First attempt with homemade antennas and newly bought comercial antennas

One of the tested homemade antennas.

I have now some rudimentary test of my homemade antennas. To be honest, it isn't brilliant. I made some a roockie mistake. Error 1: I didn't measure it with an SWR meter before I deployed it in the field. As I evaluate their performance (both homemade antennas) they performed well in the beginning. But at some point the signal got weaker, and weaker, and weaker. And it seems that the one who spoke the most got weaker than the other faster. My best guess is that the tuning of the antenna is a bit off and too much of the transmitting power is transferred back to the transmitter and the overheating is strangling the transmitter. I hope no damage is done. Luckily it was a cheap chineese Puxing radio, so it isn't impossible to replace for me.

So to counter this and perhaps fix the antennas, I've bought SWR meter by Nissei (RS-40). It has recieved a bit of mixed reviews. Hopefully mine works fine. The SWR meter are going to be connected in between the antenna and the radio, measuring how much power is being transmitted and the SWR meter shows the relation between transmit power to the antenna and how much is echoed back at the transmitter. The trick here is that an antenna has different SWR at different frequencies. So my 445 MHz Duck from Smiley Antenna is pretty good at 445 MHz, however it is probably pretty misrable at 144 MHz with a high SWR value.

I have now orderen N type to BNC connectors so I actually can hook up the WSR meter and test the antennas.

In the mean time I've bought a few comercial antennas. One is a Comet antenna: 

It's small, thin, stealthy, very lightweight and VERY durable. I sure hope it is useable. It is tunes at 430 MHz, which is 14 and  16 MHz off target. But I've bought two of them so I can try to tune one to the correct lenght with the SWR meter when I get the connectors.

As you can see the Comet antenna is so flexible it can be bend from top to bottom without damaging the antenna. I think it's pretty airsoft grade.

A also bought a dipole antenna to wear on the body. I really have to experiment with this one. I have to figure out if it works on the 444/446 MHz, if I can tune it (bought two of them as well) and how to wear it on the body for best coverage.

 Another antenna, which is a pretty cool one, is a flat and Slim Jim antenna. It can be packed as roll and deployed into a tree. It is tuned at 70 cm and 2 m band (440/135). This is an quickly deploy extra antenna to improve the coverage of you radio. It has a little plastic clips on the end to tie paracord and drag the antenna into a tree. It's got 2,5 meter cord so it can get pretty high. Also it features ferrit core to eliminate RF travelling down the line and making noise. I think I should be careful with transmitting too much with this one until I've SWR tested it at 444/446.

I'll probably report back with some results in 14 days (Chineese shipping time).

Sunday morning research in Tactical Antennas

I'd like to share some of the antennas and solutions I came across with a litle sunday morning research into extisting solutions to wearable antennas.

BEA Systems announced they were working on anteanna system intergated into the fabric of the soldiers clothings - didn't find anything besides the FOG HORN and Geeky Gadgets on this. Being able to integrate it into materials would anteresting concept, however it introduces some serious compromises. Didn't find anything more detailed than this.

An American company called Pharad has an wearable antenna concept which is interessting. They say it is almost omnidirectional, which really teases my interest in the design. You should check it out Pharad product page for wearable antennas.

Making a "flat antenna" and wear it in a flat MOLLE pouch on the tactical vest is an idea share, though getting the design to de omnidirectional is an issue I havn't figured out. I imagine out would be a "Patch" antenna (please see Antenna-theory.com on Patch antennas) which is very directional antennas.

I think it resembles the Limited Visibility Concealable Antenna (LVCA) by Blackhearth International.

I also find it to resemble the TVAS (Tactical Vest Antenna System: Wiki) and the creator Wearable Antenna Techonologies

One thing all of these have in common: It is not cosumer products! In other words, we won't as airsofters get access to these antennas. That is why we have to do this our selves (DIY!). Thankfully Antenna-theory.com have started this process already, meaning that he or she, has started to write about some of the theory involved in creating such an antenna. See antenna-theory.com on wearable antennas. I think this i going to be my future project. Getting an antenna inside my Flyye 6094A vest!

Tactical antenna prototype number 3: 445 MHz whip body antenna

One of my projects is to overcome some of the horrific (radio wise) terrain we have a our sites where we play. Well, not only at our sites but the whole country. We unfortunately don't have the opportunity to select our frequency ourselves and carry around HF equipment. We are limited to 444 and 446 MHz which propagates a line of sight, which mean it doesn't help much to throw a bigger punch of power. Besides we are limited to 0.5 W RMS transmit power.

So what can we do?

One things, is that we can make antennas with high sensitivity and try to relocate them higher on our body as well as relocating to higher ground.

A future project to test might be a duplex or simplex reciever located on the high ground, but more on that another time.

My first project is a tactical antenna for the back of the tactical vest. Here is prototype three.

Basically, this is a whip antenna with a 3 winding coil just before connection. It is a half wave antenna of the 444 and 446 MHz (meaning it is tuned for 445 MHz). Contruction is pretty simple. 1 piece of rugged single core RG-58 Coax, tape, glue, a BNC connector and BNC to SMA extension cord.

I don't think the antenna is bad, it is probably just as good as the original whip antenna on my teams radios. However I do not have the numbers to show at the moment. I did a field test where it had slight better audible reception than the original antenna. The original antenna is a whip designed for both VHF and UHF. I think i have to get a SWR meter to get some actual numbers, it might improve the design as well.

I'll get back to you on the design thoughts later.

The contruction is very simple. Slice open the RG58 coax and remove mesh coating and foil. Give it a layer of electrical tape instead of the mesh and foil. Remove a part of the the coating all the way to the core, this is vere you'd like to make a coil on the antenna. I gave the antenna 3 windings, it should probably have 5 instead (have not read theory on this yet though). After I made the coil with a needle-nose plier I re-applied the outer rubber coating of the RG58 and gave it a good spin with the electrical tape. And the final step is to apply the BNC connector.

I think I'll find out how to measure the performance of this a proper way.

What is this all about?

This blog is about two of my hobbies: Airsoft and Radio communication. Airsoft is a military simulation game. It is somewhere inbetween role playing and action gaming (laser tag, paintball etc.) It's all about doing military tactics with your friends against other friends and have small 6 mm plastic bullets as a measurement of success.
That is the tactical part of this blog.
Radio communication are an important part og success in airsoft tactics. In large games, it is outmost essential to have good communication. That is why I've recently taken up the hobby of Radio Amateur and building antennas.
So this blog is on the topic of tactical appliance of radio communication and "do it yourself" projects related.