We present the development of a Ku-band (10-16 GHz) corrugated conical horn antenna using 3-D print technology or stereolithography. The antenna is printed using acrylonitrile butadiene styrene (ABS), a thermoplastic, and then coated with conductive aerosol paint. The designed antenna achieves a measured peak gain of 19.6 dBi at 16 GHz with a 1.92:1 VSWR from 11 to 18 GHz. It is shown that 3-D printing is capable of producing sufficient feature sizes that make operation in the microwave/millimeter-wave (MMW) bands possible.

Development of a Ku-Band Corrugated Conical Horn Using 3-D Print Technology

Additive manufacturing technologies are currently envisaged to boost the development of a next generation of microwave and millimeter-wave devices intended for, among others, satellite telecommunications, navigation, imaging, radio-astronomy, and cosmology. Due to their excellent electromagnetic and mechanical properties, all-metal waveguide components are key building blocks of several radio frequency (RF) systems used in these application domains. This article reports on the prospects originating from the application of all-metal 3D printing to the manufacturing of high-performance microwave waveguide devices. The technology investigated is the selective laser melting process, where a laser beam is used to fuse metal powder particles spread over a building platform. The complete parts are built by overlapping several constant-thickness layers. An overview on process parameters, material properties, and design rules is reported for this technology. The electromagnetic properties of test samples built in Al and Ti alloys have been experimentally characterized. A robust design of Ku/K-band filters aimed at satellite telecommunications has been implemented in several prototypes manufactured in Al. The corresponding measured performance confirm the applicability of the laser selective melting process to the intended applications.

Selective Laser Melting Manufacturing of Microwave Waveguide Devices

Radio-frequency (RF) electronics, which combine passive electromagnetic devices and active transistors to generate and process gigahertz (GHz) signals, provide a critical basis of ever-pervasive wireless networks. While transistors are best realized by top-down fabrication, relatively larger electromagnetic passives are within the reach of printing techniques. Here, direct writing of viscoelastic silver-nanoparticle inks is used to produce a broad array of RF passives operating up to 45 GHz. These include lumped devices such as inductors and capacitors, and wave-based devices such as transmission lines, their resonant networks, and antennas. Moreover, to demonstrate the utility of these printed RF passive structures in active RF electronic circuits, they are combined with discrete transistors to fabricate GHz self-sustained oscillators and synchronized oscillator arrays that provide RF references, and wireless transmitters clocked by the oscillators. This work demonstrates the synergy of direct ink writing and RF electronics for wireless applications.

Gigahertz Electromagnetic Structures via Direct Ink Writing for Radio-Frequency Oscillator and Transmitter Applications.

Tandem-L is proposed as a spaceborne synthetic aperture radar (SAR) mission developed and operated by the German Aerospace Center in cooperation with several Helmholtz research centers and the German space industries. The mission concept comprises two fully polarimetric radar satellites providing monostatic and bistatic SAR imagery. A key feature of these SAR sensors is the employment of large lightweight unfurlable mesh reflectors fed by digital feed arrays. The main advantage of this new SAR system concept is the provision of large antenna apertures in space and flexible operation via reconfigurable feed electronics. By this, it becomes possible to map, for the first time, a continuous 350-km wide swath with a 7-m azimuth resolution with excellent noise equivalent sigma zero and ambiguity suppression. This paper shall give an overview on the technical aspects of the Tandem-L SAR instrument and antenna design. In particular, after a short review of the SAR system requirements, the concept of reflector SAR systems is outlined and the operation principle is presented. General guidelines for the design of array-fed reflector antennas with application to SAR imaging are given. Then, the optimization approach of the feed array design is detailed with a specific emphasis on a fixed beamforming concept in azimuth. In this context, also the problem of cross-pol pattern mitigation is addressed. These optimization steps are shown to be crucial for achieving the performance requirements in quad-pol acquisitions. Beamforming in elevation is performed onboard the spacecraft via digital hardware. This paper presents the beamforming architecture on receive for Tandem-L, which would apply in general for instance also to planar multielevation beam SAR antennas with Scan-On-Receive capabilities. Tandem-L is operated as a staggered SAR, which means varying the pulse repetition interval from pulse to pulse. In this context, the major design challenges are presented. Moreover, the impact of pulse staggering on the imaging performance is discussed. Tandem-L’s SAR performance is presented by means of numerical simulations showing that the performance requirements imposed by the scientific user community could be met. The final part of this paper addresses options for high azimuth resolution imaging as well as a beamforming method for enhanced range ambiguity suppression.

/pdf/tandem-l-a-technical-perspective-on-future-spaceborne-sar-1ksnrb2ntn.pdf

Tandem-L: A Technical Perspective on Future Spaceborne SAR Sensors for Earth Observation

Presents the concept of additive manufacturing and examines the implications for next generation microwave and millimeter wave systems.

Additive manufacturing: a key enabling technology for next-generation microwave and millimeter-wave systems [point of view]

A new $E$ -plane filtering structure suitable for very high-power telecom satellite applications is presented. The conceived configuration exploits the design flexibility provided by cascading highly integrated step/stub resonators with pseudoelliptic frequency responses. Several design examples of filters and diplexers in Ku-, K-, and Q-band are reported and supported by experimental tests campaigns. The components have been designed with a full-wave 2-D spectral element method. Prototypes have been realized in aluminum clam-shell technology. Excellent agreement between the models and the experimental results has been achieved. An alternative manufacturing of the proposed architecture based on the selective laser melting technology is also reported. The attractiveness of the structure in view of this emerging additive manufacturing solution is demonstrated. The main advantages of the proposed filter configuration suitable for components operated in heavily loaded multi-carrier environment are: compact design, very low losses, high rejection, and high power-handling capability.

Enhanced Topology of $E$ -Plane Resonators for High-Power Satellite Applications

Three different RF chain architectures operating in the FSS (Fixed Satellite Services) + BSS (Broadcast Satellite) spectrum are presented and discussed. The RF chains are based on a common wideband corrugated feed horn, but differ on the approach used for bands and polarizations separation. A breadboard of a novel self-diplexed configuration has been designed, manufactured and tested. It proves to be the preferred candidate for bandwidth, losses and power handling. Very good correlation of the RF performance to the theoretical design is found.

https://ieeexplore.ieee.org/iel5/4977244/5067558/05068258.pdf

Wideband diplexed feed chains for FSS + BSS applications

This paper deals with feed array suitable to SAR mission employing large reflector antennas (∼10–15m projected diameter). The feed array, in patch technology, is specifically designed to accomplish various mission operative modes in a modular way. A key feature of such feedarray is the capability of cancelling the high cross-polar components at secondary level, intrinsically generated by large reflector with short F/D ratio, allowing the SAR instrument operating in dual linear polarization.

P-band feedarray for BIOMASS

Array-fed unfurlable reflector antennas in the 12m class can be can be a viable alternative to large direct radiating arrays, for low frequency SAR applications. In this paper several architectural solutions for a P-band (435 MHz) SAR antenna relying on the current technology of a 12m EQM reflector developed within a previous ESA program [1], are described. The proposed illumination system is based on a patch array where a doublet in stripline technology is employed as building brick. It has the capability to cancel the high cross-polar level generated by the offset reflector geometry at reduced F/D (∼0.5), through a suitable simple integrated network. This feature is of primarily importance to the dual linear polarization SAR functionality in full polarimetry imaging. The complete feedarray ranges from two to four such doublets allowing providing a lot of flexibility in SAR operative modes.

Unfurlable reflector SAR antenna at P-band

Scope of this work is to highlight the heritage dev eloped by ThalesAleniaSpace-Italia (TASI) in HF deployable dipoles for Radar Sounders applications. The RF experience acquired by TAS-I in the frame of the SHARAD P/L (SHAllow RADar PayLoad) provided by the Italian Space Agency (ASI) as a facility instrument for the 2005 NASA mission to Mars called MRO (Mars Reconnaissance Orbiter) was complemented within the ESA study named HILDRA (Highly Integrated Low power ice penetrating Deployable Radar Antenna), by exploiting the technology relevant to the deployable dipole. This ESA study entails the design and the development and verification of a technology demonstrator for a highly integrated low power ice penetrating Radar Antenna, targeting the next European and US deep space missions within Horizon 2020 program. The paper summarises the technological development activity experienced by TAS-I including trade-off and design capabilities both at system and at unit level for electrical and technology aspects, includ ing the test campaign carried out over the demonstrator. Main objective of the Demonstration Model (DM) was to exhibit by test the deployment performance of the selected technology, as the deployment of the long dipole was recognised a critical issue for the feasibility of the JUICE (JUpiter ICy Moon Explorer) mission.

R. Mizzoni

Papers

Enhanced Topology of $E$ -Plane Resonators for High-Power Satellite Applications

Wideband diplexed feed chains for FSS + BSS applications

P-band feedarray for BIOMASS

Unfurlable reflector SAR antenna at P-band

Development of long deployable dipole antennas for Sounder Radars in ThalesAleniaSpace-Italia