Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

extend range on a RF remote transmitter for automatic gate

Status
Not open for further replies.

privas

Junior Member level 3
Joined
Jan 28, 2006
Messages
25
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,674
rf automatic gates

My remote control has a range of about 20-50ft and I need to extend it to least 300ft. General Specifications of remote transmitter

Dimensions: 1.6 in L x 0.8 in W x 4.2 in H (41 x 20 x 107 mm)
Power: Two 3V 2032 type lithium batteries (supplied)
Battery Life: Up to five years
Frequency: 318 MHz
Number of Codes: 1,000,000 plus
Block Coding: Units are sequentially coded at the factory to customers specifications. Facility code may be specified.
Channels: one channel

I have two ideas.

1) increase the watts it puts out. Right now it has 1/8 watt transmitter. I think increasing to 1 watt or more would probably work

2) solder an antenna and amplifiy the signal.

Anyone have ideas or suggestions?
 

throwaway18

Advanced Member level 2
Joined
Jun 9, 2005
Messages
596
Helped
101
Reputation
202
Reaction score
24
Trophy points
1,298
Location
Kent, UK
Activity points
8,362
how to extend range of a gate remote

There are lots of things you need to consider.

This transmitter will produce a power output of around
1-100uW

The gain of that loop antenna is probably in the region of -10dBi plus your hand and body will affect the signal.

300feet with no obstables is easy, you just need the receiver high enough above the ground. If you have several concrete and steel buildings in between the transmitter and receiver then you can have difficulty communicating with 1watt.

Consider your receiver. If it is inside a house then the signal has to pass through a wall to get to the receiver which will reduce the range lots.

The receiver will much work better if it is on top of a 3m pole on top of the house then if it is inside a garage.

Multipath reception can be a problem. The signal can travel directly from the tx to the. It can also bound off the ground and buildings and arrive via a longer path. IF the direct signal and the reflected signal arrive with oppose phase and similar strength they cancel out.
Sometimes multiple antenas are used with a circuit that selects the antenna with the strongest signal. Sometimes several receivers are used.

If you want to extend the range in one direction, such as along the road to your house you could use a receiver antenna with gain.
Perhaps an HB9CV antenna on the roof of the house pointing a few degress below horizontal.

IF you use the transmitter from a car you would wire it to a UHF magnetic mount antenna stuck on the roof of the car.
http://www.ssejim.co.uk/mobileants.htm

If you can't find one for 318MHz then a cheap mag mount antenna for 144MHz amateur radio or VHF taxi use will doo if you cut a bit off the whip to make it λ/4 long at 318MHz.

You could try adding a telescopic antenna to the transmitter.

Personally I'd use somthing different instead of building an amplifier.
Consider buying a pair of 0.5watt walkie talkies that can send DTMF tones. Connect a DTMF decoder to one of the walkie talkies
and uses it to open the gate when your enter the correct code.
 

    privas

    points: 2
    Helpful Answer Positive Rating

privas

Junior Member level 3
Joined
Jan 28, 2006
Messages
25
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,674
extend rf remote

I have to keep the same transmitter because there are several transmitter programmed into the gate system. If I changed my transmitter, I'd have to change everyones transmitter too.

I installed a high gain, directional antenna to the receiver which helped but it wasn't enough. The range that I get still varies from 20- 150ft. I need a transmitter that will always open at 300 feet or more.

Here is a link to the transmitter that I'm using http://www.linearcorp.com/product.asp?product=DNT00052A

1) What should be the length of the antenna?
2) Can I add an amplifier inbetween the transmitter and the antenna. How about an FM booster
3) Would increasing the watts on the transmitter be too diffcult?
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top