterize the antenna. Overall, the results show significantly improved impulse responses and input matching compared to a standard biconical antenna. Therefore, the new antenna is very well suited for advanced channel characterization, reference measurements, and system verifications.

A symmetric compact discone antenna for the 3 GHz to 20 GHz frequency range is presented and characterized. The radiation pattern exhibits excellent frequency independence thanks to a careful theoretical and practical analysis of the radiated spherical modes. The time domain impulse response of the antenna is short and shows very low angular dependence. Moreover, the antenna in equipped with an improved feeding mechanism based on two separate discone antennas. Overall, the results show significantly improved impulse responses and input matching compared to a standard biconical antenna. Hence, the new antenna is well suited for advanced channel characterization, reference measurements, and system verifications.

A theoretical approach is described to determine the equivalent isotropic radiated power (EIRP) of Ultra-Wideband (UWB) impulse radio (IR) transmitters with a very high accuracy. The EIRP is derived from the power spectral density (PSD) of an IR signal model which comprises statistical and physical characteristics. Different components of the transmitter, including the radiation properties of the antennas, are characterized with corresponding impulse responses to increase the precision of the computed EIRP. To verify the theoretical investigations, measurements of exemplary 2-ary modulation schemes have been carried out. A specifically developed software defined radio (SDR) IR transmitter is used to generate arbitrary impulse trains with various modulation schemes and impulse shapes. The resulting EIRP is determined by characterizing the single components of the transmitter with high precision individual measurements or by performing compliance measurements. The theoretical and measured results show very good agreement and hence the presented method is perfectly suited to design IR UWB transceivers.

In this paper a reconfigurable ultra-wideband (UWB) impulse radio (IR) transmitter is presented. The IR signal is synthesized at an intermediate frequency (IF) by employing a multi-Nyquist digital-to-analog converter (DAC) with 12 bit resolution and an update rate of 2.3 GHz. Digital generation of signals in a field programmable gate array (FPGA) guarantees very high flexibility of the reconfigurable design. For upconversion to the radio frequency (RF) band, a first order bandpass (BP) sampling concept and an alternative conventional concept with mixer stages, have been realized. The system enables to generate signals with arbitrary modulation schemes and techniques at an external host personal computer (PC) employing MATLAB. Different measurements using a digitizing oscilloscope have been conducted to demonstrate the performance of the transmitter.

In this paper a pseudo-coherent software-defined impulse-radio (IR) transmitter for the Ultra wideband (UWB) technology is presented. Due to the large available bandwidth, the transmitter is perfectly suited for implementing and testing high precision ranging and positioning systems in dense multi-path indoor environments. Simultaneously, it can offer reliable and secure communication functionalities. A pseudo-coherent transmitter offers the possibility to evaluate the phase information of the carrier frequency in the receiver, in order to improve ranging accuracy or provide additional modulation schemes. The software-defined radio (SDR) solution gives the opportunity to examine arbitrary modulation schemes, communication protocols, impulse shapes or predistortion techniques. The prototype of the transmitter is based on a multi-Nyquist digital to analog converter (DAC) and a field programmable gate array (FPGA) connected to a personal computer (PC) via Universal Serial Bus (USB) interface. Two different approaches for up-conversion to UWB frequency bands are presented and compared to each other.

To investigate impulse radio (IR) communication transceivers, bit error rate (BER) measurements are typically performed by connecting an arbitrary waveform generator and a digitizing oscilloscope. In this paper a reconfigurable software defined radio (SDR) transmitter specifically designed for IR communication tests is presented. The prototype offers the possibility to transmit arbitrary 4-ary modulated impulses with 1 GHz bandwidth over four channels in the frequency range from 6 GHz-10 GHz. For generation of intermediate frequency (IF) signals a subsampling concept with a multi-Nyquist digital to analog converter (DAC) and a field programmable gate array (FPGA) has been employed. Pseudo-coherent signals are synthesized at radio frequency (RF) by utilizing a mixer with a local oscillator (LO) frequency locked to the LO of the DAC. A comparison of theoretically derived signals and measurements shows that both are in close agreement.

I. OVERVIEW Target of the work is the evaluation of the potential of impulse radio (IR) communication systems with respect to commercial usage. Therefore a reconfigurable ultra-wideband (UWB) software defined radio (SDR) transmitter has been developed and the concept is presented in this application note. Besides common SDR concepts the developed IR transceiver employs first order bandpass (BP) sampling at a conversion frequency which is four times the sampling frequency. Hence signals can be directly generated in the radio frequency (RF) band avoiding any non–ideal mixer stages. Furthermore the requirements of the digital signal processing is significantly reduced. The transmitter consists basically of a field programmable gate array (FPGA) and a high speed digital to analog converter (DAC) with 12 bit resolution. This design allows full flexibility and can be adaptively reconfigured in terms of modulation schemes, data rates, and channel equalization. The reconfigurable design will be used for an extensive performance analysis with respect to different modulation schemes, modulation techniques and bitrates required by a various number of applications.