Engineering and technology notes

Inverted-F antenna

An inverted-F antenna is a type of antenna used in wireless communication, mainly at UHF and microwave frequencies. It consists of a monopole antenna running parallel to a ground plane and grounded at one end. The antenna is fed from an intermediate point a distance from the grounded end. The design has two advantages over a simple monopole: the antenna is shorter and more compact, allowing it to be contained within the case of the mobile device, and it can be impedance matched to the feed circuit by the designer, allowing it to radiate power efficiently, without the need for extraneous matching components.

The inverted-F antenna was first conceived in the 1950s as a bent-wire antenna. However, its most widespread use is as a planar inverted-F antenna (PIFA) in mobile wireless devices for its space saving properties. PIFAs can be printed using the microstrip format, a widely used technology that allows printed RF components to be manufactured as part of the same printed circuit board used to mount other components.

PIFAs are a variant of the patch antenna. Many variants of this, and other forms of the inverted-F, exist that implement wideband or multi-band antennas. Techniques include coupled resonators and the addition of slots.

Source: Inverted-F antenna – Wikipedia

Inverted-F antenna was last modified: August 19th, 2024 by Jovan Stosic

What is the best way of connecting 2 pcb boards together

  1. Pin Headers and Sockets:
    • Description: This involves soldering a male pin header onto one PCB and a female socket onto the other.
    • Pros: Easy to connect and disconnect; provides a strong mechanical connection.
    • Cons: Takes up more vertical space; may require alignment during assembly.
  2. Ribbon Cables:
    • Description: Ribbon cables use flat cables with multiple wires to connect between two PCBs.
    • Pros: Flexible and can connect boards that are not directly aligned; good for parallel connections.
    • Cons: Can be bulky; requires connectors on both boards.
  3. Flexible Flat Cables (FFC) or Flexible Printed Circuit (FPC):
    • Description: These are thin and flexible cables that are soldered or clamped to each PCB.
    • Pros: Highly flexible, ideal for compact spaces; lightweight.
    • Cons: Can be fragile; requires careful handling during assembly.
  4. Board-to-Board Connectors:
    • Description: These are connectors specifically designed to join two PCBs. They come in various configurations, such as mezzanine, coplanar, or orthogonal.
    • Pros: Reliable and robust connections; available in many sizes and pin configurations.
    • Cons: More expensive; specific design requirements.
  5. Edge Connectors:
    • Description: One PCB has edge connectors that fit into a slot on the other PCB.
    • Pros: Allows easy swapping of boards; commonly used in modular designs.
    • Cons: Requires precise alignment and design; may wear out with repeated use.
  6. Soldered Wires:
    • Description: Directly soldering wires between the two boards.
    • Pros: Simple and cost-effective; good for permanent connections.
    • Cons: Less flexible and can be prone to breaking if moved frequently.
  7. Wireless Connections:
    • Description: Using wireless technologies like Bluetooth, Wi-Fi, or Zigbee to communicate between boards.
    • Pros: No physical connectors needed; ideal for remote connections.
    • Cons: Requires additional components and power; potential for interference and latency.

When choosing a method, consider the electrical requirements, mechanical constraints, and environmental factors your project might face. For instance, if you need to frequently disconnect the boards, a pin header might be more suitable, whereas for compact devices, FPC might be a better choice.

Source: ChatGPT

What is the best way of connecting 2 pcb boards together was last modified: August 6th, 2024 by Jovan Stosic

WebSockets on nginx

location /api/websocket {
proxy_pass ws://192.168.56.101:8123/api/websocket;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection “upgrade”;
}

location / {
proxy_pass http://192.168.56.101:8123/;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection “upgrade”;
}

Source: ServerAdmin jovan@ris.mk ServerName smkocani.duckdns.org DocumentRoot /var/www/html # Available loglevels: trace8, …, trace1, debug, info, notice, warn, # error, crit, alert, emerg. # It is also possible to configure the loglevel for

WebSockets on nginx was last modified: July 15th, 2024 by Jovan Stosic