Please Name My Blog » homebrew

Magnetic Loop Antenna Plan for HF operation

mypapit — Mon, 02 May 2011 06:32:55 +0000

Magnetic loop is an ideal antenna for Ham radio HF operation particularly because it is relatively small and portable when compared to other forms of HF antenna.

Here are some videos demonstrating the use of Magnetic Loop antenna

W2BRI has a page on how to build Magnetic Loop for HF operation.

Hamradio Homebrew 2 Meter Square Dipole Plan

mypapit — Fri, 27 Aug 2010 17:04:07 +0000

Here is a plan for homebrewing a 2 Meter Square Dipole plan. The advantage of this antenna is that it is unidirectional, and it takes less space than the regular 2 meter dipole. The calculation included on the diagram below is for building the antenna using copper tubing, you should use MMANA-GAL or other antenna simulation software to come up with new dimension for other materials (aluminium, wire, etc).

Click on the diagram to enlarge it. Hopefully this will help you in brewing new antennas! Original plan taken from KOFF website

The Homebrew Slim Jim Antenna Gain

mypapit — Tue, 10 Jun 2008 07:43:49 +0000

I’ve been searching for information regarding the radiation angle and the gain of slim jim antenna, but found none of it. So I decided to build the model of the antenna inside the ever useful MMANA-GAL software to get the information I needed myself.

From what I can surmise, the slim jim has a slightly lower radiation angle than vertical dipole antenna and is easier to mount, thus it is suitable to use for point-to-point communication VHF-UHF operation. It has a gain of about 2.8dBi-3.2dBi in free space and 4.8-5.8dBi when mounted at about 30feet from the ground. Here’s the result of MMANA-GAL :

Slim Jim mounted 30 feet above ground

Slim Jim in free space

Moxon Antenna Plan for 27MHz CB and Freeband Operation

mypapit — Tue, 03 Jun 2008 12:16:57 +0000

Here’s another 11 meter Moxon Antenna plan suitable for 27MHz CB, Freeband and lower 28MHz Amateur Radio operation band.

Dimensions
A- 392.09 cm (154 3/8 inch)
B- 58.62 cm (23 1/16 inch)
C- 11.25 cm (4 7/16 inch)
D- 73.4 cm (28 7/8 inch)
E- 143.27 cm (56 7/16)

Gain, Radiation Pattern (mounted at approx 30feet)

Gain : Approx 10-11dBi (30 feet above the ground)
Freq range : 27.300 MHz – 28.300 MHz

The main advantage of Moxon rectangle antenna are :

Compact and Small
Has considerable gain
It can eliminate noise on HF band
Easy to construct
Suitable for HF operation (mid-low radiation angle)

Refer here for 10 meter Moxon Antenna Plan for Amateur Radio operation (28.2MHz-28.8MHz) : 10 Meter Band Compact directional antenna, Moxon

2 meter 5/8 ASTRA Antenna Plan – KakiBiawak

mypapit — Fri, 16 May 2008 05:00:38 +0000

I think many of you might have heard about this particular 2 meter VHF antenna. Called
“Antenna ASTRA” which derived from the name of one of the most popular Amateur Radio Society in Malaysia.

Here is the details of its construction. Click on the photograph to enlarge it.

KakiBiawak @ Astra Antenna in action

Homebrew a creative Morse Key for CW Operation

mypapit — Fri, 09 May 2008 16:22:49 +0000

Watch this video for ideas to homebrew Morse Keyer for CW operation.

Homebrewing 6 Element OWA VHF Yagi (10dBi) – hamradio

mypapit — Thu, 01 May 2008 10:25:59 +0000

Here are few photos that 9W2AZV and I have taken during the course of building our 6 element OWA yagi with 10dbi gain.

Materials used to contruct the antenna

8mm aluminium tube, 20 feet
6 feet length of 3/4″ PVC plumbing pipe
Ordinary household plug box

We use a plan taken from LB Cebik (W4RNL) website, first covered in : 10dBi – 6 element OWA Yagi-Uda Antenna for 2 meter band

Here are the photos of the antenna in construction :

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Tools used

The total cost of the yagi construction was RM25 (USD 8.50) for the materials alone. Later we put it on a cheap tv antenna rotator which cost us another RM40 (USD 13.5)

Here are the video of the antenna mounted on ordinary TV rotator :

Antenna Performance
The antenna has 1.3:1 reading (20watt) tx on 145.575MHz. 1.1:1 on 145.0MHz and 1.75:1 on 148.0MHz.

Up until now the antenna have recorded a distance record of approximately 180km on 2 meter FM QSO (from Beseri, Perlis to Bukit Merah, Perak) on 5W (51, 53 signal report). Other record includes distance communication between Alor Setar and Parit Buntar (distance 110km) on 10W (signal report 53,53).

The theoritical distance of this antenna if is mounted sufficiently high enough above obstacle is about 400km-500km. We only manage to mount it about 20 feet above the ground

You can find the antenna plan on : 10dBi – 6 element OWA Yagi-Uda Antenna for 2 meter band

Homebrew 5/8 Mobile Antenna Plan

mypapit — Wed, 30 Apr 2008 10:51:27 +0000

I never built 5/8 antenna, commonly used by mobile station. However, I found a good plan which you may use to homebrew a mobile antenna yourself. The plan is usable for constructing antenna for HT too :

Full article – : Homebrew 5/8 Mobile Antenna

Youtube: Morse Code Practice Oscillator in Action

mypapit — Fri, 18 Apr 2008 17:43:30 +0000

For starters… It does not actually sounds like that, I had to lower the voltage because the speaker output is too loud and you can hear that i’m not a good at sending morse too.

Still in progress, I’m still looking to modify it abit and put it in a nice box and attach it with a decent key.

At last my Morse Practice Circuit Completed – sort of

mypapit — Fri, 18 Apr 2008 09:59:18 +0000

As promised in the previous post,Simple Morse Practice Oscillator Circuit has been completed. Sorry, I cant do anything much with the photo quality as it was taken using my stupid mobile phone.

I promise to include a Youtube video demonstrating its sound and operation. Next, I need to get a decent casing and some cheap morse keyer to go with this oscillator. I might be planning to make one that could interface with CWirc too.