ferdem
Full Member level 2
- Joined
- Oct 18, 2008
- Messages
- 135
- Helped
- 31
- Reputation
- 62
- Reaction score
- 35
- Trophy points
- 1,308
- Location
- Türkiye
- Activity points
- 2,866
Hi friends! I would like to hear your advices to keep the insertion loss minimum in coaxial-aluminium box-board transition, frequency band is X-band.
I have used various connectors, mounting methods in lower bands and had no problem but I'm new for X-band. I know that aforementioned transition becomes critical and requires care above 6 GHz.
First I will try using four hole flange mount connector shown below:
https://www.digikey.com/product-detail/en/HRM(V)-306S/H11564-ND/1786506
Some connectors' dielectric material extends into the box along with the inner conductor, the diamater of the material(PTFE er:2.1) is set 4.1mm providing 50ohm impedance for a coaxial line. I guess it helps impedance continuity up to board entrance. Otherwise, a short portion of the transmission line must be air filled which may hurt the impedance more or less.
Question 1: Is there any other intent/concern for extension of the dielectric material? Why/when do we prefer the conductor whose dielectric is extended?
By the way, this post answers partly, additional comments will be welcome.
Many of flange type connectors have no direct contact with board ground, they contact via box surface. I think the most problematic part is that and requires special care. For example, how is the transition affected by the surface conductivity of the box? What happens if the box is not chromate coated?
Below connector has direct connection(soldered) for both inner and outer conductor. (It is belong to a DC-18GHz unit). It looks peculiar, can you recognize it?
Question 2: Can we say that direct connection for both connectors(inner, outer) performs better compared to box contact connectors?
Question 3: Do you have flange type connectors you have already used in X-band to suggest me? Your comments about mounting considerations will also be welcome.
Thank you.
I have used various connectors, mounting methods in lower bands and had no problem but I'm new for X-band. I know that aforementioned transition becomes critical and requires care above 6 GHz.
First I will try using four hole flange mount connector shown below:
https://www.digikey.com/product-detail/en/HRM(V)-306S/H11564-ND/1786506
Some connectors' dielectric material extends into the box along with the inner conductor, the diamater of the material(PTFE er:2.1) is set 4.1mm providing 50ohm impedance for a coaxial line. I guess it helps impedance continuity up to board entrance. Otherwise, a short portion of the transmission line must be air filled which may hurt the impedance more or less.
Question 1: Is there any other intent/concern for extension of the dielectric material? Why/when do we prefer the conductor whose dielectric is extended?
By the way, this post answers partly, additional comments will be welcome.
Many of flange type connectors have no direct contact with board ground, they contact via box surface. I think the most problematic part is that and requires special care. For example, how is the transition affected by the surface conductivity of the box? What happens if the box is not chromate coated?
Below connector has direct connection(soldered) for both inner and outer conductor. (It is belong to a DC-18GHz unit). It looks peculiar, can you recognize it?
Question 2: Can we say that direct connection for both connectors(inner, outer) performs better compared to box contact connectors?
Question 3: Do you have flange type connectors you have already used in X-band to suggest me? Your comments about mounting considerations will also be welcome.
Thank you.