This paper presents a novel photonic bandgap (PBG) structure for microwave integrated circuits. This new PBG structure is a two-dimensional square lattice with each element consisting of a metal pad and four connecting branches. Experimental results of a microstrip on a substrate with the PEG ground plane displays a broad stopband, as predicted by finite-difference time-domain simulations. Due to the slow-wave effect generated by this unique structure, the period of the PBG lattice is only 0.1/spl lambda//sub 0/ at the cutoff frequency, resulting in the most compact PEG lattice ever achieved. In the passband, the measured slow-wave factor (/spl beta//k/sub 0/) is 1.2-2.4 times higher and insertion loss is at the same level compared to a conventional 50-/spl Omega/ line. This uniplanar compact PBG (UC-PBG) structure can be built using standard planar fabrication techniques without any modification. Several application examples have also been demonstrated, including a nonleaky conductor-backed coplanar waveguide and a compact spurious-free bandpass filter. This UC-PBG structure should find wide applications for high-performance and compact circuit components in microwave and millimeter-wave integrated circuits.

A uniplanar compact photonic-bandgap (UC-PBG) structure and its applications for microwave circuit

This paper provide a review of the active integrated antenna (AIA) technologies. After a brief introduction on the definition and some historical remarks, the paper concentrates on the research effort on the past decades or so. The AlAs are reviewed in its various functions. First, an oscillator-type AIA is presented, followed by very interesting aspects of coupled oscillator arrays for phase control. Use of an AIA concept for efficient RF front ends is described with examples on high-power amplifier AlAs. Next, a phase-conjugation-based retrodirective array is reviewed. Finally, AIA systems for receiving, transmitting, and duplexing are reviewed.

Active integrated antennas

Ground planes of conductor-backed coplanar waveguides (CBCPWs) behave like overmoded patch antennas supporting parallel-plate modes and show numerous resonances. For typical monolithic-microwave integrated-circuit chip sizes, these unwanted resonance frequencies lie within the microwave and millimeter-wave frequency region. Due to this feedback mechanism, today's coplanar millimeter-wave amplifiers operating up to 250 GHz require special packaging techniques for stable operation. The use of vias is one method of suppressing parallel-plate modes. The effect of via-holes within a ground plane and the effect of an open or a shorted ground-plane periphery on the parallel-plate modes of CBCPWs were investigated in depth up to 200 GHz for quartz and GaAs substrates. It is shown that the placement of the vias within the coplanar-waveguide structure is crucial for the suppression of parallel-plate modes. If properly placed, vias are an effective means to suppress these unwanted modes over a chosen frequency range.

On the use of vias in conductor-backed coplanar circuits

The novel one-dimensional left-handed microstrip lines (LHMLs) consisting of the arrays of thin wires and two-layer split-ring resonators are investigated theoretically and experimentally in this paper. Unlike the conventional left-handed metamaterials for waveguides or microstrip lines, which are bulky three-dimensional constructions or require the lumped elements for high-pass configuration, this distributed structure can be directly implemented on a substrate by photolithographic techniques without soldering any chip inductors or capacitors. Moreover, it can also be easily realized at a higher frequency region by scaling the dimensions of the structure, making it highly efficient and flexible in millimeter-wave applications. To characterize the inhomogeneous LHML, the effective medium description is developed for extracting the effective electromagnetic parameters, i.e., the complex effective permittivity and permeability, as well as the refractive index. Results show that not only the simultaneously negative real permittivity and permeability, but also the antiparallel phase and group velocities may be achieved in the design passband region. In contrast to the antenna array using the conventional microstrip delay line, the LHML is incorporated in the series-fed microstrip combline array to exhibit the leading phase between the successive elements.

Effective electromagnetic parameters of novel distributed left-handed microstrip lines

A simple method and closed-form analytic formulas for symmetric CPS based on single layer substrate (infinite and finite thickness) and multilayer lossy dielectric (semiconductor) substrate, where the permittivity of the superstrate layers decrease away from the strips, are proposed. Since the line models are given analytically, the dependencies of the line parameters may be analyzed and optimized in wide ranges of sizes, permittivities, and losses (substrate resistivity). In general, the formulas are reversible. The measured line parameters may be used to calculate the permittivity and loss tangent (resistivity) of one of the substrate layers if the parameters of the other layers and strips are known. The method may be easily extended to include larger number of substrate layers.

Application notes - basic parameters of coplanar-strip waveguides on multilayer dielectric/semiconductor substrates, Part 1: high permittivity superstrates

In this paper, we present a structure called a non-leaky coplanar (NLC) waveguide with conductor backing. It is a multilayered structure with two possible configurations. The spectral domain approach with a complex root searching procedure is used to investigate leakage phenomena. The simulation results confirm that the leakage in conductor-backed coplanar waveguide (CBCPW) occurs in the form of wave in the parallel plate waveguide with infinite width. The results show that the leakage in the multilayered structure can be removed if the geometrical and material parameters of the structure are chosen appropriately. Experiments were carried out to investigate the transmission of these structures. It was found that the resonance in the transmission of finite-width conductor-backed coplanar waveguide (FW-CBCPW) is caused by the energy leakage from the dominant CPW mode. The resonance is eliminated in the NLC waveguides. These NLC waveguides are feasible and practical in the uniplanar MMIC design due to their planar nature. >

Non-leaky coplanar (NLC) waveguides with conductor backing

A new planar transponder integrating a self-oscillating mixer (SOM) and active antennas is presented. The receiving active antenna combines a FET SOM with a patch antenna and the transmitting antenna is combined with the IF amplifier. The transponder was successfully operated up to 2 m. The design concept and the experimental result are discussed. >

Transponder using self-oscillating mixer and active antenna

Analysis and application of nonleaky uniplanar structures with conductor backing

A newly developed structure, non-leaky coplanar waveguide (NLC), is used for an active antenna. Spectral domain and FDTD codes are developed to provide the design parameters. The circuit is successfully operated with an antenna gain better than the CPW design. >

Non-leaky coplanar waveguide active antenna

employed both as a resonant antenna for receiving the RF signal and for constructing the balanced mixer. In order to further minimize the complexity of the circuit, the receiving Part ofthe mansponder was designed using only one as a single ended SOM. A new planar transponder integrating a self-oscillating mixer (SOM) and active antennas is presented. The receiving active antenna combines a FET SOM with a patch antenna and the transmitting antenna is combined with the IF amplifier. The transponder was successfully operated up to 2 m. The design concept and the experimental result are discussed.

http://ieeexplore.ieee.org/iel5/1100/7886/00335423.pdf

Kimin Cha

Papers

Non-leaky coplanar (NLC) waveguides with conductor backing

Transponder using self-oscillating mixer and active antenna

Analysis and application of nonleaky uniplanar structures with conductor backing

Non-leaky coplanar waveguide active antenna

Self-oscillating mixer and active antenna