Lightweight, Self-Deployable Helical Antenna

NASA's patch antenna technology exhibits higher operational bandwidth (on the order of 20%) than typical patch antennas (less than 10%) and can operate across integer-multiple frequency bands (e.g. S/X, C/X, S/C). Testing of the antenna design has demonstrated &#62 6dB of gain on both S and X bands (boresight), with an axial ratio of &#60 6dB and voltage standing wave ratio (VSWR) &#60 3:1 throughout the entire near-Earth network (NEN) operating bands (22.4GHz and 88.4GHz) with hemispherical coverage. The patch size is on the order of 10 x 10 cm and with associated electronics, is about 1 cm in height.

SmallSat Standardized Architecture is architecture that is modularized, pressurizable, thermally controlled spacecraft-designed to host ruggedized commercial off-the-shelf (COTS) instrumentation in a terrestrial-like environment on orbit. The architecture takes advantage of a pressurizable volume for both spacecraft and payload systems. The pressurizable volume provides multiple benefits, primarily in thermal design. By maintaining one atmosphere of pressure inside the SmallSat, materials that might otherwise outgas and/or fail and/or cause significant contamination issues, are no longer a concern. This also means that certain vibration-absorbing materials/designs used in COTS hardware can be used on orbit. Additionally, printed circuit boards do not have to be redesigned for thermal requirements, plus conformal coating and contamination bake-outs are no longer required. The SmallSat architecture is designed to take advantage of the United States Air Force (USAF) Rideshare Program and the Evolved Expendable Launch Vehicle Secondary Payload Adaptor (ESPA) ring. The ESPA ring comes in two sizes: standard and Grande. The architecture has two main configurations, one designed for the ESPA Grande, and the other for the standard ESPA ring. The ESPA Grande version is a hockey-puck-shaped spacecraft bus measuring approximately 40 inches in diameter and 20 inches in height. This version takes full advantage of the ESPA Grande’s 300-kilogram capability per attachment point.

The HDRSC hardware implementation employs the latest cutting edge silicon technologies to calculate the time delay between signals of spatially disparate antennas. After first converting the incoming signals to the digital domain, the unit determines the time difference between the antenna arrivals. Knowing the time delay to within utmost accuracy, the unit while still in the digital domain adds the signals. The resulting coherently combined signal is then converted back to the analog domain. Updates to the time difference estimates are accomplished on the order of milliseconds so the whole process can be completed in real time during a spacecraft pass.

JPL's patch antenna comprises a conductive patch attached to a ground plane by a support post and a probe connector arranged to conduct electromagnetic energy to the conductive patch (for signal transmission) or from the conductive patch (for signal reception). The central support post improves the mechanical stability of the antenna and increases its bandwidth without significantly affecting its radiation pattern performance. The conductive patch can include ribs that extend from the center axis to the outer edges of the patch to stabilize it further. An all-metal patch antenna has been fabricated and subjected to thermal and vibration testing. The antenna was thermally cycled three times from 135 °C to 120 °C; no damage to either the support post or the antenna was observed. In addition, the return loss was very close to pretest measurements, indicating essentially no hysteresis. The antenna was vibration tested using 40 g z-axis and 20 g x- and y-axis; the vibration frequency shifts were less than 5%, and no structural failures or signs of probe abrasion were observed.

The patch antenna consists of two radiating metal patch elements, a metal feed circuit, choke rings, several alignment spacers, a SMA connector, and a mounting lid giving the antenna a total diameter of 54 mm; small enough to fit in a coffee cup. The signal is carried between the lower patch and the circuit via a coaxial transmission structure, in which the probes are the inner conductor and the antenna structure is the outer conductor. The patch antenna is constructed entirely of metal, offering rugged physical durability while delivering superior performance. This advanced material not only enables the antenna to handle higher power loads (exceeding 10 watts) but also ensures exceptional stability under demanding conditions—outperforming standard patch antennas made with traditional dielectric materials. It is also not susceptible to the manufacturing variability incurred from using dielectrics. Ideally, this metallic design also allows for reentry and reuse across missions. The patch antenna is designed with integrated choke rings to effectively mitigate multipath signal interference, delivering an impressive front-to-back ratio of over 35 dB. Its integrated polarizer circuit enhances signal clarity and boosts overall efficiency, ensuring reliable communication in challenging environments. With support for both right- and left-handed circular polarization, the antenna achieves a co-polarization peak gain of 9 dBi and an axial ratio of less than 3 dB within a wide 50-degree orientation range. These advanced features provide superior signal performance and consistent clarity across diverse applications. Although designed for space and planetary exploration applications, the antenna may also be valuable for terrestrial use cases with rugged conditions. The X-band patch antenna is at technology readiness level (TRL) 5 (component and/or breadboard validation in relevant environment) and is available for patent licensing.