HFU HF Underground
Loggings => DGPS => Topic started by: Uli_Bel on February 28, 2018, 1224 UTC
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In the past, I found that my very large EWE performed excellent towards Northwest, decoding a lot of North-American beacons.
However very soon, I need to dismantle the temporary installations (large EWE, Beverages), as they are erected over agricultural farmland, which will be needed soon to prepare for the next summer season.
I mentioned, that I want to check, how small you can make EWE antennas to still work efficiently on 300kHz. I have now installed a quick test antenna, really really small : 2.5m up, 5m horizontal, 2.5m down to resistor 700Ohm, total instead of 100m wire of the big EWE, only 10m of wire- unfortunately to make it quickly happen, it is NOT pointed to NW (over the atlantic ocean) but to Scandinavia (Northeast).
So far, I did not fine-tune the resistor value - it seems to me, that tuning is necessary, as I can see a lot of southwest Europe - look at the many decodes of Cape Ferret (which is also 'dubbed' as the Brazilian beacon as false decodes). I will try to increase the Front/Back ratio in the future.
A lot of Scandinavia was indeed heard - however the UK, was very weak, although the distance to many of the beacons in Scandinavia is larger than to the UK - this is certainly due to the directivity of the little EWE out of only 10m wire...
I must mention, that a high impedance pre-amp is used to feed the EWE - instead of the impedance matching transformer, I directly connected the pre-amp to pick up the voltage between the wire an a ground rod (1m of copper-pipe, only half inch thickness (gasinstallation material) for quick solution)
So - do not expect a lot of North-America.... wrong direction for this test antenna.
My feeling so far is, that it is really the minimum size, which will work - but only with pre-amp.
I will be better to at least double the size - make an inv. U (EWE style) out of 20m wire, instead of only 10m
Regards,
Ulli, ON5KQ
Here are the logs from late evening (22h utc) tot early morning around local sunrise:
Count ID ref1 ref2 kHz Baud City Country Lat Lon km Deg
2 001 001 001 297,5 200 San Carlos Centro Argentina -31,967 -60,925 11.136 231
2631 269 466 466 310,0 100 Cabo de Santa Marta Grande Lt BBrazil -28,606 -48,824 10.195 224
5 626 652 653 310,5 200 Bachu Jiao Lt China 20,004 110,944 9.472 64
4 614 628 629 295,0 200 Shitang China 28,267 121,617 9.358 51
28913 652 704 705 302,0 200 Ose Saki Japan 32,622 128,614 9.311 44
2 925 320 321 313,0 200 Moise, QC Canada 50,202 -66,119 4.717 297
4 940 338 339 315,0 200 Cape Race, NL Canada 46,661 -53,075 4.052 286
3 944 342 343 310,0 200 Cape Norman, NL Canada 51,509 -55,831 4.004 295
25 342 484 485 308,0 200 Horta Azores 38,533 -28,617 2.830 254
865 405 605 001 314,5 100 Marjaniemi Finland 65,033 24,567 2.005 30
109 005 005 005 311,0 100 Shepelevskiy 2 Russia [Eu] 59,983 29,15 1.913 48
4 513 793 823 286,5 200 Skomvaer Lt, Rost Norway 67,419 11,883 1.911 11
54 408 608 001 290,5 100 Kokkola Finland 63,833 23,167 1.866 31
62 461 722 722 311,5 100 Bjuroklubb Sweden 64,491 21,587 1.861 28
12412 406 606 001 287,0 100 Klamila Finland 60,5 27,433 1.848 45
2833 531 841 001 295,5 100 Narva Estonia 59,467 28,04 1.835 49
8969 407 607 001 292,5 100 Haarajoki Finland 60,517 25,167 1.738 43
679 462 724 001 289,0 100 Jarnas Sweden 63,486 19,655 1.716 28
8356 400 600 001 293,5 100 Porkkala Pilot Station Finland 59,981 24,403 1.673 44
2865 401 601 001 287,5 100 Mantyluoto Finland 61,599 21,475 1.640 36
1649 340 480 481 311,5 200 Cabo Carvoeiro Lt Portugal 39,365 -9,411 1.606 223
10537 404 604 001 301,5 100 Turku Finland 60,442 22,224 1.596 40
7252 530 840 840 307,0 100 Ristna Lt Estonia 58,945 22,058 1.501 46
7483 464 728 728 307,5 100 Kapellskar Lt Sweden 59,719 19,087 1.408 39
6954 463 726 001 299,5 100 Skutskar Sweden 60,617 17,433 1.405 33
3599 454 715 716 287,5 100 Torshavn Faroes 62,023 -6,841 1.390 338
12967 468 734 734 298,0 100 Nynashamn Sweden 58,946 17,958 1.305 40
1542 361 522 001 294,5 100 Cala Figuera Balearics 39,465 2,528 1.260 183
1034 363 526 001 286,0 100 Castellon Spain 39,967 0,017 1.228 193
2 362 524 525 293,0 100 Mahon, Menorca Balearics 39,867 4,3 1.217 176
7231 465 730 001 297,5 100 Hoburg Sweden 56,928 18,156 1.191 49
7947 470 738 001 288,5 100 Otterbaecken Sweden 58,867 14,1 1.135 33
31 364 528 001 291,0 100 Cabo Salou Spain 41,05 1,167 1.094 189
5 467 733 001 302,0 100 Hjortens Udde Sweden 58,633 12,667 1.062 31
4639 444 684 694 295,5 100 Butt of Lewis Lt Scotland 58,526 -6,27 1.052 329
12655 445 685 695 291,5 100 Sumburgh Shetland Isles 59,869 -1,276 1.048 346
12595 460 720 001 292,0 100 Holmsjoe Sweden 56,433 15,65 1.032 48
54151 500 780 810 310,5 200 Faerder Lt Norway 59,034 10,533 1.029 24
5912 351 502 001 289,0 100 Cabo Mayor Spain 43,4 -4,417 1.002 218
567 366 532 532 313,5 100 Cabo San Sebastian Spain 41,883 3,2 990 180
12951 469 736 001 296,5 100 Goteborg Sweden 57,617 11,967 948 33
11869 451 700 701 289,5 100 Hammerodde Lt, Bornholm Denmark 55,31 14,779 922 52
1998 435 670 671 288,5 100 Tory Island Lt Ireland 55,267 -8,25 912 308
10625 453 710 711 296,0 100 Skagen West Lt Denmark 57,761 10,605 912 29
290 466 732 001 293,0 100 Kullen High Lt Sweden 56,303 12,46 865 41
9123 503 783 813 304,0 200 Lista Lt Norway 58,116 6,572 844 14
14268 001 850 851 295,0 100 Obristvi Czech Republic 50,301 14,484 799 89
9595 446 686 696 297,0 100 Girdle Ness Lt Scotland 57,142 -2,056 785 336
12195 491 761 721 308,0 100 Gross Mohrdorf Germany 54,367 12,917 767 55
2632 336 466 466 310,0 100 Cap Ferret France 44,567 -1,25 767 207
11001 443 693 001 285,5 100 Stirling [Earls Hill] Scotland 56,067 -4,067 758 324
8900 496 766 766 313,5 100 Mauken Germany 51,717 12,817 677 77
7399 495 765 765 314,5 100 Bad Abbach Germany 48,933 12,033 666 105
2208 452 705 706 290,0 100 Blavandshuk Lt Denmark 55,564 8,085 623 30
6635 441 681 691 306,0 100 Lizard Lt England 49,966 -5,202 602 265
126 334 464 464 307,0 100 Les Sables Olonne France 46,517 -1,8 600 220
591 332 462 462 308,5 100 Pont de Buis France 48,3 -4,083 593 245
2238 442 682 692 297,5 100 Point Lynas Lt Wales 53,427 -4,292 589 303
13924 493 763 001 303,5 100 Zeven Germany 53,283 9,25 498 54
21825 492 762 001 298,5 100 Helgoland Germany 54,183 7,883 493 38
11703 449 689 699 309,5 100 Nash Point Lt Wales 51,401 -3,552 476 281
13795 447 687 697 290,5 100 Flamborough Head Lt England 54,126 -0,091 433 330
2191 494 764 001 293,5 100 Iffezheim Germany 48,833 8,117 414 120
12822 439 691 001 291,0 100 Wormleighton England 52,208 -1,374 354 298
5967 330 460 001 299,0 100 Heuville France 49,7 -1,267 339 251
3992 440 680 690 307,5 100 St Catherines Point Lt England 50,581 -1,306 318 268
12541 490 760 001 302,5 100 Koblenz Germany 50,367 7,583 313 97
28096 428 655 656 294,0 200 Vlieland Lt Netherlands 53,3 5,067 307 24
28913 426 652 653 302,0 200 Gilze Rijen Netherlands 51,617 4,933 152 52
28890 425 650 651 312,5 200 Hoek van Holland Netherlands 51,992 4,123 149 25
5428 448 688 698 299,5 100 North Foreland England 51,38 1,457 138 299
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In the past, I found that my very large EWE performed excellent towards Northwest, decoding a lot of North-American beacons.
However very soon, I need to dismantle the temporary installations (large EWE, Beverages), as they are erected over agricultural farmland, which will be needed soon to prepare for the next summer season.
I mentioned, that I want to check, how small you can make EWE antennas to still work efficiently on 300kHz. I have now installed a quick test antenna, really really small : 2.5m up, 5m horizontal, 2.5m down to resistor 700Ohm, total instead of 100m wire of the big EWE, only 10m of wire- unfortunately to make it quickly happen, it is NOT pointed to NW (over the atlantic ocean) but to Scandinavia (Northeast).
So far, I did not fine-tune the resistor value - it seems to me, that tuning is necessary, as I can see a lot of southwest Europe - look at the many decodes of Cape Ferret (which is also 'dubbed' as the Brazilian beacon as false decodes). I will try to increase the Front/Back ratio in the future.
A lot of Scandinavia was indeed heard - however the UK, was very weak, although the distance to many of the beacons in Scandinavia is larger than to the UK - this is certainly due to the directivity of the little EWE out of only 10m wire...
I must mention, that a high impedance pre-amp is used to feed the EWE - instead of the impedance matching transformer, I directly connected the pre-amp to pick up the voltage between the wire an a ground rod (1m of copper-pipe, only half inch thickness (gasinstallation material) for quick solution)
So - do not expect a lot of North-America.... wrong direction for this test antenna.
My feeling so far is, that it is really the minimum size, which will work - but only with pre-amp.
I will be better to at least double the size - make an inv. U (EWE style) out of 20m wire, instead of only 10m
Regards,
Ulli, ON5KQ
Here are the logs from late evening (22h utc) tot early morning around local sunrise:
I look forward to your test results with a 20m EWE, esp if it is aimed to North America. If they are promising, may try erecting one here. Which pre-amp are you using with it?
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Hi Chris,
I am using the LZ1AQ pre-amp.
As the EWE is not a magnetic loop, I am using directly the inputs of the voltage amplifier (Dipole) as Chavdar describes in his document: http://active-antenna.eu/tech-docs/aaa-1c-addendum.pdf (http://active-antenna.eu/tech-docs/aaa-1c-addendum.pdf)
At the moment I have removed the jumpers for the input balun, as I thought the antenna is very small...
However here in Europe I get huge signals from shortwave BC-bands even with bad condx...
The Web-receiver is using this little EWE now (although a different antenna picture is shown - I just do not have a proper picture yet)
link to the receiver: http://on5kq.ddns.net:8073 (http://on5kq.ddns.net:8073)
I notice on the webreceiver just starting IM2 distortion signals in our local afternoon (for example on 14100kHz beacons frequency) - I think even with this small loop on the shortwave bands the signals are really really strong...
So to prevent such IM2 distortion in the pre-amp (it is only noticeable, if you really search for it on the band, because the distortion is still very small), you better install the jumpers to include the input balun of the voltage amplifier of LZ1AQ's design.
With the jumpers set, you will never see distortion products coming from the pre-amp (my findings)
To enlarge the EWE to 20m long wire (so 5m x 10m x 5m) has several serious drawbacks:
- Directivity on the higher shortwave bands will disappear or at least becomes a very different pattern, instead of the desired, pronounced cadioid
- As I have transmit antennes very close (less than a wavelength), the influence of the 20m wire will be much greater to the existing transmit antennas (also vertical phased array).
-If you increase the size of the EWE, it will be much more difficult to install a multi element array out of several EWE antennas. I am planning at least 2ele arrays in several directions. Now with the 5m long invU style, it is very easy and almost unvisible to install several of such beams at the side of the garden, without using extended space on the farmland arround (more of a praktical issue)
- A larger EWE-element will help for better directivity only below 1Mhz, at the price of less or no directivity on frequencies above 10MHz - at least for summer, I prefer better directivity on the higher frequencies.
Conclusion: I think the antenna is performing well on 300khz - only the real specialist may want better directivity and increase the size. However I prefer to keep the nice performance up to the highest shortwave frequencies (30Mhz). For 300kHz, I will install a second small EWE to Northwest - so I can verify the directivity between the NorthEast one and the NorthWest one. Then to get a better F/B ratio, I will install second elements in line at both systems, for better reception of the stations in the desired direction (switchable)- spacing will be 60m initially (best for lowest frequency incl 300kHz), both elements fed with LZ1AQ pre-amps and phased 180degree - this will get you a very sharp pattern broadband over many octaves.
I used to have such an array made with Flags, but passive, without pre-amps. It was usable very well on 1.8-7Mhz - in Mediumwave or lowerin frequency it was totally deaf. With the pre-amps, this antenna really awake and is alive again... Listen on the web-receiver to verify the high sensitivity even of the single element (10m wire) system.
Will let you know further developments...
Ulli, ON5KQ