Search found 23 matches

by JMG
Sat Feb 09, 2019 11:21 am
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 15908

Re: Extending the range of a Discone antenna down to 3.6 MHz

@glovisol
The discone itself NEVER will receice any reasonable signal at low frequencies! It is much to small compared to the wavelength.
by JMG
Fri Feb 08, 2019 12:55 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 15908

Re: Extending the range of a Discone antenna down to 3.6 MHz

Some time ago I did run some tests and simulations on the antenna at low frequencies. Here you find a comprehensive presentation of the basics. It may help to answer some of the questions. At my installation (l = 15m) the antenna gives good results up to a frequnecy of a wavelength of 4l=60m or f=5M...
by JMG
Thu Feb 07, 2019 11:44 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 15908

Re: Extending the range of a Discone antenna down to 3.6 MHz

Installing a common mode choke at the upper end of the antenna cable, the antenna will not work at low frequencies. At low frequencies the primary antenna element is the antenna cable. Installing the choke at the lower end results in a completely different antenna: it is a unsymmetrical dipole then,...
by JMG
Wed Feb 06, 2019 9:51 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 15908

Re: Extending the range of a Discone antenna down to 3.6 MHz

An excelent presentation of the fundamentals of the discone antenna, mounted on a pole, can be found here: https://www.youtube.com/watch?v=vFYVpJ9FPZ8 Please look at 12:20. Sory, it is in German. If you want to run some simulations: the total capacitance of the elements of the DJ-130 antenna is 25pF.
by JMG
Tue Feb 05, 2019 9:29 pm
Forum: SDR Antennas
Topic: Extending the range of a Discone antenna down to 3.6 MHz
Replies: 52
Views: 15908

Re: Extending the range of a Discone antenna down to 3.6 MHz

This has been reported many times before. It even works down below 10kHz. So, a well disgned installation will give you a frequency range of 10kHz to 2Ghz - at full sensitivity (SNR)! Background: at low frequencies the antenna cable (or the antenna pole) acts as a grounded vertical stub antenna. The...
by JMG
Fri May 11, 2018 8:03 am
Forum: SDRuno
Topic: Ver 1.22 Menus
Replies: 4
Views: 3154

Re: Ver 1.22 Menus

And how to store the new setting?
by JMG
Fri Nov 17, 2017 9:46 am
Forum: General
Topic: RSP RFI
Replies: 8
Views: 9207

Re: RSP RFI

Why have the modifications not been applied to the RSP1A?
Consequent grounding of the antenna- and the USB-port and/or internal decoupling result in a dramatic improvement in interference immunity.
by JMG
Wed Aug 09, 2017 8:25 am
Forum: SDRplay related
Topic: RSP2 & NDB RECEPTION
Replies: 6
Views: 4648

Re: RSP2 & NDB RECEPTION

You may take a look at the navy-signals at 20kHz. The narrowband signals (B=200Hz) have a world wide coverage. This will give you an idea on how good your antenna system is. And you can compare your signal to an excellent receiving system at the Netherlands: http://websdr.ewi.utwente.nl:8901/ At my ...
by JMG
Thu Jun 01, 2017 8:14 am
Forum: SDRuno
Topic: Antenna Referred Power Measurement.
Replies: 9
Views: 7272

Re: Antenna Referred Power Measurement.

"dBm" makes a lot of sense! DBm is a logarithmic parameter for rf-power, not depending on the impedance. In the near future it will replace all the last century parameters like dBuV, S-units, receiver sensitivity uV, power.... All modern test equipment like signal-generators, power sources...
by JMG
Wed Mar 22, 2017 10:49 pm
Forum: SDRplay related
Topic: SDRplay and SDR sharp
Replies: 11
Views: 13293

Re: SDRplay and SDR sharp

someYguy wrote:I just tried SDR# v1.0.0.1500(the latest) with the v2.2 plugin under Windows 7 and it works fine here.....


The latest version is 1530 now. Seems it does not work any more now.

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