Drasko Draskovic

Varactor tuned dual-band Wilkinson power divider

The design and performance of varactor tuned dual-band power divider circuit have been presented. The coupler is tunable from 950 to 1150 MHz and from 2300 to 2500 MHz and it shows return loss of at least 15 dB and coupling of 3±0.5 dB across each band.

Frequency switchable dual-band branch-line couplers

In this paper, silicon switches are implemented in the design of frequency switchable dual-band branch-line coupler. Frequency switching is achieved by increasing the power of the laser applied to the highly resistive silicon wafer and changing the properties of silicon under optical illumination. The advantages of this approach are high-speed switching, electromagnetic transparency (no interference) and thermal and electrical isolation between the coupler and the control circuit. A frequency shift of 35% and 10% has been achieved from all switches off to all switches on in lower (900 MHz) and upper (1800 MHz) frequency bands, respectively.

Optically reconfigurable matching networks

In this paper an optically reconfigurable circuit as a part of the input matching network is proposed and applied in order to design a 2.5-3.5 GHz frequency tunable power amplifier. Tunability is achieved by increasing the power of the laser applied to the highly resistive silicon wafer and changing the properties of silicon under optical illumination. Tunable class AB power amplifier with the optical switch in the input matching circuit has obtained the frequency tuning range of 2.5-3.5 GHz with no significant loss in efficiency and linearity.

Quad-band power dividers with generalized NRI metamaterial transmission lines

The design and performance of a quad-band power divider circuit with generalized NRI-TLs have been presented. The coupler covers 850, 1350, 2500 and 2900 MHz bands and it shows return loss of at least 15 dB and coupling of 3±0.5 dB across each band.

Microstrip patch antennas with harmonic rejection using composite right-left handed transmission lines

In this paper a 2.4 GHz patch antenna with improved performance was designed, using harmonic tuner with Composite Right/Left-handed (CRLH) transmission lines. Composite Right-Left Handed (CRLH) transmission line was modelled as a periodic structure with infinitesimal unit cells. The unit cell consists of a RH series inductance LR and shunt capacitance CR (conventional transmission line) and LH series capacitance CL and shunt inductance LL.

An optically reconfigurable dual-band branch-line coupler with artificial transmission lines

This paper demonstrates switches that achieved a frequency shift of 30% from all switches off to all switches on in both frequency bands. This study shows the advantages of this approach such as high-speed switching, electromagnetic transparency, and thermal and electrical isolation between the coupler and the control circuit. The use of the artificial transmission lines significantly decreases the overall size of the circuit.

A dual-band 6-port quasi-Composite Right-Left Handed Branch-line coupler

In this paper the quasi-CRLH dual-band coupler was embedded into six-port front-end architecture (Nguyen, 2006) and realized in microstrip technology. The advantages of this solution are: multiport DB (can be used in both transmitter and receiver and dual-band operation - GSM 900MHz, 1.8GHz), relatively compact circuit size and easy fabrication.

Design of LDMOS Balanced Power Amplifiers with Improved IMD Performance and Size Reduction

An LDMOS class-AB balanced power amplifier with an attempt to use reduced-size branch-line couplers in the divider/combiner parts is presented. The proposed amplifier with a center frequency of 2.14 GHz was designed. At center frequency a size reduction and improved intermodulation distortion are achieved, comparing with the conventional branch line couplers.