Receiving SAQ and other VLF stations

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The huge VLF antenna of SAQ near Grimeton, Sweden (credits).

This article is about receiving radio stations operating in the VLF band (3-30 kHz). Due to the very low frequency, receiving such stations requires some special equipment, since most radios don’t support these low frequencies. One of the interesting stations in this band is SAQ, which occasionally transmits at 17.2 kHz. Other stations include submarine communications and time services. — more →

Short DL6WU yagi for 23cm

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My 23cm yagi antenna, in fixed position to the local ATV repeater.

In the previous Winter I built a HB9CV-in-a-box for 23cm for my uplink to the local ATV repeater PI6ATV. Although this antenna works nicely, its gain just isn’t enough when their 23cm preamp is broken (which, unfortunately, is the case most of the time). To achieve a more steady uplink, I decided to build an antenna with a bit more gain, at least 6 dB extra compared to the HB9CV. A short yagi should make this possible. — more →

5/8 Wave vertical antennas for HF

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Our 5/8 vertical for 20m, during a windy day.

Lots of radio amateurs build their own verticals. Most of them tend to stick to vertical antennas with a 1/4 or 1/2 wave sizing. Just a happy few build a 5/8 wave vertical antenna. This is remarkable, since the 5/8 has the lowest angle of radiation and has about 1dB more gain (compared to 1/4 and 1/2 verticals). So the 5/8 should be the favourite choice for DX’ing.

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70cm bicycle antenna

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My bicycle with 70cm J-pole antenna attached to the carrier.

During the summer season I sometimes travel to work by bike. It’s a 21 km trip through the countryside, passing cornfields, orchards, deer and spoonbills. The road includes dikes and bridges, and even a ferry to cross one of the branches of the river Rhine. Especially in the early morning it’s a real pleasure to enjoy all the surrounding nature.

I thought it would be nice to chat with some local radio amateurs on my way back home. I often talk to Adrian PA0RDA while driving home (by car) after work, using the local 70cm repeater PI2ZST, so I decided to prepare my bike for this UHF band. — more →

A very small active antenna

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The kit contents: extensive documentation, a professional circuit board, and all necessary components.

Small active antennas like the “mini-whip” (by PA0RDT) are very popular at the moment. They provide good reception of signals from HF all the way down to the VLF band. Here in the Netherlands Van Dijken Elektronica sells a nice kit for this antenna, and since Adrian PA0RDA was interested in this antenna, I ordered this kit and built it. — more →

HB9CV-in-a-box antenna for 23cm

The antenna is mounted in my pole, just below the 23cm LNC. Both are pointing at the PI6ATV repeater.

The antenna mounted in my pole, just below the 3cm LNC. Both are pointing at the PI6ATV repeater.

The HB9CV has been a popular antenna for decades, especially on the 2m band where it is commonly used for direction finding (foxhunt). Others create arrays of HB9CV antennas for DXing. Since I needed a simple antenna for 23cm (to uplink to the local ATV repeater PI6ATV) I thought it would be nice to use this HB9CV design.

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Is our 80/160m HEDZ suitable to work Americans at 160m?

Adrian PA0RDA and his Drake TR-7

Adrian PA0RDA and his Drake TR-7

Last weekend was the yearly ARRL 160m contest. Adrian PA0RDA and I were still a bit in doubt about our HEDZ antenna for 80 and 160m: is it suitable to work American and Canadian stations at 160m? So far we never heard any station from that area on that band, so Adrian decided to bring his Drake TR-7 for the weekend and try to work these countries during the 160m contest, probably the best opportunity for this test. — more →

J-pole antennas for HF bands

Introduction

I’ve been using J-pole antennas on the 2m band from the first day I got licensed. They perform very well, are easy to construct and are cheap. Since Adrian PA0RDA and I have been experimenting with vertical antennas for HF, we came to the idea to try those J-poles on HF.

This idea is not new. Many radio amateurs have tried this before, like DK7ZB. The J-pole antenna is almost identical to the Zepp-antenna, which is a still a popular HF-antenna. — more →

Automatic antenna tuner using an Arduino

Introduction

OLYMPUS DIGITAL CAMERAThe Arduino board is a fantastic tool for rapid prototyping, and can help radio amateurs in lots of homebrew projects. I wanted to demonstrate that it is very easy to build an automatic antenna tuner with the Arduino. I connected an old SWR meter to one of my Arduino boards. Furthermore I build a simple L-tuner with a fixed coil and a rotating capacitor (400pF). The capacitor is driven by a servo, also connected to the Arduino. By doing a full sweep with the capacitor, the Arduino tries to find the position with the lowest SWR. After the sweep it turns the capacitor to that position. You can view the video below to see the tuner in action. Mind the SWR meter (right needle) in the back while the capacitor is rotating. — more →

Squalo antenna for 6m

Introduction

squalo-6m-1Adri PA0RDA, a friend of me, is trying to do some DX on 6m for a while now. His antenna position is very poor: he lives in the bottom flat of a 5-floor building. He has a balcony on the rear (south) side, but high buildings are very close, he has no direct sight in any direction. At the balcony he has a Diamond V2000 vertical antenna for 6/2/70, and an MFJ loop antenna for 15-40m. The 6m band is his most popular one, since he get best results on this band. However, since most DX on 6m is horizontally polarized, he needed a horizontal antenna. I remembered an all-direction horizontal antenna made by Jan PA3EGH (one of the members of the local radio club). So I contacted him, and he pointed me at his website. It was the “Squalo” antenna, or square halo. In fact, it’s just a square folded dipole. It radiates in all directions, with -4dB gain on the sides (compared to the front and back side).

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HEDZ antenna for 80 and 160m

Introduction

The HEDZ for 80m and 160m requires 3 poles A, B and C. Pole B is 15m tall, A and C are 9m. The distance from A to C is over 100m.

The HEDZ for 80m and 160m requires 3 poles A, B and C. Pole B is 15m tall, A and C are 9m. The distance from A to C is over 100m.

The zeppelin antenna (or simply “zepp”) is a popular end-fed wire antenna for shortwave bands and has lots of simularities with the J-pole antenna. It consists of a long wire (half wave length), connected to one of the wires of a balanced feedline (quarter wave length). The idea is that the end of the wire has a high impedance, and the quarter wave transmission line transforms this to a low impedance, at least low enough to get to 50 ohms using a balanced tuner. A Double Zepp is a normal zepp, but the other (unconnected) wire of the feeder is also connected to a second wire. The Extended Double Zepp (EDZ, sometimes also known as Double Extended Zepp or DEZ) is the same, but the wires are now 5/8 wavelength instead of 1/2. The tricky part of this antenna is now the length of the feeder. Paul N8ITF gives you the measures for all versions of the EDZ. — more →

DK7ZB yagi for 144MHz

Introduction

The result.

My DK7ZB yagi for 144MHz

After the somewhat disapointing results of the DJ9BV antenna, I decided to try another model. This time I selected a 9 element DK7ZB for my test. I already bought some square alu bars, each 250cm tall. Since the 9 element DK7ZB is 5 meters tall, this should fit perfectly.

Click here to visit DK7ZB’s homepage, including all his antenna designs and lots of references. — more →

DJ9BV yagi for 144MHz

Introduction

I just started building a new yagi antenna for 144MHz. I used to work with short yagi’s, based on DL6WU, with 6 elements. These antenna’s were about 2m long. I stacked them, tested them both vertically and vertically polarized/stacked, etc. I did lots of DX using these antenna’s. After a long period without radio activity I finally decided to start again with the hobby and try another antenna design. — more →

6-Element yagi for 144 MHz

Introduction

My homebrewn VHF yagi antenna's in Elst, stacked, about 12m above the ground.

My homebrewn VHF yagi antenna’s in Elst, stacked, about 12m above the ground.

I designed this antenna in 1995. I wanted a horizontal antenna which has nice characteristics for contest usage. The side lobs are minimized, the beam width is quite large while it has a reasonable gain and front/rear ratio. — more →

HF 1:4 balun

Introduction

hf-balun-case2Some years ago a friend offered me an HF radio: an Icom IC-730. I decided to buy it, since I didn’t have a HF rig yet. I gave it a nice place on my shelf, connected some meters of wire on the antenna plug, and from that moment I sometimes listen to all kind of chirps and beeps. I recovered my Hamcomm modem to see some wxfax images and SSTV, I tried to follow CW QSO’s again, listened to some conversations in SSB, etc.

Although this is not bad at all, I wanted to participate again. Since I moved to Utrecht, my radio activity was very low. I didn’t have any antennas on the roof, which made it difficult to pick up this nice and interesting hobby again. But… after participating in the 2002 jamboree on the air I decided to revive my radio hobby. And since I moved back to the country late 2005, I had all opportunities to set up antenna’s.

The first HF antenna I wanted to build was a Windom Antenna. This antenna required a 1:4 balun, so I made one. — more →