Search NASA⌕ Search

SEARCH · Search NASA

Results for “insertion loss”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Correlation of Electric Field and Critical Design Parameters for Ferroelectric Tunable Microwave Filters

The correlation of electric field and critical design parameters such as the insertion loss, frequency ability return loss, and bandwidth of conductor/ferroelectric/dielectric microstrip tunable K-band microwave filters is discussed in this work. This work is based primarily on barium strontium titanate (BSTO) ferroelectric thin film based tunable microstrip filters for room temperature applications. Two new parameters which we believe will simplify the evaluation of ferroelectric thin films for tunable microwave filters, are defined. The first of these, called the sensitivity parameter, is defined as the incremental change in center frequency with incremental change in maximum applied electric field (EPEAK) in the filter. The other, the loss parameter, is defined as the incremental or decremental change in insertion loss of the filter with incremental change in maximum applied electric field. At room temperature, the Au/BSTO/LAO microstrip filters exhibited a sensitivity parameter value between 15 and 5 MHz/cm/kV. The loss parameter varied for different bias configurations used for electrically tuning the filter. The loss parameter varied from 0.05 to 0.01 dB/cm/kV at room temperature.

Subramanyam, Guru↗
NASA NTRS1983

30/20 GHz spacecraft GaAs FET solid state transmitter for trunking and customer-premise-service application

Sixteen 30 dB 0.5 W amplifier modules were combined to satisfy the requirement for a graceful degradation. If one module fails, the output power drops by only 0.43 dB. Also, by incorporating all the gain stages within the combiner the overall combining efficiency is maximized. A 16 way waveguide divider combiner was developed to minimize the insertion loss associated with such a large corporate feed structure. Tests showed that the 16 way insertion loss was less than 0.5 dB. To minimize loss, a direct transition from waveguide to microstrip, using a finline on duroid substrate, was developed. The FETs fabricated on MBE grown material, demonstrated superior performances. For example, a 600 micrometer device was capable of 320 mW output power with 5 dB gain and 26.6% efficiency at 21 GHz. The 16 module amplifier gave 8.95 W saturated output power with 30 dB gain. The overall efficiency was 9%. The 3 dB bandwidth was 2.5 GHz. At 17.7 GHz the amplifier had 5 W output power and at 20.2 GHz it still had 4.4 W.

Saunier, P.↗
NASA NTRS1984

Experimental study of noise transmission into a general aviation aircraft

The effect of add-on treatments on noise transmission into a cabin of a light aircraft was studied under laboratory conditions for diffuse and localized noise inputs. Results indicate that stiffening skin panels with honeycomb would provide on the average 3dB to 7 dB insertion loss over the most of selected frequency range H1 to 1000 Hz. Addition of damping tape on top of the honeycomb treatment increases insertion loss by 2dB to 3dB. Porous acoustic blankets show no attenuation of transmitted noise for frequencies below 300 Hz. Insertion of impervious vinyl septa between the layers of porous acoustic blankets do not provide additional noise reduction for frequencies up to about 500 Hz. Similar behavior was observed for noise barriers composed of urethane elastomer, decoupler foam and acoustic foam. A treatment composed from several layers of acoustic foams does not increase noise attenuation for the entire frequency range studied. An acoustic treatment composed of honeycomb panels, constrained layer damping tape, 2 to 3 inches of porous acoustic blankets, and limptrim which is isolated from the vibrations of the main fuselage structure seems to provide the best option for noise control.

Vaicaitis, R.↗
NASA NTRS1984

Superconducting Nbti and Pb(cu) Bandpass Filters

Superconducting Nb0.45Ti0.55 and Pb electroplated on Cu bandpass microwave filtes were constructed to investigate their low loss properties at 4.7 K. An interdigital stripline filter configuration was selected as the optimum structure for future applications. The filter was designed to operate at 8.45 GHz with an equal ripple bandwidth of 0.15 GHz. The insertion loss and the noise temperature contribution were measured at 4.7 K. In addition, the insertion loss was studied as a function of out of band power (up to 1 watt) and temperature (4.7 K up to T(c)). Results of an oxygen free high conductivity Cu filter are included for comparison.

Bautista, J. J.↗
NASA NTRS1985

Superconducting NbTi and Pb(Cu) bandpass filters

Superconducting NbO.45Ti0.55 and Pb electroplated on Cu bandpass microwave filters were constructed to investigate their low loss properties at 4.7 K. An interdigital stripline filter configuration was selected as the optimum structure for future applications. The filter was designed to operate at 8.45 GHz with an equal ripple bandwidth of 0.15 GHz. The insertion loss and the noise temperature contribution were measured at 4.7 K. In addition, the insertion loss was studied as a function of out of band power (up to 1 watt) and temperature (4.7 K up to Tc). Results of an oxygen free high conductivity Cu filter are included for comparison.

Bautista, J. J.↗
NASA NTRS1983

A Ka-band GaAs monolithic phase shifter

The design and performance of a GaAs monolithic 180-degree one-bit switched line phase shifter test circuit for Ka-band operation is presented. A self-aligned gate (SAG) fabrication technique is also described that reduces resistive parasitics in the switching FET's. Over the 27.5-30 GHz band, typical measured differential insertion phase is within 10-20 deg of the ideal time delay characteristic. Over the same band, the insertion loss for the SAG phase shifter is about 2.5-3 dB per bit. The SAG fabrication technique holds promise in reducing phase shifter insertion loss to about 1.5 dB/bit for 30-GHz operation.

Sokolov, V.↗
NASA NTRS1991

Applications of a high power four-way power divider and combiner and a cross-over circuit

Circuits of rectangular waveguides coupled to a cylindrical cavity have been studied. Two types of circuits were developed: a high-power four-way power divider/combiner with less than 0.5 dB insertion loss over a 20 percent bandwidth and a high-power four-port cross-over circuit with less than 0.7 dB insertion loss and 20 dB isolation at X-band. To demonstrate the feasibility of the first circuit, a power combiner was built by connecting four Gunn oscillators to the four rectangular waveguide ports of the radial waveguide. A power combining efficiency of over 70 percent was achieved at X-band. The second circuit was used to feed a dual-polarization cross-slot antenna backed by a cylindrical cavity.

Chang, Kai↗
NASA NTRS1991

Performance of a high Tc superconducting ultralow-loss microwave stripline filter

The successful fabrication is reported of a five-pole interdigital stripline filter made of the 93 K superconductor Y1Ba2Cu3O(y) coated on a silver substrate, with a center frequency of 8.5 GHz and an extremely high rejection ratio of 80 dB. The lowest insertion loss measured was 0.1 dB at 12 K, with a return loss better than 16 dB, representing significant improvements over a similar Cu filter, and comparable to low Tc filters. The insertion loss appears to be limited by extrinsic factors such as tuning mismatch and joint losses, and not by the superconducting material losses.

Zahopoulos, C.↗
NASA NTRS2010

Nanoionics-Based Switches for Radio-Frequency Applications

Nanoionics-based devices have shown promise as alternatives to microelectromechanical systems (MEMS) and semiconductor diode devices for switching radio-frequency (RF) signals in diverse systems. Examples of systems that utilize RF switches include phase shifters for electronically steerable phased-array antennas, multiplexers, cellular telephones and other radio transceivers, and other portable electronic devices. Semiconductor diode switches can operate at low potentials (about 1 to 3 V) and high speeds (switching times of the order of nanoseconds) but are characterized by significant insertion loss, high DC power consumption, low isolation, and generation of third-order harmonics and intermodulation distortion (IMD). MEMS-based switches feature low insertion loss (of the order of 0.2 dB), low DC power consumption (picowatts), high isolation (>30 dB), and low IMD, but contain moving parts, are not highly reliable, and must be operated at high actuation potentials (20 to 60 V) generated and applied by use of complex circuitry. In addition, fabrication of MEMS is complex, involving many processing steps. Nanoionics-based switches offer the superior RF performance and low power consumption of MEMS switches, without need for the high potentials and complex circuitry necessary for operation of MEMS switches. At the same time, nanoionics-based switches offer the high switching speed of semiconductor devices. Also, like semiconductor devices, nanoionics-based switches can be fabricated relatively inexpensively by use of conventional integrated-circuit fabrication techniques. More over, nanoionics-based switches have simple planar structures that can easily be integrated into RF power-distribution circuits.

Nessel, James↗
NASA NTRS1991

Performance of a high T(sub c) superconducting ultra-low loss microwave stripline filter

Discussed here is the successful fabrication of a five-pole interdigital stripline filter made of the 93-K superconductor (Y1Ba2Cu3O(y)) coated on a silver substrate, with center frequency of 8.5 GHz and an extremely high rejection ratio of 80 dB. The lowest insertion loss measured was 0.1 dB at 12 K, with a return loss of better than 16 dB, representing a significant improvement over a similar copper filter; it is comparable to low critical temperature filters. The insertion loss appears to be limited by extrinsic factors, such as tuning mismatch and joint losses, and not by the superconducting material losses.

Bautista, J. J.↗
NASA NTRS1988

Dual passband dichroic plate for X-band

A need arose in the Deep Space Network for a dichroic plate that would simultaneously pass two desired frequency bands in the X-band region. In addition, the plate must be totally reflective for S-band frequencies. A dielectrically loaded dichroic plate is described that was developed to meet this need. The unique microwave properties that the new dichroic plate had to possess were: (1) insertion losses of less than 0.04 dB for X-band uplink frequencies centered at 7167 MHz and for X-band downlink frequencies centered at about 8425 MHz; (2) insertion losses that met the low loss requirements at 30 deg incidence angle simultaneously for both parallel and perpendicular polarizations; (3) total reflectivity at S-band frequencies; and (4) ability to maintain these electrical characteristics while passing 100 kW of CW power at X-band or while reflecting 100 kW of CW power at S-band. The dual passband dichroic plate is a thick metallic plate having an array of periodic round holes filled with Teflon plugs. Test results on an experimental prototype plate indicate that it is technically possible to design a dielectrically filled dichroic plate that meets all of the technical requirements.

Otoshi, T. Y.↗
NASA NTRS2000

Sound Absorption of a 2DOF Resonant Liner with Negative Bias Flow

This report describes an experimental study conducted to determine the effect of negative bias flow on the sound absorption of a two degree-of-freedom liner. The backwall for the liner was designed to act as a double-Helmholtz resonator so as to act as a hard wall at all frequencies except at its resonant frequencies. All normal incident impedance data presented herein was acquired in an impedance tube. The effect of bias flow is investigated for a buried septum porosity of 2% and 19.5% for bias flow orifice mach numbers up to 03 11. As a porous backwall is needed for the flow to pass through, the effect of bias flow on this backwall all had to be evaluated first. The bias flow appears to modify the resistance and reactance of the backwall alone at lower frequencies up to about 2 kHz, with marginal effects at higher frequencies. Absorption coefficients close to unity are achieved for a frequency range of 500-4000 Hz for the overall liner for a septum porosity of 2% and orifice mach number of 0.128. Insertion loss tests performed in a flow duct facility for grazing flow Mach numbers up to 0.2 and septum mach numbers up to 0.15 showed that negative bias flow can increase insertion loss by as much as 10 dB at frequencies in the range of 500 - 1400 Hz compared to no grazing flow. The effectiveness of the negative bias flow is diminished as the grazing flow velocity is increased.

Ahuja, K. K.↗
NASA NTRS2000

Sound Absorption of a 2DOF Resonant Liner with Negative Bias Flow

This report describes an experimental study conducted to determine the effect of negative bias flow on the sound absorption of a two degree-of-freedom liner. The backwall for the liner was designed to act as a double-Helmholtz resonator so as to act as a hard wall at all frequencies except at its resonant frequencies. The effect of bias flow is investigated for a buried septum porosity of 2% and 19.5% for bias flow orifice Mach numbers up to 0.311. The bias flow appears to modify the resistance and reactance of the backwall alone at lower frequencies up to about 2 kHz, with marginal effects at higher frequencies. Absorption coefficients close to unity are achieved for a frequency range of 500 - 4000 Hz for the overall liner for a septum porosity of 2% and orifice Mach number of 0.128. Insertion loss tests performed in a flow duct facility for grazing flow Mach numbers up to 0.2 and septum Mach numbers up to 0.15 showed that negative bias flow can increase insertion loss by as much as 10 dB at frequencies in the range of 500 D 1400 Hz compared to no grazing flow. The effectiveness of the negative bias flow is diminished as the grazing flow velocity is increased.

Ahuja, K. K.↗
NASA NTRS1982

Evaluation of waveguide coating materials

Waveguide coating materials were tested at 8470 MHz for insertion loss. Samples of these coatings on waveguide pieces without flanges were tested in an environmental chamber to simulate the effects of high power microwave heating. Test results indicated that three types of coating materials are acceptable with regard to insertion loss. However, simulated microwave heating caused debonding of Metcot 7 and BD-991 coatings, resulting in peelings in the waveguide. The higher cost Chemglaze R104 does not exhibit this problem.

Chen, W. C. J.↗
NASA NTRS1999

Thin Film Ba(x)Sr(1-x)TiO3 Ku- and K-Band Phase Shifters Grown on MgO Substrates

We report measurements of gold circuits fabricated on four Ba(x)Sr(1-x)TiO3 films doped with 1% Mn grown on MgO substrates by laser ablation. Low frequency measurements of epsilon(sub r) and tan(delta) on interdigital capacitors are compared with high frequency measurements of phase shift and insertion loss on coupled microstrip phase shifters done on the same films. The variation in temperature of both high and low frequency device parameters is compared. Annealed and unannealed films are compared. Room temperature figures of merit of phase shift per insertion loss of up to 58.4 C/dB at 18 GHz and 400 V dc bias were measured.

VanKeuls, F. W.↗
NASA NTRS2000

Finite Ground Coplanar Waveguide Shunt MEMS Switches for Switched Line Phase Shifters

Switches with low insertion loss and high isolation are required for switched line phase shifters and the transmit/receive switch at the front end of communication systems. A Finite Ground Coplanar (FGC) waveguide capacitive, shunt MEMS switch has been implemented on high resistivity Si. The switch has demonstrated an insertion loss of less than 0.3 dB and a return loss greater than 15 dB from 10 to 20, GHz. The switch design, fabrication, and characteristics are presented.

Ponchak, George E.↗
NASA NTRS2000

Analysis and Optimization of Thin Film Ferroelectric Phase Shifters

Microwave phase shifters have been fabricated from (YBa2Cu3O(7-delta) or Au)/SrTiO3 and Au/Ba(x)Sr(1-x)TiO3 films on LaAlO3 and MgO substrates. These coupled microstrip devices rival the performance of their semiconductor counter-parts parts at Ku- and K-band frequencies. Typical insertion loss for room temperature ferroelectric phase shifters at K-band is approximately equal 5 dB. An experimental and theoretical investigation of these novel devices explains the role of the ferroelectric film in overall device performance. A roadmap to the development of a 3 dB insertion loss phase shifter that would enable a new type of phased array antenna is discussed.

Romanofsky, Robert R.↗