# duplexer Frequency dependent. Three port device, enables use of common antenna for concurrent transmission and reception on different frequencies, with isolation between them. Isolation obtained by 2 [band pass filter](band%20pass%20filter.md)s in the transmitting and receiving path. ![Pasted image 20220829083717](attachments/Pasted%20image%2020220829083717.png#invert) ## Robabeh Explanation ![Pasted image 20220829091831](attachments/Pasted%20image%2020220829091831.png#invert) Commonly use same antenna -can also have separate antenna Transmit/receive while sharing antenna Is the gain of each of those [low noise amplifier](low%20noise%20amplifier.md) - used on receiver because it a small signall easily impacted by noise. ![Pasted image 20220829091854](attachments/Pasted%20image%2020220829091854.png#invert) Bandwidth is not too wide (transmit and receive [channels](channels.md)) Channelise the band - we don't worry about this. 2 Bandpass filters - called a duplexer. Tranmist BPF - high rejection in the receiver band. Tx [leakage](leakage.md) can make its way through the duplexer. Need extremely good BPF's. Desensitise the LNA - big signal coming in ![Pasted image 20220829092450](attachments/Pasted%20image%2020220829092450.png#invert) [Dynamic Range (DR)](Dynamic%20Range%20(DR).md) - it will desensitise the LNA Also other phones transmitting too - blocking signal from nearby transmitters. --- # References [](../../Calendar/daily/2022-08-29.md#Robabeh%20Meeting)