Aeronetworks sro - Airborne Linux

A Formal Bow Tie Event I have made a few PCB antennas and the Yagis worked well, but they were very narrow band.  So I tried to improve that by making the elements conical - or in this case, since it is 2D PCB antenna, triangular. I think it is a fairly unique idea and I certainly haven't seen a picture of a PCB antenna like this before.  The Driven element and first director are flared to 3 mm (since there is no more space) and the Reflector and other Directors are flared to 10 mm. Wide Band Yagi with Unbalanced Co-ax Feed I'll see what happens once the conformal coating dried and I hooked up a cable. It is the same design I used before - I just flared the elements and left out the last 2 directors: This way I can compare the two antennas with each other.  I didn't bother to simulate it - I just went ahead and machined it to see what happens. Antenna Gain Initial tests showed that the gain is about 5 dBi which is typical for a 5 element Yagi and the bandwidth of the new ...

While playing with my milling machine and little microwave PCB Yagi antennas, I wondered about increasing the bandwidth and still getting directional gain.  A Log-Periodic antenna looks almost exactly, but not quite unlike a Yagi... Practice is the best of all instructors -- Publius Syrus On a Log-Periodic, all the elements are driven, but each dipole is reversed by 180 degrees.  To make it on a single sided PCB, will require some links to wire up the dipoles.  I added a BNC connector and thin equilength coax to the feed points of the antennas. Stacked Log-Periodic 5GHz To reduce the amount of copper that needs to be milled out, I cut the board close to the radiators.  The bar at the back is for mounting and also serves as a reflective ground plane.  A log-periodic antenna is surprisingly compact and a little 5 dipole antenna will have a gain of about 3 dBi.   By carefully stacking two of them 0.75 Lambda1 centre to centre (54 mm), one should g...

When you need to test two radios in a lab, they are awfully close together and may not work over the air, since the transmitter will overdrive and saturate the receiver.  You may even damage the receiver since the radio front end is very sensitive and the transistor features are extremely small.  If you would accidentally touch the antennas of two radios together, you could instantly melt the receiver front end. DIY 90 dB(?) Attenuator To avoid this melt-down problem, military manpack radios are usually built with power transistors on the front end - the same ones used in the power amplifier.  Since power transistors are expensive, commercial radios are usually not so rugged. Path Loss If your transmitter operates at +30 dBm (1 Watt) and the receiver has a sensitivity of -90 dBm (1 nano Watt), then to work properly, you need a path loss of 80 to 90 dB, to bring the transmit signal down to a safe level of about -60 dBm. You can then hook the two radios back t...

I've been toying with a switched phased array antenna design for use on a small aircraft.  This type of antenna could be made to radiate forward, backward, or to the sides.  With the addition of a Raspberry Pi Zero (or Arduino Teensie https://www.aeronetworks.ca/2016/08/minimalist-arduino-gps-parser.html ), a UBlox GPS receiver and 4 little RF switches, your toy aircraft could then always point its antenna towards your ground control system, without using any step motors or moving parts - well, except for the armatures of the little RF switches. Phased Array NEC2 Simulation The design is essentially four Yagi antennas positioned back to back in a cross.  Only one dipole is driven at any time and the result is that the rearward parasitic elements act as a reflector for the antenna that is active.  This improves the front to back ratio quite noticeably.  The NEC2 graphs show extremely small back and side lobes, which I found so encouraging, that I went ahe...

I like tinkering with wire antenna designs, since they are simple and cheap to make.  Mr Yagi invented his antenna about 100 years ago, but there are still some things left to learn about it. 900 MHz ISM Band Yagi The 900 MHz ISM band ranges from 902 to 928 MHz.  Covering the whole band with a single Yagi antenna is difficult, since they are inherently narrow band devices.  Consequently some tweaking is required and the result below is a desensitized design that can be built and replicated quite easily, but you need a network analyzer - "To Measure, is to Know!" A Yagi generally consists of a Reflector, Radiator and one or more Director elements, arranged on a boom.  For a small Yagi, a wooden ruler works a treat, since one can easily mark the position of the wires.  The wire elements are fastened to the bottom of the ruler with hot glue.  The wire elements are  made from straightened out jumbo size paper clips.  The balun, is tw...