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.

Vswr in log periodic dipoole array antenna

Status
Not open for further replies.

enamshah

Newbie level 6
Joined
May 19, 2011
Messages
14
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
1,386
i am developing lpda of 1-3 ghz and i am using tau=0.942 for gain=10 dbi but when i simulate it in hfss i get a very high vswr....also the gain is low in 1-1.5 ghz(about 3-4db) and from 2.75-3ghz(about 7-8 db)......how can i reduce vswr and increase gain.......furthermore i am using n-type female connector ....does location of connector also have an affect on vswr........
 

davenn

Advanced Member level 3
Joined
Jul 1, 2009
Messages
844
Helped
192
Reputation
384
Reaction score
163
Trophy points
1,323
Location
Sydney, Australia
Activity points
6,381
as a rule of thumb with a log periodic antenna you will have 3 elements resonant on any given freq within the bandwidth range of the antenna

the books generally agree that 3 elements = ~ 6dBd gain. I would imagine it would be difficult to get much more than that without severely sacrificing other parameters of the antenna.

here's an example of a 2 - 11GHz log-periodic antenna I make use of.

attachment.php



cheers
Dave
 

enamshah

Newbie level 6
Joined
May 19, 2011
Messages
14
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
1,386
thnxs dave
but the prob of vswr still persists and i am not making planar lpda rather i am using structure based lpda(2 booms)
so how can i reduce vswr .......does location of connector also have an affect on vswr.
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
48,178
Helped
14,199
Reputation
28,657
Reaction score
12,888
Trophy points
1,393
Location
Bochum, Germany
Activity points
279,134
You should check Zi versus frequency for a systematic mismatch and correct the antenna geometry if appropriate.

If you have an asymmetric feed connection, as the above shown PCB antenna, then the cable position will affect the antenna characteristic. You can use ferrite tubes to suppress the cable common mode waves.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top