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
Tags: 10 meter, amateur, amateur radio, antenna, diy, hf, hobby, homebrew, moxon, moxon antenna
2 meter 5/8 ASTRA Antenna Plan – KakiBiawak
Ham Radio, Hobbies May 16th, 2008
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
My Homebrew 2 meter VHF Antennas
Ham Radio, Photos and Travels April 7th, 2008
Here are the photos of my homebrew 2 meter VHF antennas. One is 6 element OWA yagi and another is a 2 meter Slim Jim for omnidirectional operation
The homebrew slim jim antenna was previously featured on my blog as well as its plan. The OWA Yagi 6 element antenna plan can be obtained from this post : 6 Element OWA Yagi Antenna for 2 Meter band plan
Tags: amateur, amateur radio, antenna, Ham Radio, hamradio, Hobbies, photos, slim jim, slimjim, yagi
Hi there people! I think most of this blog readers are familiar with half-wave antenna such as the 2 meter dipole I’ve built as a side project (with height about 1 meter by itself).
But do you know the height of the tallest and biggest half-wave antenna ever built in the world? is it 30 meters? 50 meters? 100 meters? Nope.. the answer is 646.38 m or 2,120.67 feet high when measured from its base on the ground.
Unlike other ordinary radio tower which is build to ensure you can put the antenna at the highest point, the Warsaw radio mast acts as a half-wave antenna itself!
It height 646.38 meter is the exact length of the frequency it was transmitting which is 225kHz, most probably using this formula
half-wavelength = 300/freq * 0.5 * velocity factor
= 300/0.225 * 0.5 * 0.97
= 646 meter.
As comparison, my homebrew half-wave antenna is only 0.996 meter in length, and is drastically dwarf by the Warsaw radio mast radiator.
Completed in 1974, the Warsaw radio mast transmit public broadcast radio station using 2 megawatts on 225kHz frequency. It was also the tallest structure in the world (recorded on Guinness Book of Records) until it finally collapse on 1991 due to maintenance crew failure.
Despite its collapse and inoperability for more than a decade. The Warsaw radio mast still remained the tallest/biggest (and the only longwave LF ) half-wave antenna ever build in the world,
Impressive isn’t it? Take a look at the antenna site in Wikimapia.
Read more about Warsaw Radio Mast in Wikipedia.
How to measure SWR using Diamond SX SWR meter
Ham Radio March 22nd, 2008
Here’s a simple tutorial on how to measure Standing Wave Radio (SWR) for your stations setup using Diamond SX series (SX-200,SX-400,SX-600) SWR meter, commonly available in Malaysia and Singapore.
This guide assume that you are measuring SWR for a VHF antenna operating on 2 meter amateur radio band (144 MHz – 148 MHz), voice FM.
Step 1
Firstly ensure that you’ve connected your rig and antenna to SWR meter securely. Ensure that the “blue button” is not depressed.
Step 2
Find a frequency that is not in use. Ask first to ensure that nobody is using that frequency, never ever perform SWR testing on Repeater input or output frequency.
In northern part of Malaysia, 145.575MHz has been set aside as a testing frequency.
Step 3
Ensure that you set the SWR meter switch setting to CAL as in the photograph.
Make sure your rig is set to transmit on the lowest power level setting acceptable by the SWR meter (usually around 5watt), any interference should be minimized.
Press PTT button and id your station, example “9W2QRT testing…”, make sure you use your own callsign!
without releasing PTT, adjust the CAL knob on the SWR meter until the needle points to red arrow to “CAL”, refer to photographs below.
Step 4
Finally, without releasing PTT, turn the switch on the SWR meter to “SWR”, as shown in photograph :
The meter will display SWR for your antenna setup. In this case 1.5:1. Dont forget to release PTT button after the test. To ensure your antenna is useful accross the band, you can repeat the test on amateur band edge, that is on 144.000 MHz and 148.000MHz.
Final thought
Remember, all test should be brief, and accompanied by your callsign, never ever transmit on repeater inputs or on busy channel.
That’s all folks.
p/s: Please leave comments if you have any information or wish to correct mistakes in this tutorial.
The Bahasa Melayu version of this guide is available on Forum Ham Radio Anak Perlis
Tags: amateur radio, antenna, geek, guide, hamradio, howto, radio, rig, swr, tutorial
Not to be rude, but I don’t response to “Contact Contact…”
Ham Radio March 1st, 2008
I write this because I want to clarify the reason why I do not prefer to answer to station which uses “Contact contact” to join in radio conversation (QSO) or to call for attention.
The correct standard operating procedure (SOP) dictate that every transmission should be accompanied by a valid callsign, so it could be distinguished from an unauthorized station (pirates). Furthermore, it will make things difficult for the would-be responding station to know the intention of the calling station if the latter uses “Contact Contact” lingo.
If the radio station is calling for attention it should start with “9w2qrt calling for any station, and standing by” or on a simplex channel, “cq cq cq, this is 9w2qrt calling for any station and standing by”.
Or if the station want to join an on-going conversation (QSO), he/she should say “9w2qrt, join” or any variation of it which involves using a valid callsign.
Using a valid callsign instead of “Contact, Contact” has its own advantage since it is widely recognized internationally. Besides that, it could shorten the QSO joining process since one has already stated his/her callsign and intention on the frequency.
If you are a certified amateur radio operator, then you have nothing to hide, just transmit your callsign and be proud. “Contact, Contact” is a lingo used by indonesian pirates who are known to cause interference and other disturbance across the band, there’s nothing special about this except that it lengthen the voice procedure.
Just remember, transmitting without identifying your station is illegal. Even if does not care about the legality, do show care about your reputation and professionalism when on air. It reflect how well people perceives you as an able operator.
Why “Contact Contact” is bad?
Another explanation can be found here – Ebook Panduan QSO
Amateur Radio Callsign here is 9W2WTF
Announcement, Ham Radio, Hobbies February 26th, 2008
For those who are wondering, I am a licensed Amateur Radio operator and my callsign is 9W2WTF. I live in the northern part in Malaysia, in a town called Alor Setar.
As an amateur radio operator I usually monitor local repeater (145.525 MHz -0.600, tone: 103.5) and local simplex on 145.425 MHz mostly during night time.
I use an Icom v8 and Icom IC V8000 as my communication equipment. My hobby includes antenna homebrewing and finding the most energy efficient way to transmit as far as possible using the least power.
That’s all for now. Thanks for visiting. I can be reached at [email protected], or [email protected]
73 to all 
Tags: 9w2wtf, amateur radio, antenna, hamradio, Hobbies
Amateur Radio Coax Cable Power Loss calculator (RG 58, RG-8)
Ham Radio, Random Facts February 21st, 2008
Ever wonder how much power is loss in your coax cable feedline? Here is a website which helps you estimate power loss in your antenna feedline according to your choice of coax cable.
For example :
If you are transmitting on 145 MHz frequency with 65 Watt of power using 15 meter RG-58 cable, the maximum effective power radiated by your antenna is just about half of the transmitting power (36.156 MHz).
But when you switch to RG-8 cable, the loss would be significantly lower, and your antenna would radiate 54 Watt of power.
Since the power loss is significant, it is advisable that you consider the choice of your feedline before setting up your station. In emergency or QRP situation, every 1 Watt counts.
If you have no other choice other than to use RG-58 cable, it is advisable to put your antenna as high as possible with the shortest amount of cable possible. This will save your rig a lot of hard work, and may actually get your signal to travel further than before
How much power loss in your feedline ? Check it at Coax Cable and Line Loss Calculator website
Tags: amateur radio, antenna, facts, hamradio, Hobbies
Howto – 2 Meter Slim Jim antenna from Ordinary Wires
Ham Radio, Hobbies February 17th, 2008
Slim Jim (J Integrated Match J-Pole) is probably the most easiest and powerful 2 meter antenna to build provided you have the exact measurement and material to build it.
This how to will show you how to build a 2 meter slim jim antenna from ordinary insulated copper wire commonly used for carrying AC (alternate current) electricity in your household.
Slim Jim construction basic
I am not only going show you the measurement of slim jim antenna for specific frequency, but I’m going to show you how to calculate slim jim antenna by your own using the basic formula below.
The figure above shows that the longest side of slim jim is 3/4 wavelength long and the shorter side of the slim jim consist of 1/2 wavelength and 1/4 wavelength long seperated by a gap.
The feedline (coax cable) is normally connected 1/20 wavelength from the bottom of the slim jim antenna with the center conductor connected to the longest side and the shield/braid is connected to the shorter side.
Building the Slim Jim antenna
This guide assume you want to build a slim jim antenna that centered on 146MHz.
Calculation
The formula for calculating wavelength in metric system is 300/(freq MHz)
Using the formula from the figure, we have :
300/146 = 2.055 M
Wavelength = 205.5 cm
Wavelength x copper wire velocity factor = 205.5 cm x 0.94
= 193.17 cm
3/4 wavelength = 193.17 x 0.75
= 144.88 cm (57″)
1/2 wavelength = 193.17 x 0.5
= 96.585 cm (38″)
1/4 wavelength minus gap = 193.17 x 0.25 – 2.6 cm
= 45.69 cm (18″)
Coax tap = 193.17 x 1/20
= 9.6 cm (3 3/4″)
Building Materials
- 3/4″ diameter PVC (20mm) – 6 feet (180 cm)
- ordinary insulated copper wire for carrying altenate current (AC) – 11 feet (3.40 meter)
- Cable ties
Tools
- Soldering iron
- Glue gun
- Somthing to make a hole on PVC pipe
Wire Slim Jim Building Steps
- First take the PVC pile and measure it according to the 3/4 wavelength formula above (144.88 cm).
- Make two holes at the opposite side of the pipe. This hole is used for putting the copper wire through the pipe. Repeat this step 144.88 cm away from the top hole. Both of these holes will hold the copper wire.
- Insert the wire through the hole until both end reaches each other on one side of the PVC pipe. Then measure the length of the wire and cut the wire on that side so the setup resembles the figure above.
- Cut the wire insulation (but leave the wire uncut) 1/20 wavelength away (9.6 cm) from the bottom of the PVC pipe, again refer the figure above.
- Solder the center of the coax cable at the longest side of the slim jim (3/4 wavelength part) and the braid/shield at the shorted part of the antenna.
- Test the antenna using SWR meter to ensure that its SWR is at minimum or within acceptable level.
- There you go, you’ve build yourself your own 2 meter Omnidirectional Slim Jim antenna for less than USD2 (RM 6.00)
2 Meter Wire Slim Jim Antenna in action
Tags: antenna, diy, Hobbies, hobby, homebrew, slim jim, slimjim
Homebrew 2 meter Amateur Radio Antenna from Ordinary TV Rabbit Ears antenna
Ham Radio February 12th, 2008
Short on a good and reliable antenna for your amateur radio operation ?
Here’s how to make a simple 2 meter amateur radio antenna from ordinary tv antenna (Rabbit Ears Antenna).
For your information these antenna can be bought from local tv store at around RM4 a piece (less than USD2).
The best thing about these antenna that it has terminating point (screw) which you can screw in your coax cable to each dipole leg, as shown in the (rather blurry) photo.
After that, extend the telescoping element to the desired length to match your transmitting frequency.
Usually amateur radio operator working on 2 meter VHF would use antenna with vertical polarisation. In this case, you need to spread the dipole to vertical position like pictured above, connect it to your transceiver and be amaze by its transmitting (or receiving) power.
Main Advantage of This Antenna
- Embarassingly easy to construct
- Lightweight
- Can be adjusted to any frequency, because of its adjustable telescopic element
As you can see, the rabbit ear tv antenna can also make a good antenna during emergency situation. Its adjustable telescopic elements made it easy to reconfigure the antenna to transmit on different frequencies.
ps : You can use this dipole calculator, if you unsure about the dipole length.
Tags: amateur radio, antenna, dipole, diy, hamradio, homebrew
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