NJDTechnologies

Radio: it's not just a hobby, it's a way of life

Current Operating Frequency and Mode

OFF AIR but QRV after dark tonigth

SCHEDULED ACTIVITY: CQ 474.5 kHz CW by 1015z through sunrise most days, WX permitting

Higher noise than previous session but trans-Pacific and trans-Atlantic activity continues

– Posted in: 630 Meter Daily Reports, 630 Meters

It was noisier than the previous session but the band was very active as WSPR dominated the session with 82 MF WSPR stations observed at 0330z.  Geomagnetic conditions were very calm, however, Solarham reports that we should already be observing storm levels.  Solar wind is currently elevated above 400 km/s but conditions remain quiet for the moment.  The DST often increases before storming levels begin to present and we have seen that behavior through this session.

planetary-k-index 040216

 

Kyoto DST 040216

 

Australia 040216

 

Dave, G4FRE, reports his first trans-Atlantic report of 2016 at his station, receiving WG2XJM during the session.  He reports that he was using an Elecraft K3S and PA0RDT E-probe.  Dave provided the following picture of his path to North America, which happens to have a hill “in the way”:

G4FRE 040216

G4FRE path to WG2XJM

 

Neil, W0YSE/7 / WH2XGP, reports good band conditions, decoding eight WSPR stations and being decoded by twelve, as he continues to operate at 200 mW ERP.

WG2XSV 040216

 

Mike, WA3TTS, provided the following report and statistics from his station near Pittsburgh:

WA3TTS 040216

 

Ken, K5DNL / WG2XXM, reports that he decoded eight unique WSPR stations and was decoded by forty WSPR stations including VK4YB.

WG2XXM VK4YB 040216

WG2XXM, as reported by VK4YB

 

Larry, W7IUV / WH2XGP, reports that he decoded ten unique WSPR stations and was decoded by 38 WSPR stations including VK4YB.

WH2XGP VK4YB 040216

WH2XGP, as reported by VK4YB

 

Phil, VE3CIQ, reports that he decoded six unique WSPR stations and was decoded by 16 WSPR stations including two-way reports with WH2XGP.

Steve, VE7SL, reports that he decoded twelve WSPR stations including WI2XFI and “the rare VE3CIQ” in the East.

Regional and continental WSPR breakdowns follow:

NA 040216

North American 24-hour WSPR activity

 

EU 040216

European 24-hour WSPR activity

 

VK 040216

Australian 24-hour WSPR activity

 

JA 040216

Japanese 24-hour WSPR activity

 

There were no reports from the trans-African path.  UA0SNV was present from Asiatic Russia but no reports were found for Vasily in the WSPRnet database.

Eric, NO3M / WG2XJM, experienced a good session of trans-Atlantic reports from a number of stations and Stefan, DK7FC was reported by WD2XSH/17.

WG2XJM PA0RDT 040216

WG2XJM, as reported by PA0RDT

 

WG2XJM M0LMH 040216

WG2XJM, as reported by M0LMH

 

WG2XJM G3XKR 040216

WG2XJM, as reported by G3XKR

 

WG2XJM G4FRE 040216

WG2XJM, as reported by G4FRE

 

DK7FC WD2XSH17 040216

DK7FC, as reported by WD2XSH/17

 

In the Caribbean, Roger, ZF1RC, reported four North American stations during the session. Eden, ZF1EJ, reported three stations on 630-meters but due to a data problem, the map is not included.

ZF1RC 040216

ZF1RC 24-hour WSPR activity

 

In Alaska, Laurence, KL7L / WE2XPQ,  was reported along the West coast of North America as well as Hawaii.  KL7L was designated as receive-only and reported stations in the Pacific Northwest and Hawaii.

WE2XPQ 040216

WE2XPQ 24-hour WSPR activity

 

KL7L 040216

KL7L 24-hour WSPR activity

 

 

WE2XPQ WH2XCR 040216

WE2XPQ, as reported by WH2XCR

 

In Hawaii, Merv, K9FD/KH6 / WH2XCR, continues to experience distant two-way report with VK4YB and WG2XJM.  The Japanese path continues to be cut off.

WH2XCR 040216

WH2XCR 24-hour WSPR activity

 

WH2XCR VK2XGJ 040216

WH2XCR, as reported by VK2XGJ

 

WH2XCR VK4YB 040216

WH2XCR, as reported by VK4YB

 

WH2XCR KL7L 040216

WH2XCR, as reported by KL7L

 

In Australia, Phil, VK3ELV, and Roger, VK4YB, received reports from WH2XCR.  Phil, received additional reports from three JA stations, with 7L1RLL_4 and TNUKJPM reports coming from late in the previous session.

VK4YB WH2XCR 040216

VK4YB, as reported by WH2XCR

 

VK3ELV WH2XCR 040216

VK3ELV, as reported by WH2XCR

 

VK3ELV TNUKJPM 040216

VK3ELV, as reported by TNUKJPM

 

VK3ELV JH3XCU 040216

VK3ELV, as reported by JH3XCU

 

VK3ELV 7L1RLL_4 040216

VK3ELV, as reported by 7L1RLL_4

 

Jim, W5EST, provided this technical discussion entitled, “MF/LF ANTENNA DEGREE-AMPERES”:

“Have you ever wondered what antenna degree-amperes are for? Here’s my take.

RF current along the length of a vertical generates the oscillating magnetic field to launch your RF signal. Degree-amperes numerically express a quantity that when squared (degree-amps)2 relates to total radiated power TRP. The idea is to multiply an average value of RF current (as if it were uniform over the whole vertical antenna height) times the electrical length in degrees of the vertical height of the antenna system. More height and more average current jointly make more TRP.  A quarter-wave vertical would stand roughly 90° tall.  Degree-amps capsulize an area-under-the-curve of nonuniform current distribution along vertical height.

But on 630m, verticals are electrically short. A vertical 20m tall occupies 11.4° on the 630m band. Most Part 5 and non-USA ham 630m verticals are electrically 5° to 10° tall. On 2200m the same verticals are 1.5° to 3° tall.  If you run 1.5A RF averaged over height, that’s 7.5-15 degree-amps on 630m and 2.25-4.5 degree-amps on 2200m.

Using electrical degrees instead of multiplying by the length itself recognizes that the same vertical height of antenna, when driven with the same RF current, radiates less TRP at lower frequencies, longer wavelengths.  If you read somewhere about ampere-radians, just remember that 1 radian = 57.3° and it’s the same thing in concept as degree-amperes.

Field strength as measured by field strength meters is directly proportional to degree-amperes. The next web site says 1 degree-amp gives 1.04 mV/meter at 1 kilometer.  Nice! http://www.vias.org/radioanteng/radio_antenna_engineering_01_06_01.html , citing E. Laport.

I hope to talk more about RF field strength in a blogpost some future day. In the meantime, let’s get better acquainted with degree-amperes today and critique top hats tomorrow.

A vertical without a top hat has no current at its tip, meaning most of the upper part of a hatless short vertical is inefficiently used.  Average RF current along the hatless vertical’s height becomes half what the RF ammeter shows.  If there were current at the hatless tip, the antenna would be undesirably sparking and going nonlinear!

Talking about RF base current and estimated radiation resistance Rradiation just gives you an different way of picturing the same thing as degree-amperes. You may see a radiation resistance formula that’s proportional to the square of the fraction that the antenna vertical height bears to the wavelength.  Rradiation = a2 (h/λ)2.   The fudge factor a2 depends on the amount of top hat and gets you to ohms.  On the above web site you you see a log-log graph to straighten out the squared quantity (h/λ)2 . It includes various graphical straight lines for different top hats–different values of the constant a.

The antenna design jargon of degree-amps and radiation resistance Rradiation flow from one same idea—power equals I2R.  Total radiated power is TRP:

TRP = Ibase2 Rradiation.

The degree-amps approach recognizes that the fudge vector a2 depends on the amount of top hat because that affects the RF current distribution:

        TRP = Ibase2 Rradiation = Ibase2 a2 (h/λ)2

When you massage the equation you see that constant a takes you from antenna base RF current to the average current along the whole vertical height of the antenna system. What’s inside the brackets is proportional to degree-amperes.

        TRP = [a Ibase h/λ]2

TRP is proportional to the square of field strength at 1 kilometer, and field strength itself is proportional to degree-amperes. One could get really technical about the math, but this is enough for now.  Remember that EIRP is triple the TRP of a short vertical!

For more background on the subject of degree-amps see your favorite antenna textbook, or see pp. 16-7 and 16-8 in this additional web site: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwjks977u-vLAhXIMyYKHcy1C5sQFggiMAE&url=http%3A%2F%2Fwww.qrz.ru%2Fschemes%2Fcontribute%2Farrl%2Fchap16.pdf&usg=AFQjCNEBblgaRaN6sca4IbD9xc9IqB8Mcw  “

 

Additions, corrections, clarifications, etc?  Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!