Life Form Scanner – The search for a short antenna

Well I’m almost done with the mechanics of my dome periscope, and I’m turning my attention to the life form scanner, in particular the antenna to raise and lower it.

Just like with the periscope the limitation will be the height of the dome. I can’t extend the antenna into the body because of the slip ring cross bar on the top of the body – so anything I come up with has to remain within the 9-10 inches of the dome.

Everyone has a different approach to things. I plan on making my own radar screen and body/cap assembly. My rough sizing calculations have it coming out around 6″, maybe a little shorter, from the top of the radar screen to the bottom of the body.

From studying photos of what other people have done, most seem extend the antenna into the body, but as I said – I don’t have that luxury. But what they also do is un-attach the antenna from the spool/motor housing. This allows you to rotate the antenna 90 degrees saving some space, rather than having the motor adding to the height.

A couple of weeks ago I bought the shortest antenna I could find on eBay hoping it could get it to work, the jury is still out but I suspect I’ll need to find something even shorter.

It’s a Harada MX-1 and once I removed some housing and un-attached the mast from the body this is what I was left with

Unfortunately, the mast was still too long, collapsed it’s close to 7″, and once I stick the LFS assembly on top that’s still too tall.

This is a rough drawing on what the plan is

So I’m still looking for a short (and cheap) antenna. I did find this one (a Metra 44-PW32) which is meant for old school Minis, but the cheapest I’ve found it is $73 – which is more than I want to pay at this point.

The mast is approx. 5 1/2 inches when collapsed which should work if I extend the body of the LFS assembly over it

So if anyone has a lead on something please let me know.

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Posted by Chris on July 26th, 2008 in Dome, Electronics | No Comments

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