Search found 180 matches

by snn47
Sat Aug 31, 2019 1:36 pm
Forum: Antennas
Topic: Antenna Element Wire Gauge Effect
Replies: 4
Views: 1464

Re: Antenna Element Wire Gauge Effect

which frequency range, how high AGL and how long (inm) is long for you?
Why .would you want to connect a wire to your PC?
by snn47
Mon Aug 26, 2019 6:26 pm
Forum: RTL-SDR Discussion
Topic: Showing wave form on an oscilloscope.
Replies: 5
Views: 1822

Re: Showing wave form on an oscilloscope.

Even If your oscilloscope is fast enough to display strong signals at 137 MHz, oscilloscope are quite insensitive compared to the frontend in spectrum analyzer. The easy solution would be to use a receiver with sufficient bandwidth and sensitivity and connect an IF-output to your oscilloscope.
by snn47
Sun Aug 25, 2019 6:48 pm
Forum: Antennas
Topic: Adjustable Matching Transformer Exist ??
Replies: 4
Views: 1430

Re: Adjustable Matching Transformer Exist ??

antenna tuner also can be used as pre-selector tunable bandbass filter
It depends on the design of the matching network if it can be used as pre-selector tunable bandbass filter, e.g a Pi-design is a Low pass filter.
by snn47
Sat Aug 24, 2019 7:07 pm
Forum: Antennas
Topic: Adjustable Matching Transformer Exist ??
Replies: 4
Views: 1430

Re: Adjustable Matching Transformer Exist ??

Yes impedance matching circuit/transformer exist. The problem is you have to place such a device directly between the antenna and the transmission line e.g. coax cable to work. Then you have to tune it to the frequency you want to operate on, and again after you change the frequency. This requires s...
by snn47
Sat Aug 24, 2019 6:53 pm
Forum: Antennas
Topic: antenna related information and guidance for asking questions to improve chances for an answer
Replies: 6
Views: 2443

Re: guidance for asking antenna related questions improves chances for an answer -proposal for a sticky post

@ High SNR
Added your suggestions

@hotpaw and others
Are you proposing to add this information here or as separate post, e.g. Must read on antenna and transmission lines?
by snn47
Sat Aug 24, 2019 10:00 am
Forum: User Projects
Topic: USB HUB Recommendation!!!
Replies: 1
Views: 1466

Re: USB HUB Recommendation!!!

Even if an USB Hubs is shielded it won't help if you use poorly shielded USB cableand if you don't have a consistant shielding from connector to cable to connector, for all devises connected together. In comercial receiver metall boxes are used, which are either soldered cover or have additional con...
by snn47
Sat Aug 24, 2019 9:41 am
Forum: Antennas
Topic: antenna related information and guidance for asking questions to improve chances for an answer
Replies: 6
Views: 2443

antenna related information and guidance for asking questions to improve chances for an answer

Rev.2 2019.Oct.09 Rev.1 2019.Aug.24 I propose to make a sticky post that provides guidance about how to formulate antenna related questions. This makes it easier to no what information is needed, without having to consult a crystal ball if you are lucky enough to have a funtional one. This makes it...
by snn47
Sat Aug 10, 2019 7:47 pm
Forum: RTL-SDR Discussion
Topic: Filters, isolators, bias
Replies: 8
Views: 1673

antennas with limited bandwidth, HP- LP-,BP,BR- Filters, vs. isolators or bias

It depends on the frequency range you want to receive and your RF enrionment, what is the best (affordable) option to reduce interference or in most cases it is overloading of the receiver. Interference are signals or spurious emmisssions that fall within the receiver RF bandwidth. Since RTL-SDR do ...
by snn47
Sat Aug 10, 2019 7:29 pm
Forum: Antennas
Topic: Antenna for encrypted scanner frequencies
Replies: 5
Views: 1804

Re: Antenna for encrypted scanner frequencies

For your understanding: Antenna are passive they don't care about what signals are transmitted or received by the it. It's Transmitter and Receiver that provide en-/decoding of signals. a) its illegal b) there is a reason for why its encrypt c) depending on laws of the country you try to receive suc...
by snn47
Sat Aug 10, 2019 7:23 pm
Forum: Antennas
Topic: Folded dipoles and quad loops with SDRs
Replies: 6
Views: 2054

Re: Folded dipoles and quad loops with SDRs

Those antenna types do not necessarily create a short for the DC path, but It depends on how the antenna is matched to the transmission. But mostly they do, but you can also add a a DC isolation via e.g. a HP-filter.