Lumped-Element Balun for UHF UWB Printed Balanced Antennas

Abstract

Abstract-A semi-lumped balun transformer for UHF and ultrawideband (UWB) dipole antennas is presented in this paper. The proposed structure is based on two asymmetric filters that also transform the variable antenna impedance into the desired source impedance. These asymmetric filters make use of a binomial impedance transformer in each filter section. The asymmetric filters (one low pass filter, LPF, and other high pass filter, HPF) allow the balun bandwidth to be increased while the binomial transformer matches the variable balanced dipole impedance. In this way the ripple in the balun response due to the variation of the UWB dipole impedance is reduced. A balun for a UHF and UWB dipole antenna working from 220 to 820 MHz (bandwidth of 4:1) has been achieved with losses lower than 1 dB. These types of baluns are particularly useful in the low microwave frequency band.

A new compact ultra-wideband balun for printed balanced antennas

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] To reduce the circuit dimension, baluns using low-temperature co-fired ceramic technology and Complementary Metal Oxide Semiconductor (COMS) technologies were presented in [1,2], respectively, yet the multilayer process increases the complexity and the cost of the circuits. In [3,4], lumped-element baluns were introduced with compact size, while they could not realize wide bandwidth due to inherent characteristic of lumped elements. Based on microstrip Marchand balun prototype, baluns with good performance [5][6][7] have been designed.…”

Compact Two-Section Half-Wave Balun Based on Planar Artificial Transmission Lines

“…Owing to the output balanced amplitude characteristic with its phase difference of 180 degrees, it is a key component in balanced circuit topologies, such as balanced antennas and balanced mixers. Various balun configurations have been reported for applications in microwave circuits, such as coupled-line baluns, composite right/left-handed (CRLH) transmission line baluns, Wilkinson power divider baluns, three-line baluns, microstrip taper baluns, and lumped baluns [1][2][3][4][5].…”

Circular Dipole Antenna for Mode 1 UWB Radio With Integrated Balun Utilizing a Flex-Rigid Structure

“…In the rigid part other circuitries are designed and placed as with any other type of regular multi-layer printed circuit boards. To connect the dipole antenna to a 50-Ω single-ended port a balun is needed, and traditionally the balun is built with lumped components [23], [24]. However, in this paper the dipole antenna balun is realized with distributed components and integrated in the rigid part.…”