Single-ended Antenna Research Articles

Active differential reflection coefficient analysis of differentially-fed antenna array

In this paper, a definition for the active differential reflection coefficient of the differentially-fed antenna array is proposed. Each antenna is fed by the differential port with the equal-amplitude anti-phase signal input. According to the active reflection coefficient of the conventional single-ended antenna array, the active differential reflection coefficient definition of the differential antenna array is given and analyzed. It is derived that the active differential reflection coefficient of the differential port m is half of the active reflection coefficient sum for the single-ended port m + and m −. In addition, the active differential impedance expression is also given. To verify the active differential reflection coefficient, a differential three-element microstrip patch antenna array was designed, fabricated, and measured. The experimental results validate the proposed theoretical analysis. This work will provide a new insight into the differential antenna array.

Four-Node Antenna Feeding Network for Interfacing With Differential Front-End Electronics

A novel concept of a differential feeding network for four-node antenna/antenna arrays is proposed. The network is constructed out of a four-strip coupled-line directional coupler operating in a mixed differential-nodal mode enabling direct interfacing of differential front-ends with single-ended antennas. It is shown, that such a configuration provides at the outputs of the proposed feeding network four signals, which are equal in amplitude and with phase progression of 90°. Thus, such a network can be utilized for generating either dual-circular polarization from a 2× 2 antenna array or can constitute simultaneously two out-of-phase power dividers and a directional coupler resulting in a two-beam antenna array in one cut-plane and two-element array in the other one. The dual-circular excitation is of particular interest for modern-day transceivers as it enables polarization-division-duplex communication. The presented concept is confirmed by measurements of two different antenna arrays operating at 2.5 GHz frequency range featuring dual-circular and dual-beam properties, respectively.

Analysis of an Enhanced-Q N-Path Filter with Improved Even-Order Harmonic Rejection

Based on a feedback system, an N-path bandpass filter robust to even-order harmonic mixing (BPF-REHM) is presented. BPF-REHM consists of a conventional differential N-path filter around a gain stage. Despite assuming a single-ended antenna, this work aims at partial rejection of even-order harmonics before the signal travels through the baseband circuitry. Linear periodically time-varying analysis of the new filter is presented. Mathematical derivations verify an enhanced-Q filtering behavior in addition to even-order harmonic rejection at RF nodes. Drawback of BPF-REHM, i.e., input impedance mismatch, is addressed by proposing a two-stage LNA. The second stage of the new LNA, which is the BPF-REHM, suppresses even-order harmonic blockers while the first stage matches the input to the source and provides enough gain to accomplish an acceptable overall noise performance. The design example is a 500?MHz four-path filter simulated with the 90?nm CMOS. It achieves >22?dB even harmonic rejection with an enhanced-Q filtering characteristic thanks to the new technique. Besides, this design achieves 21?dB gain, 2?dB NF, and $$+$$+2.5?dBm out-of-band IIP3 at 50?MHz offset while consuming 8.3?mW of power.

An Energy-Efficient All-Digital UWB Transmitter Employing Dual Capacitively-Coupled Pulse-Shaping Drivers

This paper presents an all-digital, non-coherent, pulsed-UWB transmitter. By exploiting relaxed center frequency tolerances in non-coherent wideband communication, the transmitter synthesizes UWB pulses from an energy-efficient, single-ended digital ring oscillator. Dual capacitively coupled digital power amplifiers (PAs) are used in tandem to attenuate low frequency content typically associated with single-ended digital circuits driving single-ended antennas. Furthermore, four level digital pulse shaping is employed to attenuate RF sidelobes, resulting in FCC compliant operation in the 3.5, 4.0, and 4.5 GHz IEEE 802.15.4a bands without the use of any off-chip filters or large passive components. The transmitter is fabricated in a 90 nm CMOS process and occupies a core area of 0.07 mm2 . The entirely digital architecture consumes zero static bias current, resulting in an energy efficiency of 17.5 pJ/pulse at data rates up to 15.6 Mb/s.

A Fully Integrated UHF CMOS Power Amplifier for Spacecraft Applications

A power amplifier (PA) is designed for a surface-to-orbit proximity link microtransceiver on Mars exploration rovers, aerobots, and small networked landers and works in conjunction with a 0.2-dB loss transmit/receive switch to allow nearly the full 1 W to reach the antenna. The fully integrated UHF CMOS PA with more than 30-dBm output is reported for the first time. A differential pMOS structure with floating-bias cascode transistors and 1:3-turn ratio output transformer are chosen to overcome low breakdown voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bk</sub> ) of CMOS and chip area consumption issues at UHF frequencies. The high-Q on-chip transformer on a sapphire substrate enables the differential PA to drive a single-ended antenna effectively at 400 MHz. The PA in a standard package delivers 30-dBm output with 27% power-added efficiency. No performance degradation was observed in continuous-wave operation and the design has been tested to 136% of its nominal 3.3-V supply without failure.

A new concept for front‐end circuit integration: From single‐ended antenna to differential‐input connection without any external balun

AbstractA new concept for a single‐ended input front‐end circuit design is proposed. The coupling of a single‐ended low‐noise amplifier (LNA) to a double‐balanced cross‐coupled mixer using a single‐to‐differential transformer is successfully implemented and then tested in the 5.725–5.825‐GHz band in order to show its feasibility. Furthermore, this idea is even useful for wide‐receive‐band applications when the bandwidth of the LNA is designed widely. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 1–4, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21063