Radio Frequency (RF) & Wireless Design

All ;

Just wanted to share with you someone else's project and how they approached an Amplified Antenna Project. This GNSS / GPS Antenna uses a Low Noise Amplifier (LNA) right on the antenna to get the best possible Signal-to-Noise (S/N) for reception. The LNA gives an output gain of over 18 dBi ( > 63x ) and can be made with basic materials and tools.

https://hackaday.io/project/176769-active-gnss-antenna

In the article it explains that he is using a mini-VNA that are very popular on ebay and amazon. The VNA shows the frequency response for the antenna as well as the impedance of the antenna. His initial reading for the antenna is 95+j2 showing 95 ohms DC plus a small amount of inductive reactance at 2 ohms.

The matching network will match the antenna impedance of 95 ohms to the (typical) to the LNA which is 50 ohms which is already matched to the coaxial connector impedance of 50 ohms. The matching network also provides a form of BalUn between the 'balanced' antenna elements to the 'unbalanced' coaxial cable.

There are (2) additional input and output Band Pass Filters (BPF) that are used to filter out unwanted noise and narrow the frequency band to a single narrow frequency channel.

The antenna elements are curved into a spiral and created a 'circular' polarization which is necessary since the orientation of the rocket will be unknown in flight. This provides a uniform signal response such that any direction is receivable.

I will try to model this antenna and follow the progress of antenna.

Please be sure to join, mention this thread and project to others, and comment below !