Re: LF: Re: U.S. VLF License WH2XBA

["Alan Melia" <alan.melia@btinternet.com>]

Hi Warren I think the 70kHz "boundary" is just the point at which the Earth-Ionosphere waveguide supports so many different modes that the modelling becomes difficult and the ray path is as effective.  Even this transition is fuzzy and is often quoted as low as 50kHz.

 

It may be of interest that Paul Nicholson has put a web front end to the LWPC propagation code

http://abelian.org/lwpc/  This gives reasonable results up to around 45kHz. I have done some tests on it and it gives quite sensible answers.

 

Alan

G3NYK

----- Original Message -----

From: Warren Ziegler

To: rsgb_lf_group

Sent: Saturday, March 01, 2014 3:54 PM

Subject: Re: LF: Re: U.S. VLF License WH2XBA

Hi Alan,

      I agree, there was nothing that I could find that indicated that there would be a problem at 30kHz. I even checked with a well known vlf expert who has done design work for some of the BIG military vlf systems. Somewhere around 70kHz there is a transitional area between waveguide modes applicable at vlf and ray-tracing which is applicable at higher frequencies. The increased number of modes above 70kHz I believe explains the deep fading there as the modes constructively and destructively interfere.

   However, it didn't hurt to ask for the additional frequencies as Dex was able to use an existing loading coil to get on 45kHz within hours of the license being issued!

73 Warren K2ORS

On Sat, Mar 1, 2014 at 10:40 AM, Alan Melia <alan.melia@btinternet.com> wrote:

Hi Warren I cant see30kHz being particularly different for propgation in that part of the spectrum. I can see 2nd harmonic trashing WWVB clock synchronisation over a substantial area though, bearing in mind the receivers are very simple.........and most only try to sync around midnight.

 

Alan

G3NYK.

----- Original Message -----

From: Warren Ziegler

To: rsgb_lf_group

Sent: Saturday, March 01, 2014 3:17 PM

Subject: LF: U.S. VLF License WH2XBA

Hello the list,

    Several questions have come up concerning the WH2XBA grant and I thought I might address them here.  Bob W2ZM contacted me about applying for a grant at the top end of the vlf range (just below 30kHz).

The thought was that the high end of vlf would be a bit less challenging than the low end below 9kHz (which is unregulated).

    Some of the usual suspects expressed interest so they were added to the application. Also Jim AA5BW - Jim and I have a mutual friend through work - Jim is highly capable and  technical and has multiple sites throughout the country.   There was some concern that the frequencies around 30kHz were unoccupied due to propagation reasons and some thought it might be good to go a bit higher, hence the 27-59kHz range, leaving clearance for WWVB at the top end. 

     The license is for 5W ERP, 27-59kHz, CW and every data mode that I could think of.

    The application was filed on January 29 and the license issued on February 27 - this was despite some Federal Holidays and closings due to blizzards!  So I suspect that it didn't raise too many questions.

     The stations are:

WH2XBA/1     Bob W2ZM

WH2XBA/2   Warren K2ORS

WH2XBA/3     Jay W1VD

WH2XBA/4     Dex  W4DEX

WH2XBA/5   Laurence KL1L 

WH2XBA/6 /7 /8 etc etc James Plesa AA5BW

 

WH2XBA Grant Attached.

73 Warren K2ORS

--
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

                WG2XRS/1

                WH2XBA/2

 

--
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1