1.85mm Connector (V)
Understanding the 1.85mm Connector
In the 1980s, the push for millimeter-wave technology required components that could operate above 50 GHz. While smaller connectors existed, they were notorious for breaking; the center pins would snap, or the outer walls would crush under torque. The 1.85mm connector was engineered by Hewlett-Packard (now Keysight) to provide extreme frequency performance in a mechanically rugged package.
Mechanical Superiority
The "1.85mm" designation refers to the inner diameter of the outer conductor. To maintain a $50 \Omega$ impedance in an air-dielectric medium, the center pin is a highly delicate 0.803mm thick.
However, the genius of the 1.85mm connector lies in its housing:
- The outer conductor wall is aggressively thickened compared to legacy SMA designs.
- When mating, the heavy outer conductors engage and perfectly align before the fragile inner center pins ever touch.
- This "outer-first" mating geometry makes it nearly impossible to accidentally bend or snap the center pin by inserting it at an angle.
Cross-Mating Compatibility
| Connector Type | Compatibility with 1.85mm | RF Consequence |
|---|---|---|
| 2.4mm Connector | Perfectly Mateable. | The 1.85mm and 2.4mm connectors share the exact same thread pitch (M7 x 0.75) and a compatible pin geometry. Mating them is electrically safe, though the performance of the joint will be limited to the 50 GHz cutoff of the 2.4mm side. |
| 2.92mm (K) / SMA / 3.5mm | Destructively Incompatible. | If you attempt to thread an SMA or 2.92mm connector onto a 1.85mm port, the threads will physically cross and bind. More importantly, the center pin of the SMA is massively oversized and will instantly crush the delicate fingers of the 1.85mm female receptacle, permanently destroying it. |
Frequently Asked Questions
Why is it called the V-Connector?
The 'V' designation is a commercial trademark originally introduced by Anritsu. It denotes the connector's intended operating band (the V-Band, roughly 50 to 75 GHz). While 'V-Connector' is heavily used in the industry, 1.85mm is the open IEEE 287 standard name.
Does the 1.85mm use Teflon?
Not in the mating interface. It uses an 'air dielectric' interface for maximum performance. Further back inside the connector body, a highly specialized, ultra-thin dielectric bead (often made of Ultem or Rexolite) is used to physically suspend the center pin in the middle of the air gap, but it is engineered to be electromagnetically invisible.
What is the proper torque for a 1.85mm connector?
Because the threads are much larger and more robust than an SMA, the 1.85mm connector is torqued to 8 in-lbs (0.90 N-m). This high torque guarantees the outer mating faces crush together flat, eliminating the microscopic air gaps that cause VSWR spikes at 60 GHz.