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When it comes to discussion of 630m, the topic of antennas seems to top the list. One of the easiest ways to enjoy what 630m has to offer is to try and utilize a low band antenna that may already be in place. An 'inverted-L' for 80 or 160 can be readily bottom-loaded and with a few radials, can provide a good starting point ... but with a little additional work, its efficiency can be easily improved by expanding the top horizontal (top hat) section.

Jim, W5EST, has posted an interesting description of the pros and cons of the 'top hat' in a recent KB5NJD daily 630m report. Those thinking about getting on the band or those considering ways of improving their present antenna might find the information helpful.

Top Hat Advantages:

Higher EIRP comes from a more nearly uniform current distribution all the way up a TX vertical. https://en.wikipedia.org/wiki/T-antenna . But remember that adding top hat doesn’t help you if your license is subject to a legal limit EIRP that’s reached by your station already.

A vertical without a top hat has no current at its tip, meaning the upper part of a hatless vertical is inefficiently used.  Average RF current for a hatless short vertical is only half what an RF ammeter shows at the antenna base.  Top hat lets a shorter vertical antenna yield same total radiated power TRP by increasing its degree-amperes, as discussed March 31, this blog.

2 amperes of 630m RF base current in a 10° tall hatless short vertical can give 10 degree-amps (2 x ½ x 10°) and yield 15 degree-amps with an ample top hat.  A top hat can increase average RF current by about a quarter to half, which could as much as double the TRP.

Top hat increases antenna system capacitance. You get more flexible QSY by decreasing the system Q.  SWR increases rapidly as your frequency departs from antenna system resonance, see graph Feb. 10, this blog. With lower system Q the SWR doesn’t increase so rapidly. Then you can QSY temporarily a little way without retuning or by just retuning a little in the shack instead of outdoors at the ATU.

Decreased Q somewhat lowers antenna voltage KV from antenna base to top hat. On 630m Q = (2π 475)L/R by definition and Vantenna = 1.4 Q  P / I  <  Vbreakdown.  See Jan. 16, this blog.

Top hat wires can be symmetrically or asymmetrically positioned to give approximately similar capacitance whichever way.   I’ve not modeled the effect of a top hat on the azimuth and elevation antenna patterns of an electrically short vertical.  I don’t think the effect is very significant. But if you know a link or some better information about this, let us know.

If your radials have extended way beyond the extent of a small top hat high above, then providing longer top hat conductors above the radials can more efficiently utilize the radials.   If the radials mostly go in one or two directions, then for highest antenna system capacitance the hat wires should extend in those directions to couple best with the radials.  Your experience may suggest this last is not too important, especially if you have a perimeter conductor and/or several ground rods and your soil has favorable conductance.

Another top hat advantage is that top hat conductors are compatible with structural support and stabilization for the very top of an MF/LF vertical antenna.  You get added degree-amperes–and steadying at the top to boot.

If the top hat slants upward, its system capacitance contribution is somewhat decreased compared to a top hat of same length horizontally, but the vertical slant contributes radiated power. Depending on the arrangement of antenna and trees on some properties, using a shorter vertical with an upwardly slanting asymmetrical top hat may make the antenna system both easier to guy and less obvious to neighbors.

Putting in a top hat or improving a top hat increases the degree-amperes of a short vertical mainly by distributing the same RF amperes more uniformly.  Adding more radials and longer radials decreases the antenna system resistance and increases the degree-amperes of a short vertical mainly by increasing the RF amperes of antenna current itself.

Top Hat Disadvantages:

A top hat obviously requires outdoor work to construct or revise it.  You may be able to simply increase your transmitter power TPO more conveniently than to do the outdoor work.

A top hat needs to extend more or less horizontally from the top of the vertical, although the angle is not too critical within +/-45°.  Distant supports for the top hat at that top level may be unavailable or expensive and inconvenient to provide. If the top hat were attached to the vertical below the top of the vertical, the otherwise radiation-beneficial top segment of the vertical becomes mostly unused.

If the top hat slants quite steeply downward, its effect on system capacitance may be a wash– more capacitance by closer approach to the ground and less capacitance because same length top hat conductor extends less outward over the ground below. That defeats a reason for putting up a top hat in the first place.

Moreover, if the top hat slants steeply downward, then vertically downward RF current in the top hat cancels part of the radiation from the vertical antenna and at least partially defeats the improvement in vertical antenna current uniformity that the top hat is intended to confer.

A long top hat may not fit on the available real estate.  Even if it fits, it may add to visibility as far as difficult neighbors are concerned.

Adding a top hat means you need to retune the ATU after the addition. But so does improving the radials or just about anything else you do.

Top hat conductors add more weight on a vertical than lighter-weight guying does.  The weight of the top hat likely adds to the support demanded of the antenna base.  If you put downward-slanting top hat conductors under tension at their far ends to keep them from drooping in the middle, then a lot of that tension will be imposed on the vertical too.   That can produce a buckling force on the vertical which may call for additional guying halfway up the vertical.

Top hat conductors convey a declining but substantial RF current along their length.  That involves I2R losses in the skin effect resistance of the top hat conductors. However, if your earth resistance is high or your radial/grounding system is not very elaborate, some loss in the top hat probably does not decrease the RF amperes of antenna base current very much at a given TPO compared to the improvement in radiation TRP that the top hat gives you.

If skin effect resistance losses in the top hat are significant compared other losses in the system, reducing top hat losses generally means more conductors or heavier conductors in the top hat.  That translates to more weight for the whole system to support.

A top hat translates KV of antenna top voltage to its ends. If the top hat extends all the way to leaf cover of trees or shrubs, unexpected sparks might jump to them in quiet weather, or in windy weather, or sometime when such trees or shrubs grow nearer to the top hat end(s).

Generally top hat advantages outweigh their disadvantages so long as you plan intelligently. Please tell us your experiences with top hat advantages and disadvantages!”

A G3XDV LF top hat

Jim often adds an interesting op-ed piece to the KB5NJD daily report and sifting back through the past few weeks will provide some great 630m 'food for thought' bed time reading!

Today's Sun courtesy: http://sdo.gsfc.nasa.gov/

With the sun remaining reasonably quiet over the past several days, a sudden spike in the geomagnetic field on Saturday afternoon saw a number of trans-Pacific spots showing up on 630m WSPR mode.

courtesy: http://wdc.kugi.kyoto-u.ac.jp/

In the predawn hours of Sunday morning, my own system decoded the VK3ELV WSPR beacon, located in south east Australia, 12,992 km from here. From an e-mail exchange, it seems that VK3ELV is using a 'drifting' IC706M2G on 10Mhz with a VK3XDK Transverter into an old HF AMP (2x 2SC2290) modified for 630m. This is running about 130-140 watts output. The antenna is an inverted L about 30 metres high and 1/4 wave long.

courtesy: https://www.google.ca/maps

VK3ELV 630m

Further to my south, the WG2XGP WSPR beacon run by Larry, W7IUV in central Washington, was reported down under by two different VK's on Sunday morning as well ... VK4YB and VK2DDI, both some distance from VK3ELV.

courtesy: https://www.google.ca/maps

It's interesting to note the time difference for these receptions, with Larry's reception being several hours earlier than my own (1304Z), close to my sunrise. As well, the 'spotlight' effect of propagation over such a vast distance is somewhat intriguing. I would have thought that if I should see any VK's on 630m, it would be the closer ones and not the further one, yet it was just the opposite.

Although VK3ELV's signal was right at the edge of WSPR decoding levels (-29db), it would only take a few more db to allow a two-way JT9 digital mode QSO to take place ... maybe something that will be possible in the coming years of solar minimum and much better LF/MF propagation. To be readable on CW would need an equivalent true power output increase of at least 16 times, requiring VK3ELV to run around 2,000 watts output!

Over the years I have seen ZL6QH a number of times on 2200m (QRSS CW mode) but this is my first reception of VK and, hopefully, not my last.

To keep up to date with overnight activities on 630m, visit the excellent site of KB5NJD. John posts a detailed daily summary of events. In addition, you will find some excellent resources to help you get involved in this part of the spectrum ... and remember, you don't need a big backyard or a big antenna to have fun on 630m.

Toby, VE7CNF, has sent me some mail indicating that his new lightwave system is ready for a two-way test!






His system is very similar to the ones built and deployed by myself and Markus, VE7CA, in late 2013. The culmination of that activity is described here, in 'On Making Nanowaves - Part 6'. Our lightwave QSO and homebrew gear were later described in a 'how to' article in the 'The Canadian Amateur' as well as in the newest edition of  'The Radio Amateur's Handbook' (2016).

Toby describes his most recent pre-QSO backyard testing:

The lightwave gear appears to be working well. Focus looks good and the
finder scopes are doing their job. There's a reflective sign high up on a
hydro tower 170 meters away that's handy for testing. It lights up bright
when the transmitter's on it.

Back scatter off the clouds above my house worked too. I heard my CW beacon, audible 339, off a patch on the clouds about 1 degree wide. I don't really know if it was clear air scatter from closer by, or scatter off the clouds, but the spot was small. That's with the tx on the front deck, and rx in the back.

I used Spectran to check the noise from city lights in my area. At QRSS10
speed there are spectral lines at 540, 600, and 660 Hz. They aren't too
strong, but those are some frequencies we should avoid.

VE7CNF's lightwave system - TX (L) & RX (R)

As well, Mark, VA7MM, is also putting together a similar system to join the fun ... it's great to see new local activity!

Hopefully the weather will co-operate enough to allow us to make a two-way QSO later this week. Plans call for Toby to set up near the same location in West Vancouver used by VE7CA as it offers a clear LOS path to Mayne Island, 54km to the southwest.

54km Georgia Strait crossing (courtesy: https://www.google.ca/maps)

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Rik, ON7YD, has set up a new website devoted to information specific to 630m. His 472kHz.org site looks as if it will be a valuable resource for those looking to get information and a start on our new band. At present, there is some really great information regarding transmitters, antenna systems and calculating E(I)RP levels. Have a look!

As the rollout of new LF and MF ham bands grows closer for U.S. amateurs, earlier this month, the ARRL requested the FCC to carefully consider the procedural requirements governing the advance notification of local electric authorities of their intended 630m / 2200m operation. The FCC had suggested that under certain circumstances (mainly the distance to the nearest PLC signal-carrying power lines), amateurs would be required to notify and co-operate with power authorities ... but it was all very vague and seemed to place the conditions under which operating authority would be granted into the hands of the power companies.

In what appears to be a preemptive move to head-off the (possibly) overly onerous and impossible roadblocks suggested by power company representatives, the ARRL filing states:

“ARRL does not object to such a notification requirement, provided that it is appropriately circumscribed, not overbroad in its applicability, and not overly burdensome for radio amateurs to comply with,” the League’s statement asserted.

In addition, the power authority Utility Telecom Council (UTC) has been notably silent on the issue ... slowing the process even further.

"The ARRL noted that comments filed by the Utilities Telecom Council (UTC) called for a system of “quasi-coordination” by radio amateurs before commencing operation on 2200 meters (135.7-137.8 kHz). In its remarks to the FCC, the ARRL pointed out, however, that the UTC has not volunteered any information with respect to how a notification process might work nor offered any PLC database information to the ARRL or to the amateur community so prospective users of the band could determine if their operation might be problematic."

The League took the opportunity to remind the FCC, once again, that the low ERP levels generated by amateurs operating on the new bands would have a low probability of creating any interference and further pointed out that PLC systems operating between 9 and 490 kHz are not subject to protection from licensed services.

The ARRL also indicated that any sort of blanket notification requirement prior to transmitting on 2200 or 630 meters “would be clear regulatory overkill,” and that utility companies should clearly be required to demonstrate how amateur operations would cause harmful interference to their PLC (unlicenced) operations.

It's good to see the ARRL still being proactive with regards to procuring these new frequency allotments on behalf of U.S. amateurs ... hopefully making implementation sooner rather than later. The entire ex parte filing can be read here as well as the ARRL's own news posting of the procedure here.

In the meantime, I'll make yet another call-to-arms to fellow Canadian amateurs, who already have these two new bands but aren't using them ... new activity from the western provinces would be especially welcome as there are a now a number of well-equipped stations in VE7 who would like to work you.

Those of you that have been following the recent set of four YouTube videos posted in my recent PAØRDT Miniwhip Shakedown blog, regarding the care and feeding of the PAØRDT active e-probe antenna, may be interested in a fifth video in the series, posted by Mike in the U.K.

PAØRDT's recent modification of the isolating transformer, in the miniwhip coupling unit, provides much better immunity to common mode noise-coupling in the HF bands. Mike shows the installation and operation of the new unit along with some additional grounding out at the antenna.


Those of you that are looking for a possible solution to relatively good reception on LF or on the 630m band, might find the answer with a carefully thought out installation such as the one shown in Mike's video series.

Although living in the suburbs often means dealing with a lot of noise, particularly on LF / MF, Mike's system shows that excellent low noise reception is indeed possible. It is important to 'probe' your backyard with the antenna itself in order to find the quietest location for installation.

More information on the PAØRDT miniwhip and other low-noise LF / MF antennas may be found in previous blogs here.

With a very quiet sun for the entire week, this past weekend's CLE proved to have much better conditions than normally experienced.


Conditions were 'good' but not 'great'. Really 'great' nights are few and far between but with the rapidly declining solar cycle, we should see more and more of these over the next few winters.

Most listeners around the world reported good conditions, with the nod going to Friday night as being the best. I thought that all three nights were good, but heard nothing new on night number three.

A surprise catch, with a good signal, was 'BRA -379' in Asheville, North Carolina. It's classified as an 'H-class' NDB and is an outer marker locator. I believe the H-class indicates a 400W transmitter and with the large vertical antenna, seems to get out very well.

courtesy: http://www.bing.com/maps

Even more surprising was 'SPH-375' located in Springhill, Louisiana. It is an LOM ndb, being co-located with the runway's ILS outer marker. The beacon appears to be using the classic "T' as seen here and is likely in the 25 watt range.

courtesy: http://www.bing.com/maps

As I mentioned earlier, I was rather dreading this CLE since my local blowtorch pest signal (AP-378) was smack in the middle of the CLE's frequency range. 'AP' is located 6/10ths of a mile from me, just down the shoreline and has a huge signal here.

Fortunately, Perseus has an extremely effective 'notch' filter, and this, along with putting 'AP' in my LF loop's null, allowed me to hear two other NDB's beneath it ... 'ZFA' (Faro, Yukon) and 'UX' (Hall Beach, Nunavut).

The following 44 stations were heard on the Perseus SDR while using either the LF loop or my inverted 'L', tuned to 370 kHz.

27 06:00 370.0 YBV Berens River, MB, CAN
27 06:00 370.0 PAI Whiteman, CA, USA
27 06:00 371.0 YK Yakima, WA, USA
27 11:00 371.0 UK Laughlin, CA, USA
27 06:00 371.0 PUR Marshall, MO, USA
27 06:00 371.0 ITU Great Falls, MT, USA
27 05:00 371.0 GW Kuujjuarapik, QC, CAN
27 06:00 372.0 ZPA Prince Albert, SK, CAN
27 08:00 372.0 YCO Kugluktuk, NU, CAN
27 05:00 373.0 MF Table Rock, OR, USA
27 06:00 374.0 LV Livermore, CA, USA
28 09:00 374.0 HY Hays, KS, USA
27 05:00 374.0 EX Kelowna, BC, CAN
27 08:00 374.0 EE Forada, MN, USA
28 09:30 375.0 SPH Springhill, LA, USA
27 05:00 375.0 FS Fort Simpson, NT, CAN
27 07:00 375.0 CP Casper, WY, USA
27 08:00 375.0 BM Balmoral, MB, CAN
27 08:00 375.0 BD Moose Jaw, SK, CAN
27 08:30 376.0 ZIN Matthew Town, BAH
27 07:00 376.0 YAG Fort Frances, ON, CAN
27 05:00 376.0 PVQ Deadhorse, ALS
27 07:00 376.0 LC Columbus, OH, USA
27 09:00 377.0 EHA Elkhart, KS, USA
27 08:00 377.0 BUB Burwell, NE, USA
27 08:00 378.0 ZFA Faro, YT, CAN
27 05:00 378.0 UX Hall Beach, NU, CAN
27 07:00 378.0 OT North Bend, OR, USA
27 05:00 378.0 AP Mayne Island, BC, CAN
27 08:00 379.0 ZEG Edmonton, AB, CAN
28 11:00 379.0 IWW Kenai, ALS
27 07:00 379.0 DL Duluth, MN, USA
27 08:00 379.0 BRA Asheville, NC, USA
27 10:00 380.0 OEL Oakley, KS, USA
27 08:00 380.0 GC Gillette, WY, USA
27 05:00 380.0 BBD Brady, TX, USA
27 08:00 381.5 SJX St James, MI, USA
27 10:00 382.0 YPW Powell River, BC, CAN
27 10:00 382.0 YE Fort Nelson, BC, CAN
27 06:00 382.0 SP Springfield, IL, USA
27 08:00 382.0 JNR Unalakleet, ALS
27 08:00 382.0 AW Marysville, WA, USA
27 10:00 383.0 PI Pocatello, ID, USA
27 07:00 383.0 CNP Chappell, NE, USA
27 10:00 384.0 3F Ile-a-la-crosse, SK, CAN

The listening results for all North American listeners and those outside of Europe can be found here.