Search found 33 matches

by HighSNR
Fri Apr 26, 2019 7:50 pm
Forum: Antennas
Topic: Antenna tuning, impedance matching, baluns, common mode currents, my head exploding...
Replies: 6
Views: 517

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...
by HighSNR
Sun Apr 14, 2019 2:13 pm
Forum: Antennas
Topic: Another Double Cross Antenna build (went wrong)
Replies: 15
Views: 1272

Re: Another Double Cross Antenna build (went wrong)

Its rare for a satellite to actually be directly overhead. Most commonly they will acutally be at a lower elevation. The Lindenblad (double cross) is designed to give circular polarisation as a replacement for a linear dipole. For coverage at 90degree elevation you can use a turnstyle(crossed dipole...
by HighSNR
Sun Apr 14, 2019 1:33 pm
Forum: Antennas
Topic: Another Double Cross Antenna build (went wrong)
Replies: 15
Views: 1272

Re: Another Double Cross Antenna build (went wrong)

I would expect this antenna to have a null directly above and below.

https://www.amsat.org/articles/w6shp/lindy.html
by HighSNR
Sat Apr 13, 2019 7:53 am
Forum: Antennas
Topic: What antenna is this
Replies: 1
Views: 281

Re: What antenna is this

We can't see the actual antenna, but it's probably an L-Band circular patch antenna. The 'directional coupler on the back is actually a 90 degree hybrid used to feed the antenna and provide the circular polarisation.
by HighSNR
Thu Apr 11, 2019 5:45 am
Forum: Other SDR Devices
Topic: List of HF SDR Transceivers
Replies: 5
Views: 527

Re: List of HF SDR Transceivers

Thanks for the info on that. I will definately look into openHPSDR and its derivatives.
by HighSNR
Wed Apr 10, 2019 9:33 pm
Forum: Other SDR Devices
Topic: List of HF SDR Transceivers
Replies: 5
Views: 527

Re: List of HF SDR Transceivers

It was an experimentation radio I was looking for. Something that works with GNU radio and has a bit more dynamic range than the HackRF for instance.
by HighSNR
Sat Apr 06, 2019 6:17 am
Forum: Other SDR Devices
Topic: List of HF SDR Transceivers
Replies: 5
Views: 527

List of HF SDR Transceivers

Im looking for options for an SDR based Transceivers for HF. It seems like there is a shortage of options. Hopefully the RTL community can help me compile a list and perhaps give me some feedback as to how well they work at HF? Are there other radios that can be modified to work well at HF? So far I...
by HighSNR
Mon Jan 14, 2019 6:54 am
Forum: Other SDR Devices
Topic: Nonlinear junction detector
Replies: 4
Views: 13590

Re: Nonlinear junction detector

I think you would need full duplex unless you have a seperate signal source.
by HighSNR
Sun Dec 09, 2018 2:00 pm
Forum: Antennas
Topic: 1090 Antenna real or Fake?
Replies: 6
Views: 15245

Re: 1090 Antenna real or Fake?

There is no way to tell without some sort of measurement. Many antennas I get from reputable brand name suppliers dont come close to meeting their performance specs.
by HighSNR
Fri Nov 23, 2018 8:09 pm
Forum: Antennas
Topic: New Spiral Antenna
Replies: 0
Views: 12911

New Spiral Antenna

https://hexandflex.files.wordpress.com/2018/11/big-and-little.jpg?w=300 Hi all, Hopefully Rtlsdr wont mind me posting here with an antenna i'm selling on Tindie. In mitigation I have tried hard to provide really good documentation on how it was designed and the decisions that went into it. Hopefull...