Search found 42 matches

by HighSNR
Sat Aug 24, 2019 9:55 am
Forum: Antennas
Topic: guidance for asking antenna questions improves chances for an answer -proposal for a sticky post
Replies: 1
Views: 8

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

All seem reasonable to me. I'm sure there lots of other info people could volunteer too. Just telling us the frequency ( in Hz) is a big help. Don't make us research that esoteric signal that may even be specific to your country. Cable lengths and types used is also worth knowing. What type(RG numbe...
by HighSNR
Tue Aug 20, 2019 8:49 pm
Forum: Antennas
Topic: Boxx Antenna?
Replies: 4
Views: 174

Re: Boxx Antenna?

It's not immediately obvious. Probably the two outer arms are connected together and the middle is the driven connected together the centre of the feed. It look alike the lid is removable, can you take some internal photos, or measure the resistance between each antenna arm and the centre and out co...
by HighSNR
Sun Aug 11, 2019 8:19 am
Forum: Other SDR Devices
Topic: Any good full-duplex SDRs?
Replies: 8
Views: 598

Re: Any good full-duplex SDRs?

BladeRF micro 2.0 is very easy to get locked coherent Tx and Rx.

I guess that Pluto SDR might be ok as well, but I can't confirm this.
by HighSNR
Sat Aug 10, 2019 11:35 am
Forum: Antennas
Topic: Signal Splitting?
Replies: 10
Views: 338

Re: Signal Splitting?

Considering a 2 way splitter firstly. When you split a signal, the best case is that half the power goes to each output. That's a 3dB reduction. An important characteristic of splitters is maintaining the characteristic impedance of the transmission line (normally 50ohms). To achieve this of the the...
by HighSNR
Mon Jul 22, 2019 8:51 pm
Forum: Antennas
Topic: Dual V-Dipole
Replies: 2
Views: 535

Re: Dual V-Dipole

I would love to help, but it's difficult with the information provided. I don't personally have any experience with the NOAA or Meteor systems, so it's hard to make recommendations. The reason it only works in one direction could be due to interference coming from the direction of interest. It sound...
by HighSNR
Tue Jun 18, 2019 2:40 am
Forum: Antennas
Topic: Strangest thing with my antenna!
Replies: 4
Views: 1431

Re: Strangest thing with my antenna!

That sounds like the most likely scenario. As admin says, the yagi is unidirectional, but it is also tuned to the TV frequencies and may not perform well outside this band. Additionally the amplifier may also contain a filter to reject out of band signals. Some amplifiers have a second input for an ...
by HighSNR
Mon Jun 10, 2019 4:34 am
Forum: Antennas
Topic: Holiday antenna
Replies: 10
Views: 1255

Re: Holiday antenna

I use that: https://www.tindie.com/products/hagster/ultra-wideband-vivaldi-antenna-800mhz-to-6ghz/ The problem is the are a little bit brittle. The actual antenna is fairly strong and I have yet to break one, but it is possible to damage the connector, especially if attaching heavy coax. If you hav...
by HighSNR
Sun Jun 09, 2019 5:37 pm
Forum: Antennas
Topic: Holiday antenna
Replies: 10
Views: 1255

Re: Holiday antenna

I can recomend my spiral antennas for covering 300MHz upward. They also seem to work fairly well from 90 to 200Mhz, but no use at all at HF.

https://www.tindie.com/products/15447/
by HighSNR
Sun Jun 09, 2019 9:58 am
Forum: Antennas
Topic: Holiday antenna
Replies: 10
Views: 1255

Re: Holiday antenna

I have never heard of anyone getting arrested in Europe for scanning. Rules are probably different for different countries in the EU, but so long as you are not demodulating and intercepting comms where people would have an expectation of privacy, you are probably ok. The old classic was listening t...
by HighSNR
Fri Apr 26, 2019 7:50 pm
Forum: Antennas
Topic: Antenna tuning, impedance matching, baluns, common mode currents, my head exploding...
Replies: 7
Views: 1563

Re: Antenna tuning, impedance matching, baluns, common mode currents, my head exploding...

The impedance should be approximately real as the length has been tuned to make it resonant(XC = XL). If possible it is always better to tune an antenna this way rather than rely on a matching network of L's and C's to shit it round the smith chart. Sometimes (particularly with small antenna) this i...