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Medic33

GP Patch & Questions

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Hi;

Been lurking here for a bit... finally got around to putting together the GP Patch antenna this weekend. Had a problem getting PCB mount SMA connectors, but was able to modifty things so that I could use the crimp style connector that I did get. Only done static tests so far, will have to play around with it to see if it improves my range and quality. If not, I blame my workmanship, not the design!!

2 questions: What is the approximate beam angle for the antenna? Just so that I have an idea where I need to keep the helicopter in relation to the patch.

2nd - considering a new Wireless A/V system. What are the advantages / disadvantages of 5.8 vs 2.4 GHz? Is it only related to a less cluttered band plan, or are there others? I'm flying a Trex 600 electric, and I know the electrical environment of a large R/C Helicopter is NOT kind to quality and range.

Thanks for having this forum and the site, it has been very educational!

ed.

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What is the approximate beam angle for the antenna? Just so that I have an idea where I need to keep the helicopter in relation to the patch.

I recall it is roughly 60 degrees (-3dB beamwidth). But at close piloting distances such as used with model heli's, I think you will find the antenna will provide adequate signals much further than that. For example, I've flown behind it and have still received the video image at close distances. Long story short, just use it to find what works best in your environment.

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Thank you for your input. I discovered why my signal wasn't very good.... The current camera & transmitter I'm using is a Goscam unit with a whopping 2mW of output power! That's right, a WHOLE 2mW!!! Wow. Power really does corrupt.

Needless to say, I'm looking at the DCAV site for new kit. How many people are actually using the 450mW 2.4 transmitter? Any concerns with it affecting Spektrum RC systems ( I use 72Mhz, just would prefer not to drop everyone elses helicopter from the sky. I'm soo nice.) or 802.11 wireless systems?

I would like to stick with my current (Goscam) reciever as it is a USB direct injection box. The specs look identical to the output of the Airwave system.

Goscam specs:

http://www.goscam.com/en/en_product_view.php?Id=86

Any thoughts?

Thanks for all the help so far!!

ed

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That's right, a WHOLE 2mW!!

Actually, that is too generous. :) The FCC Part 15 spec for the allowed field strength is 50mv/meter at 3 meters. So, with a standard dipole antenna like they provide, the maximum RF power into the dipole would need to be less than 0.5mW to ensure license-free compliance.

I would like to stick with my current (Goscam) reciever as it is a USB direct injection box. The specs look identical to the output of the Airwave system.

The video levels, emphasis curves, audio sub carriers, and so on will vary with each brand or model. My advice is to purchase matching Tx/Rx sets (avoid mixing brands and/or models).

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