Short version: Is the same antenna type used for transmitting as is used for receiving if the frequency is the same?
Long version: My garage door opener uses 433 MHz to receive signals from the remote control. The antenna it a wire, about 30 cm (one foot) long. The door opener transmits its status to a control device we have in the house. When transmitting it uses 868 Mhz. The antenna for transmitting is a wire about 8 cm (3 in) long. The control device we have in the house contains two antennas, both wires about 8 cm long. One I assume for receiving and one for transmitting.
I assume I can replace the 30 cm wire in the door opener with a 433 MHz antenna like this (http://www.ebay.co.uk/itm/New-SMA-Male-Crimp-RG174-GSM-GPRS-433MHz-Antenna-Sucker-Cable-3dbi-Magnetic-Base-/161525785843?hash=item259bafe4f3:g:fcoAAOSwuMFUkqWO) and the receiver antenna in the indoor control device (which I'm anyway going to put in a custom case) with this (http://www.ebay.co.uk/itm/868MHZ-915MHZ-GSM-3G-Sucker-Omnidirectional-High-gain-Antenna-7DBI-super-/201249960496?hash=item2edb6eb230:g:J3IAAOSwuMFUj-2c).
But what about the transmitter antennas? Are there custom transmitter antennas or can I buy a 433 MHz antenna and use that for transmitting at 433 MHz?