Design Compact ESP32-S3 RF Hub

I am looking for an experienced **PCB/RF engineer** to redesign an existing working prototype into a compact, production-ready industrial PCB.

The existing electronics and firmware architecture are already functional. The selected engineer will receive detailed schematics, connection information and additional technical documentation after selection / NDA.

The main task is **hardware miniaturization, RF design, schematic design and PCB layout**.

## Main Hardware Requirements

The PCB will include:

* 4x compact ESP32-S3 IC implementations
* 4x independent 2.4 GHz RF sections
* Wired internal communication between the four ESP32-S3 devices
* LTE connectivity
* 433 MHz RF section
* 2x compact relays
* Protected digital/sensor inputs
* Wide-input AC/DC power supply
* USB-C programming/debugging
* Compact industrial design

## 2.4 GHz RF Requirements

Each ESP32-S3 must support:

* 1x onboard high-quality 2.4 GHz ceramic/chip antenna
* 1x optional U.FL/IPEX connector for an external 2.4 GHz antenna
* Proper antenna-selection method so only one RF path is active
* RF matching network
* 50-ohm controlled impedance routing
* Correct RF keep-out areas
* Proper grounding
* Provision for antenna tuning/testing

Total:

* 4x ESP32-S3
* 4x ceramic 2.4 GHz antennas
* 4x optional U.FL/IPEX antenna connections

The normal configuration should use the ceramic antennas, while the U.FL connections provide external-antenna capability when required.

A key part of the project is correctly designing **four nearby 2.4 GHz RF sections on the same compact PCB**.

The engineer should understand:

* Mutual antenna coupling
* Receiver desensitization
* RF isolation
* Ground-plane/surface-current coupling
* Antenna placement and orientation
* Matching networks
* S11 / S21 measurements
* VNA-based RF validation
* Multi-radio PCB design

## LTE

The PCB must include:

* Compact LTE module suitable for Europe
* Nano SIM
* External LTE antenna connector
* Proper LTE power supply
* Filtering and decoupling

I am open to recommendations for a suitable compact LTE Cat 1 / Cat 1 bis module.

## 433 MHz

The board must include:

* Dedicated 433 MHz RF section
* Suitable transceiver/receiver
* Dedicated external antenna connection
* Proper filtering and RF separation

## Relays and Inputs

The PCB must include:

* 2x compact relays
* Dry-contact relay outputs
* Protected field inputs for external sensors

Exact I/O details will be provided to the selected engineer.

## Power Supply

The board must accept approximately:

**5–60 V AC/DC**

from a single power input.

The design should include:

* Bridge rectification
* Input protection
* Surge/transient protection
* Filtering
* Wide-input voltage regulation
* Required low-voltage rails

Important: the design must correctly account for the peak DC voltage resulting from high AC input voltage.

## USB-C Programming

The PCB should have **one USB-C programming/debug connector** capable of selecting between the four ESP32-S3 devices.

Concept:

**ONE USB-C → SELECT NODE → PROGRAM SELECTED ESP32-S3**

A compact selector, multiplexer or other reliable implementation may be proposed.

## PCB Size

Preferred shape:

**RECTANGULAR**

Initial target:

**approximately 100 × 60 mm**

This is a target, not a strict limitation.

A smaller PCB is welcome if RF performance, safety, thermal performance and manufacturability remain good.

The engineer should recommend the appropriate PCB layer count.

## Connectors

External screw terminals should be aligned cleanly along one PCB edge and grouped logically by function.

The final board should be easy and clean to install in industrial automation enclosures.

## Manufacturing

The PCB should preferably be optimized for **JLCPCB/LCSC assembly**.

Components should be realistically available for production.

## Required Deliverables

I need a complete manufacturing-ready project including:

* Complete schematic
* Complete PCB layout
* Editable source files
* Gerber files
* BOM
* CPL / Pick-and-Place files
* JLCPCB-ready production package
* Manufacturer part numbers
* LCSC part numbers where possible
* RF matching details
* Antenna component details
* DRC / DFM checks
* Programming/debug documentation
* One reasonable revision after first prototype review

I require the editable source project, not only Gerbers or PDFs.

## Existing Prototype

A working prototype already exists and performs very well.

This is therefore **not a concept-from-zero project**.

The objective is to create a smaller, cleaner, professionally engineered and production-ready PCB while preserving the proven system architecture.

Detailed system operation, firmware architecture, PCB photos and current hardware information will be provided to the selected engineer.

## Please Include in Your Proposal

1. Examples of ESP32 / RF / LTE PCBs you personally designed.
2. Experience with bare ESP32-S3 PCB designs.
3. Experience with ceramic/chip 2.4 GHz antennas.
4. Experience designing multiple 2.4 GHz radios on the same PCB.
5. How you would reduce mutual coupling and receiver desensitization.
6. How you would validate antenna matching and isolation.
7. Whether you have access to a VNA or other RF measurement equipment.
8. Your recommended PCB size and layer count.
9. Your recommended LTE module.
10. Confirmation that you can design the 5–60 V AC/DC power input.
11. Your fixed total project price.
12. Estimated delivery time.