Dielectric Microstrip Research Articles

Two-layer dielectric microstrip line structure: SiO/sub 2/ on Si and GaAs on Si: modeling and measurement

Further development is reported of the modeling of the two-layer dielectric microstrip line structure by computing the scattering parameter S/sub 21/ derived from the model and comparing the computed value with the measured value over the frequency range from 90 MHz to 18 GHz. The sensitivity of the phase of S/sub 21/, and the magnitude of the characteristic impedance to various parameters of the equivalent circuit is also discussed. Examples are given of the measurement and modeling of the SiO/sub 2/ on silicon system to 18 GHz and the modeling of the GaAs on silicon system to 100 GHz. >

Coupling coefficient between dielectric resonator and microstrip line

A new application of the method of electromagnetic field electrical excitation is shown for the purpose of calculation of the dielectric resonator and microstrip line coupling coefficient. Comparison between calculated and measured value of this coefficient shows good agreement.

MIC Overlay Coupler Design Using Spectral Domain Techniques

A quasi-TEM analysis of dielectric overlay microstrip is described for an overlay extending several conductor Iinewidths beyond the coupled lines. This method permits the analysis of numerous variations of overlay coupler geometries. The relevant spectral domain Green's function is given and used to generate a set of design curves when the overlay is identical in thickness and dielectric constant to the main substrate. A trial 8.34-dB coupler was built. Significant improvement in isolation was noted with the overlay when compared to the equivalently designed uncompensated coupler. The measured values of isolation agree very well with predicted values.

Radiation conductance of open-circuit low dielectric constant microstrip

The existing discrepancies between formulas for the radiation conductance of an open-circuit microstrip line are investigated and comparison made with measurements of improved accuracy. It is found that consistent results are obtained if an allowance is made for field-fringing effects in those analyses based on radiation from apertures.

Measurement of Guide Wavelength in Rectangular Dielectric Waveguide

Oscillators in the microwave and millimeter-wave region were constructed wherein the resonators consisted of sections of rectangular dielectric waveguide. While adding thin blocks of dielectric to increase the mechanical length of the resonator, the power output and frequency were measured. Using this technique, the experimental value of the wavelength in the longitudinal direction, lambda/sub g/, was determined. These experimental data were then compared with calculations predicted by optical theory. Good agreement was found where the bulk wavelength was small compared with the cross-sectional dimensions of the dielectric. If the half-wavelength in the dielectric was comparable with the dielectric dimensions, the values of lambda/sub g/ were greater than the theoretical values. In the process of carrying out these experiments, a new type of oscillator is described which provides a power ontput comparable with diodes in metal-walled cavities. In addition, the new dielectric cavities are simple in construction and are compatible with dielectric waveguide, image line, or microstrip systems.

Low Cost Design Techniques for Semiconductor Phase Shifters

The design and performance of two microstrip semiconductor phase shifters operating at S band and UHF are described. The S-band diode phase shifter uses thick-film metallization on a 99.5-percent alumina substrate and uses series coupled diodes for the small bits and constant phase frequency switched life bits for the three large bits. The 4-bit UHF phase shifter uses eight p-i-n diodes mounted in a low dielectric constant microstrip circuit and operates at a power level of 8 kW peak, 240 W average, and has an average insertion loss of 0.7 dB. Phase and VSWR distributions on 800 units produced are also given. The characteristics of two new microwave semiconductor switching devices, the field-effect diode (FED) and the resistive gate switch are described. These devices operate with only a voltage change. Design and performance of an SP2T switch and 3-bit phase shifter using the field-effect diode are presented.

Novel temperature-stable ceramics for microwave dielectric resonators and microstrip substrates

Ceramics comprising homogeneous single-phase zirconate solid solutions of suitable composition have very low temperature coefficients of permittivity, low-frequency permittivities of 30–40 and low losses. Dielectric resonators give Q values up to 4000 and permittivities of 28–35 at 4–5 GHz. The effective permittivity measured on a microstrip ring resonator on a calcium-zirconate substrate shows the dispersion predicted theoretically; the effective permittivity increases from 17 to 23 over the frequency range 1–12 GHz and gives 28.1 as the calculated real value of the permittivity of the substrate. The measured Q value of 200 indicates negligible dielectric losses compared with the I2R losses.