Tag Archives: Antennas

The Half Square Antenna

I am planning to assemble a 20m Half Square antenna this weekend. The vertical sides will be 17 ft long and separated by 35.4 ft of wire at the top. I am planning to voltage feed this antenna with the EFHW matchbox. I should be able to angle this so that the radiation is at a bearing of 40° for European DX. This configuration should not require any ground radials and promises about 3dB gain over the vertical:

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This antenna should be fairly easy to deploy with two fishing poles

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40m FT-8 to Asia Working Again

I have been having good luck working DX into Asia on 40m FT-8 the past few mornings. The opening have lasted here well after sunrise until about 8:30am local time. I have made numerous contacts the past few mornings into Japan, Indonesia & the Philippines. The band had seemed to be shifting but it was likely just poor propagation conditions. Glad to be working these contacts again.

Inadvertently Stress Testing a Homebrew Buddistick

I took out my homebrew Buddistick over the weekend to test its performance versus the full size verticals I have been playing with. I haven’t really deployed this in some time so I was able to make some comparisons to some of the antennas I have been working with lately, namely the 1/4 wave ground mounted verticals. Setup up was about as easy as I remembered it but certainly more complicated than the ground mounted vertical. It is also heavier than I remembered it to be. I had it setup with three guy lines and a single elevated radial and it tuned to 1.46 SWR on the 20m band. On 20m it is not a full size radiator and relies on a small coil to bring it to resonance.

Performance was actually quite good on 20m WSPR. Two days in a row I made the WSPR challenge board. It still remains about 20 spots below the nearby station of N5CEY. The number of spots on 1/2W transmit was about equal to the number of receive spots which I am finding to be a good indicator of antenna efficiency. Thais tells me what I already knew, that is, it is a good QRP field antenna.

The antenna went up Saturday afternoon and stayed up through Monday afternoon. Monday it got breezy here at the QTH. Wind speeds picked up to around 20mph with gusts to 35mph. At some point, the camera tripod failed at the point where the PVC pipe meets the tripod. The whole mess came down hard. Fortunately, the whip was spared any damage and the tripod can be repaired.

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For my next trick I am going to try and replace the whip with a fishing pole and wire with an elevated radial. Should be much lighter. It has also proven to be much more resistant to the “valley Wind Machine” that builds up around here this time of year.

A new Antenna Analyzer Gadget – RA0SMS miniVNA

It took about a month but yesterday I received a 1-30Mhz miniVNA that I had ordered on Ebay from RA0SMS in Russia. I have previously bought a miniWhip antenna from Anton with good results. This unit is based on a design by RA4NAL.  This is an interesting unit as it is Arduino controlled and provides a two port capability for only $75. Here are the basic specs:

Specifications

• Frequency range 1-30 MHz

• Calibration using open-short-load for accurate results

• RF Generator with output power of 1,5 V @ 20 MHz

• Low power consumption, 400mA @ 5 V

• BNC connectors for better isolation

• User friendly interface for PC (Windows)

• Export data in several formats – JPEG, EXCEL, ZPLOT, S2P, PDF

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This unit receives power and interfaces with a PC through the USB port. Unlike a stand-alone antenna analyzer, this unit requires a PC to operate. The advantage to using a VNA over an antenna analyzer is in testing filters, measuring insertion loss, determining the types of an unknown ferrite toroid, etc. There is a great write up on the uses of a miniVNA on N4SPP website.

I have not had a chance to test this unit extensively but I have installed the software (downloaded from the RA0SMS website) and tested that it powers up, is recognized by Windows 7 and performs a basic sweep. The device was painless to install. I have bought a couple of BNC to binding post adapters as well as a couple of BNC to UHF adapters to facilitate use around the shack. Lastly, I will build a set of Open, Short and load connectors to do a calibration on the device.

The software appears to be full featured but is not supported or in current development. There is a Java based software by DL2SBA that is supposed to work with this (when miniVNA is selected) but I have not tested beyond installing on my PC. I’ll post more on this when I get a chance to calibrate and then put it through its paces.

North American QSO Party – SSB

Saturday morning was a bit hectic for me this week as I had some errands to run early. I finished up by 17:30 UTC and started to setup for the North American QSO party. I decided to deploy the 2 element 20m vertical beam. I had taken it down due to inclement weather so this was a good test on how long it takes to setup in the field. All told it took about 30 minutes and that was doing things slowly. I have it pointed on a roughly North bearing.

I started operating the North American QSO party just after 1800 UTC and operated off and on through about 0000 UTC. I started on 20m and there was a lot of activity on this band. The 15m band was open but with much lower activity. 40m started coming alive at around 2200 UTC. Working search and pounce at a rate of about 25 Q’s per hour. All in all I ended up with 120 QSO’s to 106 unique call signs. I managed to work 40 US states, Barbados and several VE stations.Top state was California at 18.3% followed by 9.2% in Washington and 7.5% in Florida. Overall a decent effort with casual contesting.

It’s Been Quiet…too Quiet…

It has been almost two weeks since my lasts posts. Radioactivity has been largely on the back burner due to finishing up family holiday activities, getting back to work at the start of the year and unusually cold weather here in South Texas this year.

Most years we have been able to count our winter in days. This year it will likely be in weeks. Definitely prefer working outside on antennas when its cold versus the extreme heat in summer but the last few cold spells have also been rainy as well. My main antenna right now is the 1/4 wave vertical for 40m. I use it on 40m, 20m and 15m. I also still have up the Ultimax DXtreme end fed but rarely use it anymore. My next activities are to try a 43 foot vertical using a spiderpole and then finally setting up the S9V31 permanently.

Tomorrow I am hoping to operate during the NA QSO party. Operation will be casual. Next weekend is Winter Field Day which I may try and do portable if it is at least dry.

20m Vertical Beam Now Pointing to Japan

I moved the driven element of the 20m vertical beam to a bearing of about 330 degrees today. it took only about five minutes to drive in the pvc mounting pipe And rearrange the ground radials. The driven element is now further away from the A/C noise so that is now tolerable.

Early morning in Japan, signals started coming in and this time the difference between the vertical and the beam are significant. The S-meter indicated about a 2 unit difference. I did not close a QSO on phone but made a JT-65 to Japan.

Tomorrow I will collect some WSPR data and share a comparison method I am trying out.

 

More Tests of the 20m Vertical Beam Antenna

EZNEC modeling suggested a better response if I moved the elements of the 20m 2 element vertical beam closer together. The separation distance is now 11 feet versus the previous 18ft. Hard to tell if this worked on the basis of QSO’s completed. I will likely move the driven element so the array points to an azimuth of 330° as Japan seems to be opening up in the late afternoon.

20m 2 Element Vertical Beam

I built and am testing a 20m 2 element vertical beam antenna today. I started by setting up a 20m 1/4 vertical tuned to about 14.2Mhz. The vertical element is 15′ 1″ of #14 house wire supported by a fiberglass fishing pole.

There are four ground mounted radials measuring 18′ 6″ using #18 speaker wire. Once this was setup, I setup a duplicate antenna with a vertical element length of 15′ 8′ as then director. This element is connected directly to four ground mounted radials as with the driven element. The two vertical elements are about 16 feet apart and lined up to a bearing of about 40°

So far all went well and the antenna is resonant across the 20m band. I had one contact on SSB with a station in Alabama who gave me a 59 with the beam and a 57 with my 40m vertical running on 20m with the tuner. A similar case with a station in Indiana who had me 20 over S9 using the beam and an S8-S9 with the vertical. Two contacts on the back side were workable with my reports at a S7-S8. I am running on WSPR now and will collect some more data.

Don’t Drop the Toroid!

I sat down to start working on the phase transformer for my phased vertical project. I dropped the toroid!

Sigh!

Just ordered a replacement. Hope it arrives before I break for Christmas….