Molex Antenna Adventures starring a RPi4

18 Nov 2020

Some time ago, I received a Molex Antenna Kit consisting of a boatload of different antenna types. A big thanks to E14, Avnet and Molex.

These are the contents:

{gallery}Molex Antenna Kit
Antenna Kit: Molex Sample Kit
Antenna Kit: Cellular Antennas
Antenna Kit: Combo Antennas
Antenna Kit: GNSS Antennas
Antenna Kit: ISM Antennas
Antenna Kit: NFC Antennas
Antenna Kit: UWB Antennas
Antenna Kit: BT/WiFi Antennas
Antenna Kit: Selection of WiFi Antennas

{gallery}Molex Antenna Kit

Antenna Kit: Molex Sample Kit

Antenna Kit: Cellular Antennas

Antenna Kit: Combo Antennas

Antenna Kit: GNSS Antennas

Antenna Kit: ISM Antennas

Antenna Kit: NFC Antennas

Antenna Kit: UWB Antennas

Antenna Kit: BT/WiFi Antennas

Antenna Kit: Selection of WiFi Antennas

As a leftover from a previous roadtest, I am also the proud owner of a PaspberryPi4 B. This mighty little computer did have bad WiFI performance in the basement, with the router being one floor up and across the house.

A close look at the board shows a very interesting layout for the PCB antenna. I don't even want to start thinking about, what is going on there in the RF domain.

The part that interested me most, was the empty footprint at the feed trace and the single contact, suggesting a mounting option for an UMC connector. The antenna Kit did contain a nice selection of dual band 2.4/5 GHz WiFi/Bluetooth antennas with UMC connections as well. One Digikey order later, a fitting part ended up on my desk. In the spirit of the giveaway, it is a Molex UMC receptable 50 Ohm SMD, part number 073412-0110.

A banana for scale would not work very well, so I used my EEVblog measuring stick.

The next steps are: cut trace, add wire bridge, scrape scrape scrape, solder connector in place, plug in antenna, done.

One of the camera connector slots in the housing is a perfect feed-through to get the antenna out. And there is 'plenty' of room to stick it somewhere to secure it.

A quick test, did reveal an improvement in WiFi signal strength.

= .

I am sure, there is some programs around to give more detailed WiFi signal strength information, but I am happy as it is. So no 'apt get ..........' session tonight, that would take longer than the hardware upgrade.

The End.

PS: I probably should scratch the FCC/CE mark off the board now...

Top Comments

wolfgangfriedrich over 4 years ago

It looks like the RPi Foundation went with my idea for their compute module:

Must be a fancy RF switch.

From:
https://www.raspberrypi.org/products/compute-module-4-antenna-kit/?resellerType=home
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wolfgangfriedrich over 4 years ago in reply to colporteur

Thanks for the kudos, much appreciated.
I just could not pass that opportunity with the branch off and connector pad. If I can see it, I can solder it.
- W.
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colporteur over 4 years ago

I sit here on Friday night with two Coors Light beers in my gullet and think WOW!

I doff my hat for your initiative. I have no fortitude for putting a Pi at risk by hacking to the level you have ventured. My first RoadTest application New Year's Grab Bag RoadTest was an appeal to sacrifice a RoadTest review Pi first version generation to test an interface. I feared for the life of my Pi3B+ during testing but was willing to let go a Pi first generation.

I received a similar antenna kit you received but I didn't get the enlightenment of possibilities you got. Great work WF, great work!
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wolfgangfriedrich over 4 years ago in reply to wolfgangfriedrich
jkutzsch:
I have some more results: as expected, unplugging the new antenna really kills the Wifi range. It detects the network up to 2 meters away from the router in line of sight or through a thin North-american wall with the router right next to the wall. Everything further away ends up with a un-connected RPi.

And I learnt another Linux command:
```
sudo iwlist wlan0 scan
```
outputs a lot of stats about the network including signal strength in dB.
This can be useful to characterized WiFi coverage.
The output is in the form of:
```
Channel:157
Frequency:5.785 GHz (Channel 157)
Quality=45/70  Signal level=-65 dBm  
Encryption key:on
ESSID:"FibreOP444-5"
Bit Rates:6 Mb/s; 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s
          36 Mb/s; 48 Mb/s; 54 Mb/s
```
This is going to help for some future tests. Now let's build a turn table or source the lazy Susan from the kitchen cabinet.

- W.
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wolfgangfriedrich over 4 years ago in reply to jkutzsch

Hello jkutzsch.
It never occurred to me to test the RPI without antenna at all. I will do this and report back. I would imagine the feed trace + connector will not have a lot of gain. Using a generic connector like an edge-mount SMA looks possible, when you don't mind losing the mounting hole. The PCB antenna (and my setup probably too) is definitely very directional. Thanks,
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