Category Archives: Antennas

Mobile Antenna Testing

I was doing some testing of mobile antennas on my F-150 this weekend. I had a mag mount on the roof, and a door-edge mount on the rear door. Both had NMO mounts, so I could easily move antennas between the mounts. Here is what I found:

I had an HT (Kenwood TH-F6A) connected to an antenna switch, connected to the two antennas. I tuned to a weak repeater. I found that I could hear it with the roof-mounted antenna, but not with the door-mounted antenna. I could switch the antennas between the 2 mounts with the same result, so it was the mount or the mount location making the difference.

When I opened the door with the antenna on it (moving the antenna and mount away from the chassis), I suddenly could copy the repeater with either antenna. I had the bottom of the door-mounted antenna about 4 inches below the roof line. moving it up about 2.5 inches made a huge difference in reception.

So if you are using one of the door-edge mounts, you may want to experiment with the placement.

Sweepstakes Results for 2012

Well I kept up the time-honored tradition of missing 1 or 2 Sections in the CW SS contest this year. Had about 575 QSOs (a personal best) and all but 2 Sections – MB and NNY. I never had trouble with a New York section before. I guess the monster storm Sandy may have been the reason, as they were all trying to get their lives back together and probably had little time for playing with radios.

I did not make any further adjustments of my ZS6BKW (ref: earlier posts on this subject). The SWR was well within usable range for the CW Band segments and I did not want to jeopardize that just before the Contest. Now that CWSS is over, I may get back to some final tweaking of this antenna to see if I can get 80m Phone in the 3:1 range needed by the IC-7600’s internal tuner.

I did try the 20m 4-element colinear antenna this year. I can’t say I was real impressed. I guess a fixed antenna with higher gain is not really what I want. Next year I may go to something rotatable. I did pickup a couple sections with the colinear that I could not get with my other wire antennas, but overall I am not sure it was worth the trouble.

ARRL CWSS 2012 – Preparation

Well, hurricane Sandy did no damage to my Chesapeake Bayside QTH. I am thankful for that and I wish a quick recovery to those that were ravaged by this nasty storm. The winds did leave one of my antennas needing attention. The winds pulled my anchor for the center of my ZS6BKW antenna out of  the ground and it is now hanging in mid air. This should not be difficult to fix.

I see from last year that we also had high winds just before SS in 2011. Guess I should expect more of that in the future. It is calm now but they are expecting fairly high winds all weekend. I will need to clean up my two existing antennas and I hope to hang the 4 element 20m colinear array on my Penninger Tilt-up mast.

Inside, my station is all ready to go for the contest. I have an SO2R setup using the Icom IC-7600 and an Elecraft K2. This year I will also be using some ICE Bandpass filters to try and reduce the Band-to-Band interference I had in past years. I tested the station, including the DX Doubler, last weekend when I operated a couple hours in the CQWWDX SSB contest. I got about 48 Contacts and added a good number of new Countries in the Log.

I really like the SO2R setup with the DX Doubler and N1MM software. I think I have all the technology pieces in place now. Hopefully I can ramp-up the Sweepstakes operation this year. I will be looking once again for that elusive (for me anyway) Clean Sweep. 83 Sections are needed this year for the Broom.

ZS6BKW Antenna

The ZS6BKW Antenna is one of many HF multi-band wire antennas. It is similar to the famous G5RV antenna, which can cover multiple HF Bands but requires an antenna tuner on most bands. The ZS6BKW follows the design of the G5RV, but makes improvements. These improvements allow it to be used on more bands, and to exhibit better SWR on several Bands. There is an excellent article that compares these two antennas, and it shows me that this is a better bet for my station than the G5RV.

I built the ZS6BKW and am now starting the tuning process for my location. I have many trees, so any wire antenna I build needs some pruning, no matter how I model it. I used standard household 14 gauge wire for my antenna and fed it with 450 ohm ladder line. I used the “fat” 450 ohm ladder-line (about 1.5 inches wide), because that is what I have available. My ladder-line uses solid number 14 conductors. That makes it a bit hard to work with, but it holds up very well to the elements at my Bayside QTH.

The one thing I dislike about this antenna is that it is not expected to work on 15 meters, where it has a very high SWR. I can use my 135′ dipole on all bands with my antenna tuner, so I am wondering if this antenna gives me any advantage over that. It is shorter, but I have room for the 135′ wire, so maybe this is a compromise I do not need.

I will be trying it and tweaking the dimensions. I’ll post my results for anyone that may be interested in the ZS6BKW.

Antenna Design: 20 meter 4-element Colinear

After looking at articles in the ARRL Antenna Book and on L.B. Cebick’s web site, I thought a 4-element colinear wire antenna might be useful for my station. I currently use only wire antennas which work fine on 40 and 80 meters, but on the higher Bands, I need some gain. My main goal is to be able to improve my ability to reach Stations in the Northwestern US and Canada. Since this is a bi-directional antenna, it will also help with my DX contacts.

This is a classic antenna design that has been used by many people. I am not claiming to be doing anything unique here. I am just keeping some notes to track my attempts to make this antenna work at my QTH. There is an excellent description of HF Colinear antennas in the ARRL Antenna Book.

Here is the basic design of the antenna

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The picture of the antenna above is a little hard to see. It consists of 4 half-wave elements in a line, with two quarter-wave stubs between the pairs of elements. Each stub is a piece of ladder line, with the end shorted. This provides the necessary phase shifting to align the half-wave sections to provide gain. The antenna is fed at the center and the feedpoint impedence is near 450 ohms.

In case anyone is interested in experimenting with the EZNEC model, here is the listing of the wires for this antenna.

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Note – this is just one trial set of element lengths. It may not be ideal for any particular location, and may not even be the actual dimensions I use in the final antenna. But if you have EZNEC, you can take it from here and see what works for you.

20 Meter Colinear Antenna Project

I like to try a new antenna every year for one of my favorite contests. A year or two ago I had great hopes for a 20 meter Colinear wire antenna in the ARRL CW Sweepstakes. I ran out of time and threw one together quickly. It did not do much for me, but I think the implementation was really poor.

So I am going to give it another try. This time I am modeling it with EZNEC. I started a model last go-round, but never really got to the point that the dimensions were very good. I suspect I was not getting nearly the gain it promises.

There is a good write-up in the ARRL Antenna Handbook about this antenna. If you have any interest in HF antennas, and you do not have this book, what are you waiting for? This is the definitive practical reference book for HF (and VHF/UHF) antennas. My other favorite antenna reference is the LB Cebick (Silent Key) Web Site. LB was a prolific author and antenna enthusiast. I have purchased several of his antenna models and some of his books. This is very practical stuff, and extremely easy to read.

My 20 meter colinear will use four half-wave elements. The goal is to get a decent signal into the far Northwest of the US and Canada. That has always been my biggest difficulty in trying to work all Sections in the Sweepstakes.

IC-7600 Antenna Tuner Testing

I did a bit of testing with 2 wire antennas this weekend. Here is a summary of the results, which I also posted to the IC-7600 e-mail reflector:

The antennas:
1 – A “long” 80m Dipole, ladder line, 4:1 balun, then a long coax run
to the rig
2 – A fan dipole with 80/40/20 meter elements (these are close-spaced
elements, with 80m and 40m using opposing legs of a single piece of
300-ohm twinlead), 1:1 balun, then a long coax run to the rig

This was a brief test. I tried only 10/15/20/40/80 meters, and tested
only a few frequencies on each band, including something close to the
bottom and top of each band.

The IC-7600 internal tuner was able to tune both antennas over most of
the 10/15/20/40/80 meter bands with the following exceptions:
1 – Could not match the 80m Long Dipole at the high end of 80m or
anywhere on 40 meters
2 – Could not match the Fan Dipole anywhere on 20 meters

The External LDG-100 PROII was able to match all the test frequencies.
The IC-7600 tuner is very good, and tuned most of the frequencies,
including some that appeared to be worse than 3:1 SWR (the stated
spec) on my antenna analyzer.

Please note – I am NOT knocking the internal tuner, and with a little
antenna work (pruning antennas and feedlines – not fun) I could
probably get matches everywhere I need to operate. So, while the
internal tuner is very good, the LDG (which has a nice ICOM interface)
covers a wider range. The LDG was sometimes very slow (10s of
seconds), but once a match is found it is stored and recalled quickly
next time you need it.

Icom IC-7600 Added to the Shack

I have been looking to purchase a new rig for some time and finally decided to go with the Icom IC-7600. I was torn between this rig, the Elecraft K3, and the Yaesu FT-2000 (because I can not afford the FTDX-5000). For my needs, this is the best of the three. and I will maintain my complete K2 station as my “second receiver” and for use in contests in SO2R mode.

I have had the IC-7600 for a few weeks and have had a chance to do a bit of testing. I worked a short stint on a RTTY contest, a 10-hour CW contest, and made a few SSB and PSK-31 contacts. Operating the rig has been very enjoyable so far. It just seems to be very well thought-out and the IF DSP filtering is outstanding. The built-in RTTY and PSK decoders are great. Just plug-in a USB keyboard and go.

The internal antenna tuner works great but only handles up to about 3:1 SWR. Since I have some “ugly” wire antennas, I have acquired an LDG external tuner – the AT-100 PROII. It has an Icom interface that integrates it nicely with the rig (as well as the internal tuner, in my opinion). It definitely allows me to match a broader set of antenna situations than the internal tuner (as the specs would lead you to believe).

ARRL CW Sweepstakes 2011 Diary – Preparation

Preparing for CWSS this year mainly consisted of antenna work and integration of the SO2R (Single Operator Two Radio) setup in the Shack. I use mostly wire antennas (no Yagis) but one, a “Fan Dipole” (one design example found here) for 80/40 meters had been hanging for several years. I took it down to check the condition and found one of the wires was broken at the center insulator. No big surprise given the winds on the shore of the Chesapeake Bay. I refurbished the antenna and added a 20 meter element. I really like these Fan Dipoles (more on that later). When you can put up a dipole, why not hang 2 or 3 at the same time?? Something for nothing?

I added a second antenna and planned to add a third. I now have two dipole/doublet antennas oriented in nearly the same direction. This supports my 2-radio operation but does not help much for directivity. When you use a doublet there are several directional lobes, resulting in some dead spots in the far field. Having another antenna, perpendicular to these, would smooth out the dead spots.

Unfortunately, when I arrived at the operating QTH  the day before the contest, a steady wind of 30 MPH or more was blowing. Cancel plans for the third wire antenna. I have a 6BTV Vertical antenna, so I put that on a ground post, just in case something happened to one of my wire antennas during the contest. I also found that the center of one antenna was about 8 feet lower than normal. A broken limb had become entangled in one of the end supports. Nothing I could do to fix that today, so I go with a slightly lower antenna for the contest, and hope it stays in the air.

In the Shack, I was nearly set for the contest and just needed to fire up the station and make sure N1MM and my DX Doubler (DXD) were ready to control everything. I had previously used an old laptop and recently replaced that with a small (mATX form factor) PC that was more “server-like.” About an hour before the start of the contest I realized that the DXD was not being controlled properly. The TX Focus was not switching between the radios from the keyboard. It turns out the PCI-based parallel port I added was not working. No time to play with that – back to the Laptop.

Now everything appeared to be ready to go.

Antenna Tuner is Too Smart

Automatic antenna tuners are great. Just tune your radio to the frequency you want, flick the TUNE switch, and you quickly get an optimum match between your rig and the antenna. Well, not always. I have an ICOM IC-7000 with an LDG AT-7000 antenna tuner. This is a great little tuner, but it sure tricked me this time.

I wanted to try my rig on the 6 meter band for the first time. So I set up the station and was listening around for signals during this weekend’s VHF contest. There are some CW beacons I had heard before, so I tuned to that part of the band, activate the tuner, and heard nothing. Then I hit the TUNE button again, bypassing the Tuner, and the beacon suddenly appeared! So I hear no signal with the Tuner doing the matching, but I hear the beacon when I bypas the Tuner.

After noticing that the SWR was indeed lower when the Tuner was inline, I realized what was happening, The Tuner has many memories. If it found a “good” match at a frequency, it uses that information to shorten the tuning cycle next time you go to that frequency. The Tuner had apparently found a match that provided a low SWR, but it also resulted in a lossy signal path. The instruction manual showed me that I could go into the Tuner case and push a switch that would force it to retune, even though it thought it had a good match already. So I pushed the button, the relays clacked, and presto, a good match and the beacon reappeared. Guess this button should be on the front panel! Then I worked my first 6 meter station ever.

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