DIY - 900MHz Microstrip Filter (Bandpass)

Latest update time：2021-09-01 03:35

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DIY

I have been very busy recently. A few days ago, a teacher from a school asked me to make a 900MHz microstrip filter. Below is my design process and actual test, and I would like to share it with you...
I used the powerful ADS software to simulate, then made the PCB, and then debugged and tested it.
Considering the volume of the 900MHz filter, I did not use the parallel coupled line method, because that method is relatively long, and I chose a hairpin structure.

After designing the structure, the next step is to optimize the parameters. This can be used to determine the final parameters. The simulation diagram is as follows.

This picture is the result of debugging after layout simulation. That is to say, the schematic simulation is good, but the corresponding layout simulation has some deviations, so I then adjust the schematic, optimize, and finally determine the size. After the size is determined, generate the layout.
The next step is the layout simulation. This design uses the common FR4 board, which is also the cheapest, but the actual loss is relatively large.
The following is the actual PCB and test results.
Physical
This test is for standing wave, SWR 1.2 @ 900MHz
Test Panorama
The bandwidth and loss of the test are only about 50 MHz, which is quite narrow. The main reason is that the loss is relatively large, which is also directly related to the board material.