Offset Double-sided Parallel-strip Lines Research Articles

High-Efficiency Power Amplifier with a Multiharmonic Tuning Network

One high-efficiency power amplifier (PA) with a novel multiharmonic tuning (HT) network is presented. The second and third harmonic impedances are simultaneously controlled with a simple offset double-sided parallel strip line (DSPSL)-based output-matching network. Based on the above strategy, high PA efficiency can be achieved by mapping the fundamental and harmonic impedances to the optimum positions, while PA linearity can be improved through third harmonic suppression. The offset DSPSL is used to realize the transmission lines with extremely high impedance ratio in the multiharmonic trapping circuit. For demonstration, a PA using Cree CGH40010 GaN HEMT is designed with up to third harmonic control. The fabricated PA achieves peak power-added efficiency (PAE) and drain efficiency (DE) of 78.2% and 82.3%, respectively, while delivering 39.2-dBm output power at 1.8 GHz. Besides, the output third-order intercept point (OIP3) of the PA has an improvement of 3 dB.

A Patch Antenna Coupling of Periodic Leak-Wave Structure With Tri-Frequency Capability

A patch antenna coupling of a periodic leak-wave structure with tri-frequency capability is proposed. The periodic offset double-sided parallel stripline (DSPSL) leaky wave structure (LWS) is embedded in the direction of the whole ground of the microstrip patch substrate, then the capability of tri-frequency could be obtained by the different Floquet mode of the propagation constant. According to the design principle, a unified formula was derived to calculate the tri-frequency points at the same time. Though applying of antenna design principle and the simple tri-frequency formula, a tri-frequency patch antenna was designed and tested. Experiment results show that the antenna operated at 1.71, 2.05, and 2.72 GHz. The measured and calculated results show high consistency.

A Compact Planar Quasi-Yagi Antenna With Bandpass Filtering Response

A planar quasi-Yagi antenna with bandpass filtering response is presented. The quasi-Yagi antenna consists of a double-sided printed driven dipole, an offset double-sided parallel-strip line (DSPSL) director, a DSPSL reflector, and an offset DSPSL parasitic element. Both the reflector and the parasitic element can produce an extra radiation null at the band-edges of the passband, and the parasitic element can also generate an additional resonance within the passband. As a result, a compact wideband quasiYagi antenna with quasi-elliptic bandpass filtering response is obtained, without requiring any extra filtering circuit. In addition, the antenna is fed by a balanced DSPSL, and therefore, no balun is needed, leading to a very simple feeding structure. For demonstration, a prototype operating at 2.4 GHz was designed and measured. The prototype has a low profile of 0.006λ0, a -10-dB impedance bandwidth of 30.4%, an average gain of 5.7 dBi over the passband, and an out-of-band suppression level of about 20 dB in the near stopbands.

A Concurrent Dual-Band High-Efficiency Power Amplifier With a Novel Harmonic Control Network

One method to realize a concurrent dual-band (DB) high-efficiency power amplifier (PA) with a novel harmonic control network is presented. The same structures are used in harmonic trap and biasing circuits, which largely simplify the design procedure. The proposed harmonic control network can transfer the optimum fundamental and second-harmonic impedances of the transistor to 50 $\Omega $ load simultaneously at the two desired frequencies. Offset double-sided parallel strip lines are introduced to realize the high impedance lines in the harmonic trap and biasing circuits. For demonstration, a PA using Cree CGH40010 GaN HEMT is designed at 1.9 and 3.3 GHz with up to second-harmonic control. The realized DB PA achieves a peak power-added efficiency of 78.5% and 76.7%, respectively, while an output power of 39.9 and 39.3 dBm are delivered by the PA at the measured frequencies of 1.84 and 3.22 GHz.

Broadband SIW Horn Antenna Loaded With Offset Double-Sided Parallel-Strip Lines

A novel substrate integrated waveguide horn antenna loaded with offset double-sided parallel-strip lines (DSPSL) is proposed in this letter. The severe mismatch between horn aperture and free space leads to narrow impedance bandwidth when the substrate thickness is much smaller than the wavelength (typically less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\lambda _0}$</tex-math></inline-formula> /6). Two groups of periodic offset DSPSL structure are placed in front of the horn aperture, which acts as an impedance transformer to realize smooth transition. Good impedance matching can be easily realized by modifying the constitutive parameters of the offset DSPSL structure. Measured results show that the impedance bandwidth can be improved up to 20.5% from 14 to 17.2 GHz with a low profile less than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda _0}$</tex-math></inline-formula> /13. Stable end-fire radiation patterns are obtained across the bandwidth.

A Simple Method of Designing High-Efficiency Second-Harmonic-Tuned Power Amplifier

This letter presents a simple method to realize high-efficiency second-harmonic-tuned (2HT) power amplifier (PA). Compared with other works, this method can realize optimum fundamental and second-harmonic impedance matching accurately, thus to achieve a relatively high efficiency through only controlling the first two frequencies. Besides, to avoid the problem of transmission line with high characteristic impedance in traditional dual-band bias network, offset double-sided parallel-strip line is introduced. For demonstration, a PA using Cree CGH40010 GaN HEMT is designed and fabricated. The measured peak power added efficiency and drain efficiency reach 80.4% and 84.2%, respectively, with a corresponding output power and gain of 40.4 dBm and 13.4 dB at 2 GHz under continuous wave signal.

A Broadband Offset-Parallel-Parallelograms Printed Endfire Antenna

A broadband offset-parallel-parallelograms printed endfire antenna is presented. The proposed antenna consists of a pair of offset parallel parallelograms, the driver dipoles, the offset double-sided parallel-strip line, and a reflector. The top and bottom patches are printed in parallel on two sides of a substrate plane. The characteristics of the offset parallel parallelograms are studied and discussed. The calculated results fit in well with the results obtained by simulation with ANSYS HFSS. The broadband endfire radiating patterns were achieved. The measured bandwidths were 73.3% for the frequency band (0.89-1.92 GHz), and the gain was about 3.3-4.8 dBi in the operating band.

Dual‐band GaN power amplifiers with novel DC biasing networks incorporating offset double‐sided parallel strip line

This study presents a novel dual-band DC biasing network and its application in the design of GaN power amplifiers (PAs). By integrating offset double-sided parallel strip line which can easily realise high characteristic impedance and thus narrow microstrip line, the proposed biasing network can obtain much higher operation frequency ratio than the conventional design. To demonstrate the new methodology, two dual-band GaN PAs applying the presented dual-band DC biasing network are implemented. The operation frequencies are 1.8/3.5 and 0.9/3.5 GHz. Three-section networks for complex load are used for dual-frequency input and output matching. Good agreement between the simulation and measurement is observed, which fully demonstrate the feasibility and validity of the presented DC bias networks in power amplifier designs.

A Dual Frequency Microstrip Antenna Using a Double Sided Parallel Strip Line Periodic Structure

A dual-frequency microstrip antenna is presented. The proposed antenna consists of a rectangular radiating patch, the ground, and a periodic offset double-sided parallel-strip line structure that is used as the substrate. The phase constant of the substrate is less than 0 at the frequency of operation, which makes the rectangular microstrip antenna work in different modes, and has two resonant frequencies. Experimental results show that the proposed antenna works at 3.3 GHz and 3.9 GHz.

The Backfire-to-Broadside Symmetrical Beam-Scanning Periodic Offset Microstrip Antenna

A backfire-to-broadside beam-scanning antenna with a periodic structure is described. The proposed antenna consists of the offset double-sided parallel-strip lines (DSPSL). The characteristics of the offset DSPSL have been studied, and then a series of offset DSPSL have been applied as the periodic antenna with a backfire-to-broadside symmetrical beam scanning capability. Both in plane and plane, main beams symmetrically steer from the backfire direction to the broadside direction with the increase of the operating frequency. The fractional impedance bandwidth has been broadened to nearly 50% by using the offset DSPSL structure.

Formula Derivation and Verification of Characteristic Impedance for Offset Double-Sided Parallel Strip Line (DSPSL)

Double-sided parallel strip line (DSPSL) is a versatile microwave transmission line. With an offset, it allows for large variations of the characteristic impedance and therefore flexibility for the design of novel microwave devices. In this letter, a formula for the characteristic impedance of DSPSL is derived by the fuzzy EM method and verified by commercial software. Very good agreement is observed.

Novel 5:1 Unequal Wilkinson Power Divider Using Offset Double-Sided Parallel-Strip Lines

A novel 5:1 unequal Wilkinson power divider using the offset double-sided parallel-strip lines (DSPSL) is proposed. High characteristic impedance is realized by offsetting the top and bottom strips of the DSPSL, which cannot be achieved using other conventional transmission lines such as microstrip line due to its fabrication limitation. The quarter guided wavelength of the offset DSPSL has been analyzed for the proposed power divider design. The simulated and measured results are presented to verify our proposed idea

Lowpass filter using offset double-sided parallel-strip lines

A novel lowpass filter using offset double-sided parallel-strip lines (DSPSL) is proposed. The proposed lowpass filter has the advantages of enhanced stopband and high power-handling capability compared with the conventional microstrip lowpass filter, because the high impedance is realised by offsetting the top and bottom strips of DSPSL without decreasing the width of strips. The theoretical and measured results are presented.