Antenna Systems & Technology - Fall 2015 - (Page 16)

FEATURE ARTICLE Tunable and Fixed Filtering Solutions Enhance Dynamic Range of 4G-LTE Measurements By Rafi Hershtig, VP of Engineering and Applied R&D - K&L Microwave 4G network integrators are demanding multiple RF tests requiring high dynamic range and versatility. The continuous evolution of LTE bands presents a challenge to design engineers, who must develop products and, in concert, provide for rigorous testing. PIM, meaning the passive intermodulation product due to two carriers in the transmit band yielding products in the receive band, is the leading requirement dictating the level of dynamic range needed for proper testing. Dynamic range of PIM test setups ranges from -161 dBc for two +43 dBm tones (for filters, couplers, cables, etc.) to -140 dBc for antennas. 4G's increased data rates pushed PIM vulnerabilities even lower, making PIM the benchmark for determining the health of cell sites and cellular equipment. PIM contributors at the cell site and at the manufacturing stage are receiving increasing coverage in the literature due to their influence on quality of service and operator revenue. In addition to PIM measurements, important RF testing requirements include Harmonic Products, Load-Pull Test, GPS Products and IMD (Inter-Modulation Distortion) Products due to Jammer (Blocker) Signals, to name a few. Not all measurements call for the high dynamic range of PIM setups, but convenience, efficiency, cost factors and absence of push-button solutions have led engineers to build their own test setups with as many general-purpose components as possible. This article presents new block diagrams based on tunable and fixed filters to provide high dynamic range and versatility, yielding systems that can measure across multiple LTE bands and be expanded in "plugand-play" style. Design Guidelines of Multiple Band Test Setup with Enhanced Dynamic Range * Prevent energy from bouncing back to the device under test (DUT). By providing wideband matching, energy traveling from the DUT is terminated. * Avoid ferromagnetic components, such as isolators/circulators, in signal paths to and from the DUT. Any unnecessary mixing yields IMD products that will degrade the final reading. Reducing IMD sources outside the DUT increases the certainty and stability of results. * Shorten the path where fundamental signals are mixed to reduce secondary IMD sources. * Avoid attenuators, as their impact on desired signals reduces dynamic range. Figure 1. Emission Monitoring Using HP/LP and BP/BS Duplexers Fixed and Tunable Components Filtering solution building blocks for multiple band test setups come in fixed and tunable forms. Fixed filter components appeared first. The benefits of using fixed filter building blocks to design test systems are well established in segments of our industry. With increasing demand for fast and accurate RF measurements for 4G-LTE protocols, novel tunable filtering schemes 16 Antenna Systems & Technology Fall 2015 Figure 2. Emission Monitoring Using BP Triplexer Figure 3. Emission Monitoring Using BP/BS Quadraplexers www.AntennasOnline.com http://www.AntennasOnline.com

Table of Contents for the Digital Edition of Antenna Systems & Technology - Fall 2015

Editor’s Choice
Dual Tuning - The OEM's Secret Weapon in Spectrum Proliferation
A Hybrid "Hexa-Band" Cellular Antenna
Tunable and Fixed Filtering Solutions Enhance Dynamic Range of 4G-LTE Measurements
Antenna Systems 2015: Conference Preview
Low-Cost and Frequency-Selective Metamateiral and Its Antenna Applications
Antennas
Components/Subsystems
Software / System Design
Industry News
Hiding a DAS
Marketplace

Antenna Systems & Technology - Fall 2015