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Low PIM Components: The Real Engineering Math From link budget to selection traps
Jun , 16 2026
Anyone who has worked on distributed antenna systems will eventually have a head‑on fight with PIM. This post skips the fluff and only shows the engineering math. 1. Where PIM comes from — the formula Two frequencies f1, f2 pass through a non‑linear node (loose connector, oxidized plating, magnetic material) and generate intermodulation products: 3rd order: 2f1－f2 , 2f2－f1 5th order: 3f1－2f2 , 3f2...
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PIM Interference vs. External Interference: How to Quickly Tell Them Apart On‑Site?
Jul , 07 2026
Anyone who does base‑station maintenance or network optimisation eventually runs into this: uplink noise floor spikes, users complain about dropped calls and low throughput, yet VSWR tests pass and there are no equipment alarms. Where is the problem? At this point, you have two possible culprits – PIM (passive intermodulation) interference generated inside your own system, or external RF interfere...
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5 Ways a Bad Passive Component Can Ruin Your DAS Link Budget
Jul , 14 2026
Designing a DAS link budget is an exercise in controlled optimism. You calculate cable loss per 100 meters, add up splitter and coupler insertion loss, account for connector transitions, and leave a few dB of margin for things you can't control. Then you order the components, install the system, and turn it on. And the numbers don't match. Not by a little. By 6, 8, sometimes 10 dB. Coverage holes ...
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4G Internal Antenna vs External Antenna: How to Choose the Right LTE Antenna
Jul , 21 2026
During the design of 4G LTE communication equipment, antenna selection is often one of the most critical decisions affecting wireless performance. For equipment manufacturers, system integrators, and wireless solution providers, a common question keeps coming up: Should I choose a 4G internal antenna or a 4G external antenna? Many engineers fall into a simple trap early in a project: “External ant...
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Combiner vs Duplexer: Not the Same Thing — A Complete Engineering Guide
Jul , 28 2026
Combiner and duplexer are not the same thing. A combiner is a device that merges two or more RF signals into a single output path, with all signals flowing in the same direction — primarily used for power combining on the transmit side. A duplexer is a three‑port device that isolates transmit and receive signals, allowing them to share a single antenna, with the two signal paths flowing in opposit...
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4x4 Hybrid Combiner 698-2700MHz: The Engineering Guide
Sep , 01 2026
What Is a 4x4 Hybrid Combiner and Why Does It Matter? A 4x4 hybrid combiner is a passive RF device that evenly distributes a signal from any of its four input ports to all four output ports, while maintaining high isolation between ports. Think of it as a signal router that takes whatever goes into one port and splits it equally (with a 6dB theoretical loss) to all four outputs, but prevents signa...
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Three 10dB Couplers Compared: Insertion Loss and PIM Test Results – Cavity vs Microstrip vs Stripline
Sep , 29 2026
In DAS indoor distribution systems and RF link designs, the 10dB directional coupler is one of the most frequently used passive components. The two specifications engineers care about most are insertion loss and passive intermodulation (PIM) — the former directly eats into the link budget, the latter determines whether the uplink noise floor can be kept down. There are three main manufacturing tec...
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