LOW PASS FILTER FOR OPTIMUM LOW FREQUENCY RECEPTION

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glovisol
Posts: 390
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: LOW PASS FILTER FOR OPTIMUM LOW FREQUENCY RECEPTION

Postby glovisol » Wed Feb 13, 2019 5:05 pm

MEDIUM WAVE REJECTION WITH A CAUER C 05 15 40 PASSIVE LOW PASS FILTER

Network Analyser measurements

The two enclosed PC screens show the SWR performance of the LF Low Pass filter in the operating range.

- In the 560-1000 screen the AA-30 Network Analyser is connected to the antenna input and shows the SWR with the filter terminated or not terminated with a 1 KOhm resistor, simulating the load of the RSP balanced HI Z input.

- in the 1000-560 screen the network Analyser is connected to the 1 Kohm port while the antenna input is terminated with a 560 Ohm resistor. This screen also compares this reverse SWR with the forward SWR of the previous screen.

In the two screens the worsening of the SWR at low frequency is due: (a) to the proximity of the measurement limit of the AA-30 and (b) to the natural low frequency roloff of the ferrite isolation transfomer. These measurements underline the excellent performance of this filter.
Attachments
LOW PASS SWR 560-1000.jpg
LOW PASS SWR 560-1000.jpg (127.5 KiB) Viewed 374 times
LOW PASS SWR 1000-560.jpg
LOW PASS SWR 1000-560.jpg (124.65 KiB) Viewed 374 times

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