Bandpass Structure Research Articles

Optimized RC-NIC bandpass structures

The optimized structure presented by Prasad and Khanijo is compared with an earlier realization due to Huelsman. It is seen that a suitable choice of numerator constant can both reduce the number of elements and improve the network sensitivity to variations in NIC conversion ratio.

Synchronously tuned ferrite power limiter for broad-band systems application

This investigation describes analytical and experimental results obtained on a broadband ferrite limiter at K <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</inf> band which utilizes a synchronously tuned waveguide bandpass structure. This device is aimed at providing protection for communications and electronic warfare systems over a bandwidth from 12 to 30 percent at K <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</inf> -band frequencies. The circuit consists of a series of three cavities in a waveguide transmission line, the coupling being accomplished via the irises or symmetrical inductive slits between cavities. Because of this cavity structure, the observed threshold power levels have been reduced by an order of magnitude. By utilizing a combination of single crystal YIG and lithium ferrite rods, the threshold power for limiting varies from 0.75 W at 16.0 GHz to 2.0 W at 17.0 GHz with an insertion loss of 0.9 dB.

Sinusoidal oscillations in band-pass filters†

An oscillatory system comprising an active RC band-pass filter, an amplifier with negative gain and a clipper is described. It has been observed that by suitable selection of the band-pass structure and appropriate gain adjustments' a sine wave oscillation of wide frequency range can be obtained. Expressions for frequency and amplitude are derived and verified by experimental studies.

Bandpass and Pseudo-High-Pass Quasi-Optical Filters

Two forms of quasi-optical filters are discussed herein for use at millimeter-wave frequencies and possibly for far infrared frequencies. One form consists of metallic grids with intervening dielectric support material which forms a quasi-optical filter analogous to the inductively coupled waveguide bandpass filter. Because of dielectric losses, the relatively weak upper stopband, and the rapidly repeating passbands, this type of structure leaves much to be desired as a bandpass quasi-optical filter. However, when designed for wide bandwidth, it makes a very good pseudo-high-pass filter. For moderate- to wide-band bandpass applications, pseudo-high-pass filters of this type can be designed to match with a form of quasi-optical low-pass filter previously treated by the authors, in order to give a bandpass filter with strong, broad stopbands on both sides of the passband. Design principles, computed performance, and experimental results are presented for both pseudo-high-pass and bandpass structures.

Comments on "High-Q Resistance Capacitance Ladder Phase-Shift Networks" and "High-Q Bandpass and Band-Elimination Resistance-Capacitance Ladder Structures

Comments on "High-Q Resistance Capacitance Ladder Phase-Shift Networks" and "High-Q Bandpass and Band-Elimination Resistance-Capacitance Ladder Structures

Author's reply to Comments on 'High-Q Resistance Capacitance Ladder Phase-Shift Networks' and 'High-Q Bandpass and Band-Elimination Resistance-Capacitance Ladder Structures'

Author's reply to Comments on 'High-Q Resistance Capacitance Ladder Phase-Shift Networks' and 'High-Q Bandpass and Band-Elimination Resistance-Capacitance Ladder Structures'

High-Q Bandpass and Band-Elimination Resistance-Capacitance Ladder Structures

In a previous paper,[1] the properties of high- Q resistance-capacitance (R-C) ladder structures having lowpass and highpass configurations were discussed. In this correspondence, bandpass and band-elimination structures are considered. These R-C structures are also expected to fulfill the following two conditions: 1) the factor Q = \omega_{0}/2{\cdot}d {\phi}/dw|_{\omega = \omega \c} ,(where \phi is the phase shift between the input and the output, and \omega_0 is the frequency at which \phi = 180°) shall be a maximum possible; and 2) the open-circuit input impedance and the short-circuit output admittance shall be simultaneously maximized.

A Design Technique for Realizing a Microwave Tunnel-Diode Amplifier in Stripline

A significant problem in realizing a practical tunnel-diode amplifier is that of stabilizing the amplifier both within and outside its passband while maintaining a specified center-frequency gain and bandwidth. A new technique for realizing a moderate-bandwidth tunnel-diode amplifier that utilizes a directional filter as a bandpass structure is described. This technique was investigated analytically and an experimental S-band amplifier was built and tested. This experimental amplifier had typically the following characteristics: bandwidth, 400 MHz; center frequency, 2.9 GHz; and center-frequency gain, 12.5 dB. The technique described yields an amplitler which is reproducible and which has an analytically predictable and well-defined response. None of the experimental models have shown any tendencies toward oscillation.

Relation between amplification and bandwidth of parametric travelling-wave amplifiers using varactor diodes

The paper discusses parametric travelling-wave amplifiers whose wave-guide has the character of a band-pass filter. For two band-pass structures of practical importance which contain as lumped capacitances merely the basic capacitances of varactor diodes, the maximum product is estimated of the gain per diode at the mid-band frequency by the relative bandwidth that can be attained with parametric travelling-wave amplification. It is assumed that the mid-band frequency of the amplifying action equals half the pump frequency, that it is at the centre of the pass-band of the band-pass guide, and that the bandwidth of the amplifying action agrees with the bandwidth of the band-pass guide. It is further assumed that the amplitude of the controlled diode capacitance variation is 50% of the basic diode capacitance. A maximum of about 2 dB per diode results for the aforementioned product which we term “effectiveness”. Unlike the bandwidth-gain product of conventional amplifiers, it is thus for the here discussed parametric travelling-wave amplifiers no longer the absolute, but the relative bandwidth which is representative. Effectiveness values of about 0·5 to 1·4 dB per diode can be gathered from existing experimental results of the author and others.