X10 RF Receiver Antenna

[XYTSRM]

While I understand that this site has nothing to do with X10technology per se; this question is a purely RF issue.

An X10 device, model CM15A, contains a receiver andtransmitter; my question concerns the receiver. The receiver operates in the 310Mhz band, the antenna consists of awire, approximately 4.5" [appears to 1/8th wavelength] feeding aninductor-capacitor-inductor Pi-network with a capacitor in parallel with thePi-leg at the input to a HiMark RX3310A chip [presumably a tuned ckt.].

I want to increase the reception of the CM15A; would simplyincreasing the length of the antenna wire to 9.25" [1/4 wave] besufficient; would increasing the length beyond 1/4" wave be even morebeneficial, if so what would be an optimum length (e.g. 1/2 wave, 3/4 wave,etc.)?

Any help would be greatly appreciated.

X.

[AE7RZ]

I would ask the guys here.

[XYTSRM]

I would ask the guys here.

Unfortunately there are no RF experts on the the X10 Forum; that's why I posted on this site.
As stated, my question is not an X10 technology issue, it's an RF issue; thought I'd come to the RF experts.

Thanks anyway,

X.

[KE5MC]

What I know of X10 (limited) and before I looked up the manual for the CM15A is consistent. X10 uses the house wire to send and receive the signals. It not an over the air operation. I don't think changing the"antenna" is going to help. I believe what you are seeing is the means of coupling the output and input of the X10 controller and devices. I have heard that all devices have to be on the same circuit/branch/leg of the incoming power. Maybe that information is still current and a direction to search. I am assuming that some of your devices are not receiving commands or their data is not being received?

Page 3 of the manual.

"The ActiveHome Pro Interface connects to your PC’s USB port and then
plugs into a standard AC wall outlet. The ActiveHome Pro software tells
the Interface what to do. The Interface then sends digital signals over your
existing house wiring to Modules that receive the signals and execute the
commands sent by the Interface."

While I understand that this site has nothing to do with X10technology per se; this question is a purely RF issue.

An X10 device, model CM15A, contains a receiver andtransmitter; my question concerns the receiver. The receiver operates in the 310Mhz band, the antenna consists of awire, approximately 4.5" [appears to 1/8th wavelength] feeding aninductor-capacitor-inductor Pi-network with a capacitor in parallel with thePi-leg at the input to a HiMark RX3310A chip [presumably a tuned ckt.].

I want to increase the reception of the CM15A; would simplyincreasing the length of the antenna wire to 9.25" [1/4 wave] besufficient; would increasing the length beyond 1/4" wave be even morebeneficial, if so what would be an optimum length (e.g. 1/2 wave, 3/4 wave,etc.)?

Any help would be greatly appreciated.

X.

[XYTSRM]

What I know of X10 (limited) and before I looked up the manual for the CM15A is consistent. X10 uses the house wire to send and receive the signals. It not an over the air operation. I don't think changing the"antenna" is going to help. I believe what you are seeing is the means of coupling the output and input of the X10 controller and devices. I have heard that all devices have to be on the same circuit/branch/leg of the incoming power. Maybe that information is still current and a direction to search. I am assuming that some of your devices are not receiving commands or their data is not being received?

Unfortunately you don't have a complete understanding of the CM15A. The CM15A can send both power line signals, and RF signals. If you examine a picture of a CM15A you will note the antenna attached to the side; this is the receiving antenna. Internally, within the box, there is a transmit antenna. I have already modified the CM15A with a novel transmit antenna, but I am dissatisfied with the reception. As stated in my original post the original receiving antenna appears to a 1/8 wave. I would like to simply extend the length, but I'm not sure what the optimum trade-off would be as impedance becomes a factor and a mismatch could undo any benefit from lenghtening.

[XYTSRM]

What I know of X10 (limited) and before I looked up the manual for the CM15A is consistent. X10 uses the house wire to send and receive the signals. It not an over the air operation. I don't think changing the"antenna" is going to help. I believe what you are seeing is the means of coupling the output and input of the X10 controller and devices. I have heard that all devices have to be on the same circuit/branch/leg of the incoming power. Maybe that information is still current and a direction to search. I am assuming that some of your devices are not receiving commands or their data is not being received?

Page 3 of the manual.

"The ActiveHome Pro Interface connects to your PC’s USB port and then
plugs into a standard AC wall outlet. The ActiveHome Pro software tells
the Interface what to do. The Interface then sends digital signals over your
existing house wiring to Modules that receive the signals and execute the
commands sent by the Interface."

I have been using (and modifying) X10 devices for over 25 years and I can assure you that the CM15A has the capability the RF receive and transmitt in addition to the original Powerline signals (even though the manual doesn't specifically mention the feature). If you still need further evidence examine the second page of the CM15A schematic, originally submitted to the FCC for approval. You will note the HiMark receiver chip and the circuit configuration I mentioned in my original post. You may also note that when the original submission was made the receiving antenna was specified as 240mm, (1/4 wave @ 310MHz), the actual production unit is using a 120mm (1/8 wave) antenna.

http://davehouston.net/CM15A.pdf

I am actually sorry that I even mentioned X10 as it's been nothing but a distraction from my original question. So I would ask this site to forget I am dealing with X10 devices and I will now restate the question.

************************************************** ************************************************** *******

I am looking for help from someone with experience in antenna theory. I have a generic RF receiver, comprising a HyMark receiver chip feed by an inductor-capacitor Pi matching network and an 1/8 wave vertical-wire antenna. Is there any received signal gain advantage to be achieved by lengthing the existing antenna by some multiple of 1/8 wave, and if so what multiple would be optimum?

[AE7RZ]

Unfortunately there are no RF experts on the the X10 Forum; that's why I posted on this site.
As stated, my question is not an X10 technology issue, it's an RF issue; thought I'd come to the RF experts.

Thanks anyway,


X.

X10 is all about RF. Did you ask there or did you assume no one there could help you? TUICEMAN is very knowledgeable about everything X10 related. I'll bet he can help.

[KD4MOJ]

What I know of X10 (limited) and before I looked up the manual for the CM15A is consistent. X10 uses the house wire to send and receive the signals. It not an over the air operation. I don't think changing the"antenna" is going to help.

The CM15 antenna receives the RF remote signals (like the palm remote controllers) then transmits the signal over the house wiring to the other devices address'. I use X10 in all my rooms, basically control the entire house.

As to the original question, I have put a TM751A (RF Receiver) where I had a RF range issue but that was completely on the other side of the house in the garage. Never tried to expand the original antenna.


...DOUG
KD4MOJ

[AE7RZ]

I did extend the range of my CM15A by coupling a 19" piece of wire to the existing antenna and installing the CM15A at ceiling height.

[KF7MBM]

All but 3 fixtures in my house are X10 controlled. I have a motion detector in the hall, a bunch of pad links(?) and some of those stick on switches.

I used the antenna from what was probably a 900Mhz phone base station to increase the range of my CM15A. It's connected to the original wire without cutting it and the right angle bracket is double stickty taped to the CM15A so that it looks more or less original. I also have it plugged into an extension cord so that it can sit on top of a kitchen cabinet. I can reach it from anywhere in the house but have to get it down to connect the USB.

Michael