Richard E. Hodges

Design, Analysis, and Development of a Large Ka-Band Slot Array for Digital Beam-Forming Application

This paper discusses the design, analysis, and development of a large Ka-band slot array for digital beam-forming application. The array consists of 160 times 160 elements in 16 subarrays for producing 16 digital beams in the receive mode. Infinite array mutual coupling model has been employed in the design and analysis models. Challenges posed in meeting the pattern and return loss specifications because of manufacturing tolerances are discussed. Measured return loss and pattern characteristics of 10 times 40 slot array modules as well as results on a 1 m times 1 m demonstration array are presented.

Waveguide-Slot Array Antenna Designs for Low-Average-Sidelobe Specifications

This paper discusses the design, analysis, and development of waveguide-fed planar slot arrays to achieve low-average-sidelobe specifications, as may arise in radiometer applications. Such antennas may be required to meet strict average sidelobe levels in different angular regions, and low average return loss over a specified bandwidth. In addition to Elliotts design technique, we used a Moment-Method analysis program, Ansofts HFSS code, and results of tolerance studies using Monte Carlo simulations to meet the design objectives. Comparisons of simulated results and experimental results are also presented.

CubeSat Deployable Ka-Band Mesh Reflector Antenna Development for Earth Science Missions

CubeSats are positioned to play a key role in Earth Science, wherein multiple copies of the same RADAR instrument are launched in desirable formations, allowing for the measurement of atmospheric processes over a short evolutionary timescale. To achieve this goal, such CubeSats require a high-gain antenna (HGA) that fits in a highly constrained volume. This paper presents a novel mesh deployable Ka-band antenna design that folds in a 1.5 U (10 × 10 × 15 cm3) stowage volume suitable for 6 U (10 × 20 × 30 cm3) class CubeSats. Considering all aspects of the deployable mesh reflector antenna including the feed, detailed simulations and measurements show that 42.6-dBi gain and 52% aperture efficiency is achievable at 35.75 GHz. The mechanical deployment mechanism and associated challenges are also described, as they are critical components of a deployable CubeSat antenna. Both solid and mesh prototype antennas have been developed and measurement results show excellent agreement with simulations.

Novel deployable reflectarray antennas for CubeSat communications

Two novel high gain deployable reflectarray antennas to support CubeSat telecommunications are described and compared with other high gain CubeSat antenna technologies. The first reflectarray is the Integrated Solar Array and Reflectarray Antenna (ISARA), a K/Ka-band antenna that also incorporates a dense packing of solar cells used to provide electrical power for the spacecraft. The second is an X-band reflectarray designed to provide a bent pipe telecom link. These reflectarrays are ideal for CubeSat applications because they require negligible stowed volume and impose a modest mass increase. The antenna designs and measured performance results are presented.

The UAVSAR phased array aperture

The development of a microstrip patch antenna array for an L-band repeat-pass interferometric synthetic aperture radar (InSAR) is discussed in this paper. The instrument will be flown on an unmanned aerial vehicle (UAV) and will provide accurate topographic maps for Earth science by 2007. The antenna operates at a center frequency of 1.2575 GHz and with a bandwidth of 80 MHz, consistent with a number of radar instruments that JPL has previously flown. The antenna is designed to radiate orthogonal linear polarizations for fully-polarimetric measurements. Beam-pointing requirements for repeat-pass SAR interferometry necessitate electronic scanning in azimuth over a range of plusmn20degrees in order to compensate for aircraft yaw. Beam-steering is accomplished by transmit/receive (T/R) modules and a beamforming network implemented in a stripline circuit board. This paper focuses on the electromagnetic design of the antenna tiles and associated interconnects. An important aspect of the design of this antenna is that it has an amplitude taper of 10dB in the elevation direction. This is to reduce multipath reflections from the wing that would otherwise be detrimental to interferometric radar measurements. The amplitude taper is provided by coupling networks in the interconnect circuits as opposed to using attenuators in the T/R modules. Details are given of material choices and fabrication techniques that meet the demanding environmental conditions that the antenna must operate in. Predicted array performance is reported in terms of co-polarized and cross-polarized far-field antenna patterns, and also in terms of active reflection coefficient. Measured performance of a 4-element by 2-element antenna tile is presented

Microstrip patch antenna panel for large aperture L-band phased array

This paper describes the design and development of a large, lightweight antenna panel for an active phased array operating at L-band. The panel was developed under a JPL program of technology development for space based radar. It utilizes dual-stacked patch elements that are interconnected with a corporate feed manifold of striplines. This paper focuses on the electromagnetic design and performance of the radiating elements, with emphasis on scan performance, and also addresses mechanical and thermal aspects of the panel. The element in the array environment has a bandwidth of more than 80MHz centered at 1260MHz and is fed so that it can radiate orthogonal linear polarizations. The envisioned phased array, with a nominal aperture of 50m times 2m, is designed to scan plusmn45 degrees in azimuth and plusmn20 degrees in elevation. The panel of radiating elements has a mass density of 3.9 kg/m2, which represents approximately 50% of the target 8kg/m2 total panel mass density that includes T/R modules and feed manifolds

Slot array antennas for the Juno radiometer application

In this paper, the design and analysis of two planar array geometries, the conventional one and a symmetric design that exhibits significantly lower sidelobe levels is discussed.

CubeSat deployable Ka-band reflector antenna for Deep Space missions

While CubeSats have thus far been used exclusively in Low Earth Orbit (LEO), NASA is now investigating the possibility to deploy CubeSats beyond LEO to carry out scientific experiments in Deep Space. Such CubeSats require a high-gain antenna that fits in a constrained and limited volume. This paper introduces a 42.8 dBi gain deployable Ka-band antenna folding in a 1.5U stowage volume suitable for 3U and 6U class CubeSats.

A G-Band 160 GHz T/R Module Concept for Planetary Landing Radar

In this work, the concept of a G-band transmit/receive (T/R) module centered at 160 GHz was discussed. The design makes use of state-of-the-art G-band MMIC low noise amplifiers and power amplifiers, and a high speed SPDT InGaAs PIN diode switch. The paper reports on the designs, chip results, and the integration concept for a 160 GHz T/R module. The G-band T/R module has applications toward precision altimetry and velocimetry measurements in landing radar, such as in future planetary landers on the surface of Mars

The use of waveguide simulators to measure the resonant frequency of Ku-band microstrip arrays

This paper describes the use of waveguide simulators for measuring the reflection coefficient of infinite arrays of free-standing microstrip elements illuminated by a plane wave. Waveguide simulators have long been used to measure the active impedance of phased array elements in a mutual coupling environment. We have extended the technique in order to measure the resonant frequency of arrays of free-standing microstrip elements. Using these measurements along with validated MoM codes, we are able to indirectly determine the dielectric constant of our antenna substrate material.